summaryrefslogtreecommitdiff
path: root/sql/sql_join_cache.cc
blob: b0fdb7a1c42ebabb8387cc7336ee0db33bc0882d (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674
1675
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
1713
1714
1715
1716
1717
1718
1719
1720
1721
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735
1736
1737
1738
1739
1740
1741
1742
1743
1744
1745
1746
1747
1748
1749
1750
1751
1752
1753
1754
1755
1756
1757
1758
1759
1760
1761
1762
1763
1764
1765
1766
1767
1768
1769
1770
1771
1772
1773
1774
1775
1776
1777
1778
1779
1780
1781
1782
1783
1784
1785
1786
1787
1788
1789
1790
1791
1792
1793
1794
1795
1796
1797
1798
1799
1800
1801
1802
1803
1804
1805
1806
1807
1808
1809
1810
1811
1812
1813
1814
1815
1816
1817
1818
1819
1820
1821
1822
1823
1824
1825
1826
1827
1828
1829
1830
1831
1832
1833
1834
1835
1836
1837
1838
1839
1840
1841
1842
1843
1844
1845
1846
1847
1848
1849
1850
1851
1852
1853
1854
1855
1856
1857
1858
1859
1860
1861
1862
1863
1864
1865
1866
1867
1868
1869
1870
1871
1872
1873
1874
1875
1876
1877
1878
1879
1880
1881
1882
1883
1884
1885
1886
1887
1888
1889
1890
1891
1892
1893
1894
1895
1896
1897
1898
1899
1900
1901
1902
1903
1904
1905
1906
1907
1908
1909
1910
1911
1912
1913
1914
1915
1916
1917
1918
1919
1920
1921
1922
1923
1924
1925
1926
1927
1928
1929
1930
1931
1932
1933
1934
1935
1936
1937
1938
1939
1940
1941
1942
1943
1944
1945
1946
1947
1948
1949
1950
1951
1952
1953
1954
1955
1956
1957
1958
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
2039
2040
2041
2042
2043
2044
2045
2046
2047
2048
2049
2050
2051
2052
2053
2054
2055
2056
2057
2058
2059
2060
2061
2062
2063
2064
2065
2066
2067
2068
2069
2070
2071
2072
2073
2074
2075
2076
2077
2078
2079
2080
2081
2082
2083
2084
2085
2086
2087
2088
2089
2090
2091
2092
2093
2094
2095
2096
2097
2098
2099
2100
2101
2102
2103
2104
2105
2106
2107
2108
2109
2110
2111
2112
2113
2114
2115
2116
2117
2118
2119
2120
2121
2122
2123
2124
2125
2126
2127
2128
2129
2130
2131
2132
2133
2134
2135
2136
2137
2138
2139
2140
2141
2142
2143
2144
2145
2146
2147
2148
2149
2150
2151
2152
2153
2154
2155
2156
2157
2158
2159
2160
2161
2162
2163
2164
2165
2166
2167
2168
2169
2170
2171
2172
2173
2174
2175
2176
2177
2178
2179
2180
2181
2182
2183
2184
2185
2186
2187
2188
2189
2190
2191
2192
2193
2194
2195
2196
2197
2198
2199
2200
2201
2202
2203
2204
2205
2206
2207
2208
2209
2210
2211
2212
2213
2214
2215
2216
2217
2218
2219
2220
2221
2222
2223
2224
2225
2226
2227
2228
2229
2230
2231
2232
2233
2234
2235
2236
2237
2238
2239
2240
2241
2242
2243
2244
2245
2246
2247
2248
2249
2250
2251
2252
2253
2254
2255
2256
2257
2258
2259
2260
2261
2262
2263
2264
2265
2266
2267
2268
2269
2270
2271
2272
2273
2274
2275
2276
2277
2278
2279
2280
2281
2282
2283
2284
2285
2286
2287
2288
2289
2290
2291
2292
2293
2294
2295
2296
2297
2298
2299
2300
2301
2302
2303
2304
2305
2306
2307
2308
2309
2310
2311
2312
2313
2314
2315
2316
2317
2318
2319
2320
2321
2322
2323
2324
2325
2326
2327
2328
2329
2330
2331
2332
2333
2334
2335
2336
2337
2338
2339
2340
2341
2342
2343
2344
2345
2346
2347
2348
2349
2350
2351
2352
2353
2354
2355
2356
2357
2358
2359
2360
2361
2362
2363
2364
2365
2366
2367
2368
2369
2370
2371
2372
2373
2374
2375
2376
2377
2378
2379
2380
2381
2382
2383
2384
2385
2386
2387
2388
2389
2390
2391
2392
2393
2394
2395
2396
2397
2398
2399
2400
2401
2402
2403
2404
2405
2406
2407
2408
2409
2410
2411
2412
2413
2414
2415
2416
2417
2418
2419
2420
2421
2422
2423
2424
2425
2426
2427
2428
2429
2430
2431
2432
2433
2434
2435
2436
2437
2438
2439
2440
2441
2442
2443
2444
2445
2446
2447
2448
2449
2450
2451
2452
2453
2454
2455
2456
2457
2458
2459
2460
2461
2462
2463
2464
2465
2466
2467
2468
2469
2470
2471
2472
2473
2474
2475
2476
2477
2478
2479
2480
2481
2482
2483
2484
2485
2486
2487
2488
2489
2490
2491
2492
2493
2494
2495
2496
2497
2498
2499
2500
2501
2502
2503
2504
2505
2506
2507
2508
2509
2510
2511
2512
2513
2514
2515
2516
2517
2518
2519
2520
2521
2522
2523
2524
2525
2526
2527
2528
2529
2530
2531
2532
2533
2534
2535
2536
2537
2538
2539
2540
2541
2542
2543
2544
2545
2546
2547
2548
2549
2550
2551
2552
2553
2554
2555
2556
2557
2558
2559
2560
2561
2562
2563
2564
2565
2566
2567
2568
2569
2570
2571
2572
2573
2574
2575
2576
2577
2578
2579
2580
2581
2582
2583
2584
2585
2586
2587
2588
2589
2590
2591
2592
2593
2594
2595
2596
2597
2598
2599
2600
2601
2602
2603
2604
2605
2606
2607
2608
2609
2610
2611
2612
2613
2614
2615
2616
2617
2618
2619
2620
2621
2622
2623
2624
2625
2626
2627
2628
2629
2630
2631
2632
2633
2634
2635
2636
2637
2638
2639
2640
2641
2642
2643
2644
2645
2646
2647
2648
2649
2650
2651
2652
2653
2654
2655
2656
2657
2658
2659
2660
2661
2662
2663
2664
2665
2666
2667
2668
2669
2670
2671
2672
2673
2674
2675
2676
2677
2678
2679
2680
2681
2682
2683
2684
2685
2686
2687
2688
2689
2690
2691
2692
2693
2694
2695
2696
2697
2698
2699
2700
2701
2702
2703
2704
2705
2706
2707
2708
2709
2710
2711
2712
2713
2714
2715
2716
2717
2718
2719
2720
2721
2722
2723
2724
2725
2726
2727
2728
2729
2730
2731
2732
2733
2734
2735
2736
2737
2738
2739
2740
2741
2742
2743
2744
2745
2746
2747
2748
2749
2750
2751
2752
2753
2754
2755
2756
2757
2758
2759
2760
2761
2762
2763
2764
2765
2766
2767
2768
2769
2770
2771
2772
2773
2774
2775
2776
2777
2778
2779
2780
2781
2782
2783
2784
2785
2786
2787
2788
2789
2790
2791
2792
2793
2794
2795
2796
2797
2798
2799
2800
2801
2802
2803
2804
2805
2806
2807
2808
2809
2810
2811
2812
2813
2814
2815
2816
2817
2818
2819
2820
2821
2822
2823
2824
2825
2826
2827
2828
2829
2830
2831
2832
2833
2834
2835
2836
2837
2838
2839
2840
2841
2842
2843
2844
2845
2846
2847
2848
2849
2850
2851
2852
2853
2854
2855
2856
2857
2858
2859
2860
2861
2862
2863
2864
2865
2866
2867
2868
2869
2870
2871
2872
2873
2874
2875
2876
2877
2878
2879
2880
2881
2882
2883
2884
2885
2886
2887
2888
2889
2890
2891
2892
2893
2894
2895
2896
2897
2898
2899
2900
2901
2902
2903
2904
2905
2906
2907
2908
2909
2910
2911
2912
2913
2914
2915
2916
2917
2918
2919
2920
2921
2922
2923
2924
2925
2926
2927
2928
2929
2930
2931
2932
2933
2934
2935
2936
2937
2938
2939
2940
2941
2942
2943
2944
2945
2946
2947
2948
2949
2950
2951
2952
2953
2954
2955
2956
2957
2958
2959
2960
2961
2962
2963
2964
2965
2966
2967
2968
2969
2970
2971
2972
2973
2974
2975
2976
2977
2978
2979
2980
2981
2982
2983
2984
2985
2986
2987
2988
2989
2990
2991
2992
2993
2994
2995
2996
2997
2998
2999
3000
3001
3002
3003
3004
3005
3006
3007
3008
3009
3010
3011
3012
3013
3014
3015
3016
3017
3018
3019
3020
3021
3022
3023
3024
3025
3026
3027
3028
3029
3030
3031
3032
3033
3034
3035
3036
3037
3038
3039
3040
3041
3042
3043
3044
3045
3046
3047
3048
3049
3050
3051
3052
3053
3054
3055
3056
3057
3058
3059
3060
3061
3062
3063
3064
3065
3066
3067
3068
3069
3070
3071
3072
3073
3074
3075
3076
3077
3078
3079
3080
3081
3082
3083
3084
3085
3086
3087
3088
3089
3090
3091
3092
3093
3094
3095
3096
3097
3098
3099
3100
3101
3102
3103
3104
3105
3106
3107
3108
3109
3110
3111
3112
3113
3114
3115
3116
3117
3118
3119
3120
3121
3122
3123
3124
3125
3126
3127
3128
3129
3130
3131
3132
3133
3134
3135
3136
3137
3138
3139
3140
3141
3142
3143
3144
3145
3146
3147
3148
3149
3150
3151
3152
3153
3154
3155
3156
3157
3158
3159
3160
3161
3162
3163
3164
3165
3166
3167
3168
3169
3170
3171
3172
3173
3174
3175
3176
3177
3178
3179
3180
3181
3182
3183
3184
3185
3186
3187
3188
3189
3190
3191
3192
3193
3194
3195
3196
3197
3198
3199
3200
3201
3202
3203
3204
3205
3206
3207
3208
3209
3210
3211
3212
3213
3214
3215
3216
3217
3218
3219
3220
3221
3222
3223
3224
3225
3226
3227
3228
3229
3230
3231
3232
3233
3234
3235
3236
3237
3238
3239
3240
3241
3242
3243
3244
3245
3246
3247
3248
3249
3250
3251
3252
3253
3254
3255
3256
3257
3258
3259
3260
3261
3262
3263
3264
3265
3266
3267
3268
3269
3270
3271
3272
3273
3274
3275
3276
3277
3278
3279
3280
3281
3282
3283
3284
3285
3286
3287
3288
3289
3290
3291
3292
3293
3294
3295
3296
3297
3298
3299
3300
3301
3302
3303
3304
3305
3306
3307
3308
3309
3310
3311
3312
3313
3314
3315
3316
3317
3318
3319
3320
3321
3322
3323
3324
3325
3326
3327
3328
3329
3330
3331
3332
3333
3334
3335
3336
3337
3338
3339
3340
3341
3342
3343
3344
3345
3346
3347
3348
3349
3350
3351
3352
3353
3354
3355
3356
3357
3358
3359
3360
3361
3362
3363
3364
3365
3366
3367
3368
3369
3370
3371
3372
3373
3374
3375
3376
3377
3378
3379
3380
3381
3382
3383
3384
3385
3386
3387
3388
3389
3390
3391
3392
3393
3394
3395
3396
3397
3398
3399
3400
3401
3402
3403
3404
3405
3406
3407
3408
3409
3410
3411
3412
3413
3414
3415
3416
3417
3418
3419
3420
3421
3422
3423
3424
3425
3426
3427
3428
3429
3430
3431
3432
3433
3434
3435
3436
3437
3438
3439
3440
3441
3442
3443
3444
3445
3446
3447
3448
3449
3450
3451
3452
3453
3454
3455
3456
3457
3458
3459
3460
3461
3462
3463
3464
3465
3466
3467
3468
3469
3470
3471
3472
3473
3474
3475
3476
3477
3478
3479
3480
3481
3482
3483
3484
3485
3486
3487
3488
3489
3490
3491
3492
3493
3494
3495
3496
3497
3498
3499
3500
3501
3502
3503
3504
3505
3506
3507
3508
3509
3510
3511
3512
3513
3514
3515
3516
3517
3518
3519
3520
3521
3522
3523
3524
3525
3526
3527
3528
3529
3530
3531
3532
3533
3534
3535
3536
3537
3538
3539
3540
3541
3542
3543
3544
3545
3546
3547
3548
3549
3550
3551
3552
3553
3554
3555
3556
3557
3558
3559
3560
3561
3562
3563
3564
3565
3566
3567
3568
3569
3570
3571
3572
3573
3574
3575
3576
3577
3578
3579
3580
3581
3582
3583
3584
3585
3586
3587
3588
3589
3590
3591
3592
3593
3594
3595
3596
3597
3598
3599
3600
3601
3602
3603
3604
3605
3606
3607
3608
3609
3610
3611
3612
3613
3614
3615
3616
3617
3618
3619
3620
3621
3622
3623
3624
3625
3626
3627
3628
3629
3630
3631
3632
3633
3634
3635
3636
3637
3638
3639
3640
3641
3642
3643
3644
3645
3646
3647
3648
3649
3650
3651
3652
3653
3654
3655
3656
3657
3658
3659
3660
3661
3662
3663
3664
3665
3666
3667
3668
3669
3670
3671
3672
3673
3674
3675
3676
3677
3678
3679
3680
3681
3682
3683
3684
3685
3686
3687
3688
3689
3690
3691
3692
3693
3694
3695
3696
3697
3698
3699
3700
3701
3702
3703
3704
3705
3706
3707
3708
3709
3710
3711
3712
3713
3714
3715
3716
3717
3718
3719
3720
3721
3722
3723
3724
3725
3726
3727
3728
3729
3730
3731
3732
3733
3734
3735
3736
3737
3738
3739
3740
3741
3742
3743
3744
3745
3746
3747
3748
3749
3750
3751
3752
3753
3754
3755
3756
3757
3758
3759
3760
3761
3762
3763
3764
3765
3766
3767
3768
3769
3770
3771
3772
3773
3774
3775
3776
3777
3778
3779
3780
3781
3782
3783
3784
3785
3786
3787
3788
3789
3790
3791
3792
3793
3794
3795
3796
3797
3798
3799
3800
3801
3802
3803
3804
3805
3806
3807
3808
3809
3810
3811
3812
3813
3814
3815
3816
3817
3818
3819
3820
3821
3822
3823
3824
3825
3826
3827
3828
3829
3830
3831
3832
3833
3834
3835
3836
3837
3838
3839
3840
3841
3842
3843
3844
3845
3846
3847
3848
3849
3850
3851
3852
3853
3854
3855
3856
3857
3858
3859
3860
3861
3862
3863
3864
3865
3866
3867
3868
3869
3870
3871
3872
3873
3874
3875
3876
3877
3878
3879
3880
3881
3882
3883
3884
3885
3886
3887
3888
3889
3890
3891
3892
3893
3894
3895
3896
3897
3898
3899
3900
3901
3902
3903
3904
3905
3906
3907
3908
3909
3910
3911
3912
3913
3914
3915
3916
3917
3918
3919
3920
3921
3922
3923
3924
3925
3926
3927
3928
3929
3930
3931
3932
3933
3934
3935
3936
3937
3938
3939
3940
3941
3942
3943
3944
3945
3946
3947
3948
3949
3950
3951
3952
3953
3954
3955
3956
3957
3958
3959
3960
3961
3962
3963
3964
3965
3966
3967
3968
3969
3970
3971
3972
3973
3974
3975
3976
3977
3978
3979
3980
3981
3982
3983
3984
3985
3986
3987
3988
3989
3990
3991
3992
3993
3994
3995
3996
3997
3998
3999
4000
4001
4002
4003
4004
4005
4006
4007
4008
4009
4010
4011
4012
4013
4014
4015
4016
4017
4018
4019
4020
4021
4022
4023
4024
4025
4026
4027
4028
4029
4030
4031
4032
4033
4034
4035
4036
4037
4038
4039
4040
4041
4042
4043
4044
4045
4046
4047
4048
4049
4050
4051
4052
4053
4054
4055
4056
4057
4058
4059
4060
4061
4062
4063
4064
4065
4066
4067
4068
4069
4070
4071
4072
4073
4074
4075
4076
4077
4078
4079
4080
4081
4082
4083
4084
4085
4086
4087
4088
4089
4090
4091
4092
4093
4094
4095
4096
4097
4098
4099
4100
4101
4102
4103
4104
4105
4106
4107
4108
4109
4110
4111
4112
4113
4114
4115
4116
4117
4118
4119
4120
4121
4122
4123
4124
4125
4126
4127
4128
4129
4130
4131
4132
4133
4134
4135
4136
4137
4138
4139
4140
4141
4142
4143
4144
4145
4146
4147
4148
4149
4150
4151
4152
4153
4154
4155
4156
4157
4158
4159
4160
4161
4162
4163
4164
4165
4166
4167
4168
4169
4170
4171
4172
4173
4174
4175
4176
4177
4178
4179
4180
4181
4182
4183
4184
4185
4186
4187
4188
4189
4190
4191
4192
4193
4194
4195
4196
4197
4198
4199
4200
4201
4202
4203
4204
4205
4206
4207
4208
4209
4210
4211
4212
4213
4214
4215
4216
4217
4218
4219
4220
4221
4222
4223
4224
4225
4226
4227
4228
4229
4230
4231
4232
4233
4234
4235
4236
4237
4238
4239
4240
4241
4242
4243
4244
4245
4246
4247
4248
4249
4250
4251
4252
4253
4254
4255
4256
4257
4258
4259
4260
4261
4262
4263
4264
4265
4266
4267
4268
4269
4270
4271
4272
4273
4274
4275
4276
4277
4278
4279
4280
4281
4282
4283
4284
4285
4286
4287
4288
4289
4290
4291
4292
4293
4294
4295
4296
4297
4298
4299
4300
4301
4302
4303
4304
4305
4306
4307
4308
4309
4310
4311
4312
4313
4314
4315
4316
4317
4318
4319
4320
4321
4322
4323
4324
4325
4326
4327
4328
4329
4330
4331
4332
4333
4334
4335
4336
4337
4338
4339
4340
4341
4342
4343
4344
4345
4346
4347
4348
4349
4350
4351
4352
4353
4354
4355
4356
4357
4358
4359
4360
4361
4362
4363
4364
4365
4366
4367
4368
4369
4370
4371
4372
4373
4374
4375
4376
4377
4378
4379
4380
4381
4382
4383
4384
4385
4386
4387
4388
4389
4390
4391
4392
4393
4394
4395
4396
4397
4398
4399
4400
4401
4402
4403
4404
4405
4406
4407
4408
4409
4410
4411
4412
4413
4414
4415
4416
4417
4418
4419
4420
4421
4422
4423
4424
4425
4426
4427
4428
4429
4430
4431
4432
4433
4434
4435
4436
4437
4438
4439
4440
4441
4442
4443
4444
4445
4446
4447
4448
4449
4450
4451
4452
4453
4454
4455
4456
4457
4458
4459
4460
4461
4462
4463
4464
4465
4466
4467
4468
4469
4470
4471
4472
4473
4474
4475
4476
4477
4478
4479
4480
4481
4482
4483
4484
4485
4486
4487
4488
4489
4490
4491
4492
4493
4494
4495
4496
4497
4498
4499
4500
4501
4502
4503
4504
4505
4506
4507
4508
4509
4510
4511
4512
4513
4514
4515
4516
4517
4518
4519
4520
4521
4522
4523
4524
4525
4526
4527
4528
4529
4530
4531
4532
4533
4534
4535
4536
4537
4538
4539
4540
4541
4542
4543
4544
4545
4546
4547
4548
4549
4550
4551
4552
4553
4554
4555
4556
4557
4558
4559
4560
4561
4562
4563
4564
4565
4566
4567
4568
4569
4570
4571
4572
4573
4574
4575
4576
/* Copyright (C) 2000-2006 MySQL AB

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; version 2 of the License.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA */

/**
  @file

  @brief
  join cache optimizations

  @defgroup Query_Optimizer  Query Optimizer
  @{
*/

#ifdef USE_PRAGMA_IMPLEMENTATION
#pragma implementation				// gcc: Class implementation
#endif

#include "key.h"
#include "sql_base.h"
#include "sql_select.h"
#include "opt_subselect.h"

#define NO_MORE_RECORDS_IN_BUFFER  (uint)(-1)

static void save_or_restore_used_tabs(JOIN_TAB *join_tab, bool save);

/*****************************************************************************
 *  Join cache module
******************************************************************************/

/* 
  Fill in the descriptor of a flag field associated with a join cache    

  SYNOPSIS
    add_field_flag_to_join_cache()
      str           position in a record buffer to copy the field from/to
      length        length of the field 
      field  IN/OUT pointer to the field descriptor to fill in 

  DESCRIPTION
    The function fill in the descriptor of a cache flag field to which
    the parameter 'field' points to. The function uses the first two
    parameters to set the position in the record buffer from/to which 
    the field value is to be copied and the length of the copied fragment. 
    Before returning the result the function increments the value of
    *field by 1.
    The function ignores the fields 'blob_length' and 'ofset' of the
    descriptor.

  RETURN VALUE
    the length of the field  
*/

static
uint add_flag_field_to_join_cache(uchar *str, uint length, CACHE_FIELD **field)
{
  CACHE_FIELD *copy= *field;
  copy->str= str;
  copy->length= length;
  copy->type= 0;
  copy->field= 0;
  copy->referenced_field_no= 0;
  (*field)++;
  return length;    
}


/* 
  Fill in the descriptors of table data fields associated with a join cache    

  SYNOPSIS
    add_table_data_fields_to_join_cache()
      tab              descriptors of fields from this table are to be filled
      field_set        descriptors for only these fields are to be created
      field_cnt IN/OUT     counter of data fields  
      descr  IN/OUT        pointer to the first descriptor to be filled
      field_ptr_cnt IN/OUT counter of pointers to the data fields
      descr_ptr IN/OUT     pointer to the first pointer to blob descriptors 

  DESCRIPTION
    The function fills in the descriptors of cache data fields from the table
    'tab'. The descriptors are filled only for the fields marked in the 
    bitmap 'field_set'. 
    The function fills the descriptors starting from the position pointed
    by 'descr'. If an added field is of a BLOB type then a pointer to the 
    its descriptor is added to the array descr_ptr.   
    At the return 'descr' points to the position after the last added
    descriptor  while 'descr_ptr' points to the position right after the
    last added pointer.  

  RETURN VALUE
    the total length of the added fields  
*/

static
uint add_table_data_fields_to_join_cache(JOIN_TAB *tab, 
                                         MY_BITMAP *field_set,
                                         uint *field_cnt, 
                                         CACHE_FIELD **descr,
                                         uint *field_ptr_cnt,
                                         CACHE_FIELD ***descr_ptr)
{
  Field **fld_ptr;
  uint len= 0;
  CACHE_FIELD *copy= *descr;
  CACHE_FIELD **copy_ptr= *descr_ptr;
  uint used_fields= bitmap_bits_set(field_set);
  for (fld_ptr= tab->table->field; used_fields; fld_ptr++)
  {
    if (bitmap_is_set(field_set, (*fld_ptr)->field_index))
    {
      len+= (*fld_ptr)->fill_cache_field(copy);
      if (copy->type == CACHE_BLOB)
      {
        *copy_ptr= copy;
        copy_ptr++;
        (*field_ptr_cnt)++;
      }
      copy->field= *fld_ptr;
      copy->referenced_field_no= 0;
      copy++;
      (*field_cnt)++;
      used_fields--;
    }
  }
  *descr= copy;
  *descr_ptr= copy_ptr;
  return len;
}

/* 
  Determine different counters of fields associated with a record in the cache  

  SYNOPSIS
    calc_record_fields()

  DESCRIPTION
    The function counts the number of total fields stored in a record
    of the cache and saves this number in the 'fields' member. It also
    determines the number of flag fields and the number of blobs.
    The function sets 'with_match_flag' on if 'join_tab' needs a match flag
    i.e. if it is the first inner table of an outer join or a semi-join.  

  RETURN VALUE
    none 
*/

void JOIN_CACHE::calc_record_fields()
{
  JOIN_TAB *tab;

  if (prev_cache)
    tab= prev_cache->join_tab;
  else
  {
    if (join_tab->bush_root_tab)
    {
      /* 
        --ot1--SJM1--------------ot2--...
                |
                |
                +-it1--...--itN
                        ^____________ this->join_tab is somewhere here, 
                                      inside an sjm nest.

        The join buffer should store the values of it1.*, it2.*, ..
        It should not store values of ot1.*.
      */
      tab= join_tab->bush_root_tab->bush_children->start;
    }
    else
    {
      /*
        -ot1--ot2--SJM1--SJM2--------------ot3--...--otN
                    |     |                      ^   
                    |     +-it21--...--it2N      |
                    |                            \-- we're somewhere here,
                    +-it11--...--it1N                at the top level
        
        The join buffer should store the values of 

          ot1.*, ot2.*, it1{i}, it2{j}.*, ot3.*, ...
        
        that is, we should start from the first non-const top-level table. 

        We will need to store columns of SJ-inner tables (it_X_Y.*), but we're
        not interested in storing the columns of materialization tables
        themselves. Beause of that, if the first non-const top-level table is a
        materialized table, we move to its bush_children:
      */
      tab= join->join_tab + join->const_tables;
      if (tab->bush_children)
        tab= tab->bush_children->start;
    }
  }
  DBUG_ASSERT(!tab->bush_children);

  start_tab= tab;
  fields= 0;
  blobs= 0;
  flag_fields= 0;
  data_field_count= 0;
  data_field_ptr_count= 0;
  referenced_fields= 0;

  /*
    The following loop will get inside SJM nests, because data may be unpacked
    to sjm-inner tables.
  */
  for (; tab != join_tab ; tab= next_linear_tab(join, tab, WITHOUT_BUSH_ROOTS))
  {	    
    tab->calc_used_field_length(FALSE);
    flag_fields+= test(tab->used_null_fields || tab->used_uneven_bit_fields);
    flag_fields+= test(tab->table->maybe_null);
    fields+= tab->used_fields;
    blobs+= tab->used_blobs;

    fields+= tab->check_rowid_field();
  }
  if ((with_match_flag= join_tab->use_match_flag()))
    flag_fields++;
  fields+= flag_fields;
}


/* 
  Collect information on join key arguments  

  SYNOPSIS
    collect_info_on_key_args()

  DESCRIPTION
    The function traverses the ref expressions that are used to access the
    joined table join_tab. For each table 'tab' whose fields are to be stored
    in the join buffer of the cache the function finds the fields from 'tab'
    that occur in the ref expressions and marks these fields in the bitmap
    tab->table->tmp_set. The function counts the number of them stored
    in this cache and the total number of them stored in the previous caches
    and saves the results of the counting in 'local_key_arg_fields' and
    'external_key_arg_fields' respectively.

  NOTES
    The function does not do anything if no key is used to join the records
    from join_tab.
    
  RETURN VALUE
    none 
*/  

void JOIN_CACHE::collect_info_on_key_args()
{
  JOIN_TAB *tab;
  JOIN_CACHE *cache;
  local_key_arg_fields= 0;
  external_key_arg_fields= 0;

  if (!is_key_access())
    return;

  TABLE_REF *ref= &join_tab->ref;
  cache= this;
  do
  {
    for (tab= cache->start_tab; tab != cache->join_tab;
         tab= next_linear_tab(join, tab, WITHOUT_BUSH_ROOTS))
    { 
      uint key_args;
      bitmap_clear_all(&tab->table->tmp_set);
      for (uint i= 0; i < ref->key_parts; i++)
      {
        Item *ref_item= ref->items[i]; 
        if (!(tab->table->map & ref_item->used_tables()))
	  continue;
	 ref_item->walk(&Item::add_field_to_set_processor, 1,
                        (uchar *) tab->table);
      }
      if ((key_args= bitmap_bits_set(&tab->table->tmp_set)))
      {
        if (cache == this)
          local_key_arg_fields+= key_args;
        else
          external_key_arg_fields+= key_args;
      }
    }
    cache= cache->prev_cache;
  } 
  while (cache);

  return;
}


/* 
  Allocate memory for descriptors and pointers to them associated with the cache  

  SYNOPSIS
    alloc_fields()

  DESCRIPTION
    The function allocates memory for the array of fields descriptors
    and the array of pointers to the field descriptors used to copy
    join record data from record buffers into the join buffer and
    backward. Some pointers refer to the field descriptor associated
    with previous caches. They are placed at the beginning of the array
    of pointers and its total number is stored in external_key_arg_fields.
    The pointer of the first array is assigned to field_descr and the number
    of the elements in it is precalculated by the function calc_record_fields. 
    The allocated arrays are adjacent.
  
  NOTES
    The memory is allocated in join->thd->memroot

  RETURN VALUE
    pointer to the first array  
*/

int JOIN_CACHE::alloc_fields()
{
  uint ptr_cnt= external_key_arg_fields+blobs+1;
  uint fields_size= sizeof(CACHE_FIELD)*fields;
  field_descr= (CACHE_FIELD*) sql_alloc(fields_size +
                                        sizeof(CACHE_FIELD*)*ptr_cnt);
  blob_ptr= (CACHE_FIELD **) ((uchar *) field_descr + fields_size);
  return (field_descr == NULL);
}  


/* 
  Create descriptors of the record flag fields stored in the join buffer 

  SYNOPSIS
    create_flag_fields()

  DESCRIPTION
    The function creates descriptors of the record flag fields stored
    in the join buffer. These are descriptors for:
    - an optional match flag field,
    - table null bitmap fields, 
    - table null row fields.
    The match flag field is created when 'join_tab' is the first inner
    table of an outer join our a semi-join. A null bitmap field is
    created for any table whose fields are to be stored in the join
    buffer if at least one of these fields is nullable or is a BIT field
    whose bits are partially stored with null bits. A null row flag
    is created for any table assigned to the cache if it is an inner
    table of an outer join.
    The descriptor for flag fields are placed one after another at the
    beginning of the array of field descriptors 'field_descr' that
    contains 'fields' elements. If there is a match flag field the 
    descriptor for it is always first in the sequence of flag fields.
    The descriptors for other flag fields can follow in an arbitrary
    order. 
    The flag field values follow in a record stored in the join buffer
    in the same order as field descriptors, with the match flag always
    following first.
    The function sets the value of 'flag_fields' to the total number
    of the descriptors created for the flag fields.
    The function sets the value of 'length' to the total length of the
    flag fields.
  
  RETURN VALUE
    none
*/

void JOIN_CACHE::create_flag_fields()
{
  CACHE_FIELD *copy;
  JOIN_TAB *tab;

  copy= field_descr;

  length=0;

  /* If there is a match flag the first field is always used for this flag */ 
  if (with_match_flag)
    length+= add_flag_field_to_join_cache((uchar*) &join_tab->found,
                                          sizeof(join_tab->found),
	                                  &copy);

  /* Create fields for all null bitmaps and null row flags that are needed */
  for (tab= start_tab; tab != join_tab; 
       tab= next_linear_tab(join, tab, WITHOUT_BUSH_ROOTS))
  {
    TABLE *table= tab->table;

    /* Create a field for the null bitmap from table if needed */
    if (tab->used_null_fields || tab->used_uneven_bit_fields)			    
      length+= add_flag_field_to_join_cache(table->null_flags,
                                            table->s->null_bytes,
                                            &copy);
 
    /* Create table for the null row flag if needed */
    if (table->maybe_null)
      length+= add_flag_field_to_join_cache((uchar*) &table->null_row,
                                            sizeof(table->null_row),
                                            &copy);
  }

  /* Theoretically the new value of flag_fields can be less than the old one */   
  flag_fields= copy-field_descr;
}


/* 
  Create descriptors of the fields used to build access keys to the joined table

  SYNOPSIS
    create_key_arg_fields()

  DESCRIPTION
    The function creates descriptors of the record fields stored in the join
    buffer that are used to build access keys to the joined table. These
    fields are put into the buffer ahead of other records fields stored in
    the buffer. Such placement helps to optimize construction of access keys.
    For each field that is used to build access keys to the joined table but
    is stored in some other join cache buffer the function saves a pointer
    to the the field descriptor. The array of such pointers are placed in the
    the join cache structure just before the array of pointers to the
    blob fields blob_ptr.
    Any field stored in a join cache buffer that is used to construct keys
    to access tables associated with other join caches is called a referenced
    field. It receives a unique number that is saved by the function in the
    member 'referenced_field_no' of the CACHE_FIELD descriptor for the field.
    This number is used as index to the array of offsets to the referenced
    fields that are saved and put in the join cache buffer after all record
    fields.
    The function also finds out whether that the keys to access join_tab
    can be considered as embedded and, if so, sets the flag 'use_emb_key' in
    this join cache appropriately. 
     
  NOTES.
    When a key to access the joined table 'join_tab' is constructed the array
    of pointers to the field descriptors for the external fields is looked
    through. For each of this pointers we find out in what previous key cache
    the referenced field is stored. The value of 'referenced_field_no'
    provides us with the index into the array of offsets for referenced 
    fields stored in the join cache. The offset read by the the index allows
    us to read the field without reading all other fields of the record 
    stored the join cache buffer. This optimizes the construction of keys
    to access 'join_tab' when some key arguments are stored in the previous
    join caches.  

  NOTES
    The function does not do anything if no key is used to join the records
    from join_tab.
 
  RETURN VALUE
    none
*/
void JOIN_CACHE::create_key_arg_fields()
{
  JOIN_TAB *tab;
  JOIN_CACHE *cache;

  if (!is_key_access())
    return;

  /* 
    Save pointers to the cache fields in previous caches
    that  are used to build keys for this key access.
  */
  cache= this;
  uint ext_key_arg_cnt= external_key_arg_fields;
  CACHE_FIELD *copy;
  CACHE_FIELD **copy_ptr= blob_ptr;
  while (ext_key_arg_cnt)
  {
    cache= cache->prev_cache;
    for (tab= cache->start_tab; tab != cache->join_tab; 
         tab= next_linear_tab(join, tab, WITHOUT_BUSH_ROOTS))
    { 
      CACHE_FIELD *copy_end;
      MY_BITMAP *key_read_set= &tab->table->tmp_set;
      /* key_read_set contains the bitmap of tab's fields referenced by ref */ 
      if (bitmap_is_clear_all(key_read_set))
        continue;
      copy_end= cache->field_descr+cache->fields;
      for (copy= cache->field_descr+cache->flag_fields; copy < copy_end; copy++)
      {
        /*
          (1) - when we store rowids for DuplicateWeedout, they have
                copy->field==NULL
        */
        if (copy->field &&  // (1)
            copy->field->table == tab->table &&
            bitmap_is_set(key_read_set, copy->field->field_index))
        {
          *copy_ptr++= copy; 
          ext_key_arg_cnt--;
          if (!copy->referenced_field_no)
          {
            /* 
              Register the referenced field 'copy': 
              - set the offset number in copy->referenced_field_no,
              - adjust the value of the flag 'with_length',
              - adjust the values of 'pack_length' and 
                of 'pack_length_with_blob_ptrs'.
	    */
            copy->referenced_field_no= ++cache->referenced_fields;
            if (!cache->with_length)
            {
              cache->with_length= TRUE;
              uint sz= cache->get_size_of_rec_length();
              cache->base_prefix_length+= sz;
              cache->pack_length+= sz;
              cache->pack_length_with_blob_ptrs+= sz;
            }
	    cache->pack_length+= cache->get_size_of_fld_offset();
            cache->pack_length_with_blob_ptrs+= cache->get_size_of_fld_offset();
          }        
        }
      }
    } 
  }
  /* After this 'blob_ptr' shall not be be changed */ 
  blob_ptr= copy_ptr;
  
  /* Now create local fields that are used to build ref for this key access */
  copy= field_descr+flag_fields;
  for (tab= start_tab; tab != join_tab; 
       tab= next_linear_tab(join, tab, WITHOUT_BUSH_ROOTS))
  {
    length+= add_table_data_fields_to_join_cache(tab, &tab->table->tmp_set,
                                                 &data_field_count, &copy,
                                                 &data_field_ptr_count, 
                                                 &copy_ptr);
  }

  use_emb_key= check_emb_key_usage();

  return;
}


/* 
  Create descriptors of all remaining data fields stored in the join buffer    

  SYNOPSIS
    create_remaining_fields()

  DESCRIPTION
    The function creates descriptors for all remaining data fields of a
    record from the join buffer. If the value returned by is_key_access() is
    false the function creates fields for all read record fields that
    comprise the partial join record joined with join_tab. Otherwise, 
    for each table tab, the set of the read fields for which the descriptors
    have to be added is determined as the difference between all read fields
    and and those for which the descriptors have been already created.
    The latter are supposed to be marked in the bitmap tab->table->tmp_set.
    The function increases the value of 'length' to the the total length of
    the added fields.
   
  NOTES
    If is_key_access() returns true the function modifies the value of
    tab->table->tmp_set for a each table whose fields are stored in the cache.
    The function calls the method Field::fill_cache_field to figure out
    the type of the cache field and the maximal length of its representation
    in the join buffer. If this is a blob field then additionally a pointer
    to this field is added as an element of the array blob_ptr. For a blob
    field only the size of the length of the blob data is taken into account.
    It is assumed that 'data_field_count' contains the number of descriptors
    for data fields that have been already created and 'data_field_ptr_count'
    contains the number of the pointers to such descriptors having been
    stored up to the moment.

  RETURN VALUE
    none 
*/

void JOIN_CACHE::create_remaining_fields()
{
  JOIN_TAB *tab;
  bool all_read_fields= !is_key_access();
  CACHE_FIELD *copy= field_descr+flag_fields+data_field_count;
  CACHE_FIELD **copy_ptr= blob_ptr+data_field_ptr_count;

  for (tab= start_tab; tab != join_tab; 
       tab= next_linear_tab(join, tab, WITHOUT_BUSH_ROOTS))
  {
    MY_BITMAP *rem_field_set;
    TABLE *table= tab->table;

    if (all_read_fields)
      rem_field_set= table->read_set;
    else
    {
      bitmap_invert(&table->tmp_set);
      bitmap_intersect(&table->tmp_set, table->read_set);
      rem_field_set= &table->tmp_set;
    }  

    length+= add_table_data_fields_to_join_cache(tab, rem_field_set,
                                                 &data_field_count, &copy,
                                                 &data_field_ptr_count,
                                                 &copy_ptr);
  
    /* SemiJoinDuplicateElimination: allocate space for rowid if needed */
    if (tab->keep_current_rowid)
    {
      copy->str= table->file->ref;
      if (copy->str)
        copy->length= table->file->ref_length;
      else
      {
        /* This may happen only for materialized derived tables and views */
        copy->length= 0;
        copy->str= (uchar *) table;
      } 
      copy->type= CACHE_ROWID;
      copy->field= 0;
      copy->referenced_field_no= 0;
      length+= copy->length;
      data_field_count++;
      copy++;
    }
  }
}



/* 
  Calculate and set all cache constants      

  SYNOPSIS
    set_constants()

  DESCRIPTION
    The function calculates and set all precomputed constants that are used
    when writing records into the join buffer and reading them from it.
    It calculates the size of offsets of a record within the join buffer
    and of a field within a record. It also calculates the number of bytes
    used to store record lengths.
    The function also calculates the maximal length of the representation
    of record in the cache excluding blob_data. This value is used when
    making a dicision whether more records should be added into the join
    buffer or not.
  
  RETURN VALUE
    none 
*/

void JOIN_CACHE::set_constants()
{ 
  /* 
    Any record from a BKA cache is prepended with the record length.
    We use the record length when reading the buffer and building key values
    for each record. The length allows us not to read the fields that are
    not needed for keys.
    If a record has match flag it also may be skipped when the match flag
    is on. It happens if the cache is used for a semi-join operation or
    for outer join when the 'not exist' optimization can be applied.
    If some of the fields are referenced from other caches then
    the record length allows us to easily reach the saved offsets for
    these fields since the offsets are stored at the very end of the record.
    However at this moment we don't know whether we have referenced fields for
    the cache or not. Later when a referenced field is registered for the cache
    we adjust the value of the flag 'with_length'.
  */ 
  with_length= is_key_access() || 
               join_tab->is_inner_table_of_semi_join_with_first_match() ||
               join_tab->is_inner_table_of_outer_join();
  /* 
     At this moment we don't know yet the value of 'referenced_fields',
     but in any case it can't be greater than the value of 'fields'.
  */
  uint len= length + fields*sizeof(uint)+blobs*sizeof(uchar *) +
            (prev_cache ? prev_cache->get_size_of_rec_offset() : 0) +
            sizeof(ulong);
  buff_size= max(join->thd->variables.join_buff_size, 2*len);
  size_of_rec_ofs= offset_size(buff_size);
  size_of_rec_len= blobs ? size_of_rec_ofs : offset_size(len); 
  size_of_fld_ofs= size_of_rec_len;
  base_prefix_length= (with_length ? size_of_rec_len : 0) +
                      (prev_cache ? prev_cache->get_size_of_rec_offset() : 0);
  /* 
    The size of the offsets for referenced fields will be added later.
    The values of 'pack_length' and 'pack_length_with_blob_ptrs' are adjusted
    every time when the first reference to the referenced field is registered.
  */
  pack_length= (with_length ? size_of_rec_len : 0) +
               (prev_cache ? prev_cache->get_size_of_rec_offset() : 0) + 
               length;
  pack_length_with_blob_ptrs= pack_length + blobs*sizeof(uchar *);
}


/* 
  Get maximum total length of all affixes of a record in the join cache buffer

  SYNOPSIS
    get_record_max_affix_length()

  DESCRIPTION
    The function calculates the maximum possible total length of all affixes
    of a record in the join cache buffer, that is made of:
      - the length of all prefixes used in this cache,
      - the length of the match flag if it's needed
      - the total length of the maximum possible offsets to the fields of
        a record in the buffer.

  RETURN VALUE
    The maximum total length of all affixes of a record in the join buffer  
*/ 
     
uint JOIN_CACHE::get_record_max_affix_length()
{
  uint len= get_prefix_length() +
            test(with_match_flag) + 
            size_of_fld_ofs * data_field_count;
  return len;
}


/* 
  Get the minimum possible size of the cache join buffer 

  SYNOPSIS
    get_min_join_buffer_size()

  DESCRIPTION
    At the first its invocation for the cache the function calculates the
    minimum possible size of the join buffer of the cache. This value depends
    on the minimal number of records 'min_records' to be stored in the join
    buffer. The number is supposed to be determined by the procedure that 
    chooses the best access path to the joined table join_tab in the execution
    plan. After the calculation of the interesting size the function saves it
    in the field 'min_buff_size' in order to use it directly at the next     
    invocations of the function.

  NOTES
    Currently the number of minimal records is just set to 1.

  RETURN VALUE
    The minimal possible size of the join buffer of this cache 
*/

ulong JOIN_CACHE::get_min_join_buffer_size()
{
  if (!min_buff_size)
  {
    size_t len= 0;
    for (JOIN_TAB *tab= start_tab; tab != join_tab; 
         tab= next_linear_tab(join, tab, WITHOUT_BUSH_ROOTS))
    {
      len+= tab->get_max_used_fieldlength();
    }
    len+= get_record_max_affix_length() + get_max_key_addon_space_per_record();  
    size_t min_sz= len*min_records;
    size_t add_sz= 0;
    for (uint i=0; i < min_records; i++)
      add_sz+= join_tab_scan->aux_buffer_incr(i+1);
    avg_aux_buffer_incr= add_sz/min_records;
    min_sz+= add_sz;
    min_sz+= pack_length_with_blob_ptrs;
    set_if_bigger(min_sz, 1);
    min_buff_size= min_sz;
  }
  return min_buff_size;
}


/* 
  Get the maximum possible size of the cache join buffer 

  SYNOPSIS
    get_max_join_buffer_size()

    optimize_buff_size  FALSE <-> do not take more memory than needed for
                        the estimated number of records in the partial join 

  DESCRIPTION
    At the first its invocation for the cache the function calculates the
    maximum possible size of join buffer for the cache. If the parameter
    optimize_buff_size true then this value does not exceed the size of the
    space needed for the estimated number of records 'max_records' in the
    partial join that joins tables from the first one through join_tab. This
    value is also capped off by the value of join_tab->join_buffer_size_limit,
    if it has been set a to non-zero value, and by the value of the system
    parameter join_buffer_size - otherwise. After the calculation of the
    interesting size the function saves the value in the field 'max_buff_size'
    in order to use it directly at the next  invocations of the function.

  NOTES
    Currently the value of join_tab->join_buffer_size_limit is initialized
    to 0 and is never reset.

  RETURN VALUE
    The maximum possible size of the join buffer of this cache 
*/

ulong JOIN_CACHE::get_max_join_buffer_size(bool optimize_buff_size)
{
  if (!max_buff_size)
  {
    size_t max_sz;
    size_t min_sz= get_min_join_buffer_size(); 
    size_t len= 0;
    for (JOIN_TAB *tab= start_tab; tab != join_tab;
         tab= next_linear_tab(join, tab, WITHOUT_BUSH_ROOTS))
    {
      len+= tab->get_used_fieldlength();
    }
    len+= get_record_max_affix_length();
    avg_record_length= len;
    len+= get_max_key_addon_space_per_record() + avg_aux_buffer_incr;
    space_per_record= len;
    
    size_t limit_sz= join->thd->variables.join_buff_size;
    if (join_tab->join_buffer_size_limit)
      set_if_smaller(limit_sz, join_tab->join_buffer_size_limit);
    if (!optimize_buff_size)
      max_sz= limit_sz;
    else
    {    
      if (limit_sz / max_records > space_per_record)
        max_sz= space_per_record * max_records;
      else
        max_sz= limit_sz;
      max_sz+= pack_length_with_blob_ptrs;
      set_if_smaller(max_sz, limit_sz);
    }
    set_if_bigger(max_sz, min_sz);
    max_buff_size= max_sz;
  }
  return max_buff_size;
}    
      

/* 
  Allocate memory for a join buffer      

  SYNOPSIS
    alloc_buffer()

  DESCRIPTION
    The function allocates a lump of memory for the cache join buffer. 
    Initially the function sets the size of the buffer buff_size equal to
    the value returned by get_max_join_buffer_size(). If the total size of
    the space intended to be used for the join buffers employed by the
    tables from the first one through join_tab exceeds the value of the
    system parameter join_buff_space_limit, then the function first tries
    to shrink the used buffers to make the occupied space fit the maximum
    memory allowed to be used for all join buffers in total. After
    this the function tries to allocate a join buffer for join_tab.
    If it fails to do so, it decrements the requested size of the join
    buffer, shrinks proportionally the join buffers used for the previous
    tables and tries to allocate a buffer for join_tab. In the case of a
    failure the function repeats its attempts with smaller and smaller
    requested sizes of the buffer, but not more than 4 times.
  
  RETURN VALUE
    0   if the memory has been successfully allocated
    1   otherwise
*/

int JOIN_CACHE::alloc_buffer()
{
  JOIN_TAB *tab;
  JOIN_CACHE *cache;
  ulonglong curr_buff_space_sz= 0;
  ulonglong curr_min_buff_space_sz= 0;
  ulonglong join_buff_space_limit=
    join->thd->variables.join_buff_space_limit;
  bool optimize_buff_size= 
         optimizer_flag(join->thd, OPTIMIZER_SWITCH_OPTIMIZE_JOIN_BUFFER_SIZE);
  double partial_join_cardinality=  (join_tab-1)->get_partial_join_cardinality();
  buff= NULL;
  min_buff_size= 0;
  max_buff_size= 0;
  min_records= 1;
  max_records= (size_t) (partial_join_cardinality <= join_buff_space_limit ?
                 (ulonglong) partial_join_cardinality : join_buff_space_limit);
  set_if_bigger(max_records, 10);
  min_buff_size= get_min_join_buffer_size();
  buff_size= get_max_join_buffer_size(optimize_buff_size);

  for (tab= start_tab; tab!= join_tab; 
       tab= next_linear_tab(join, tab, WITHOUT_BUSH_ROOTS))
  {
    cache= tab->cache;
    if (cache)
    {
      curr_min_buff_space_sz+= cache->get_min_join_buffer_size();
      curr_buff_space_sz+= cache->get_join_buffer_size();
    }
  }

  if (curr_min_buff_space_sz > join_buff_space_limit ||
      (curr_buff_space_sz > join_buff_space_limit &&
       (!optimize_buff_size || 
        join->shrink_join_buffers(join_tab, curr_buff_space_sz,
                                  join_buff_space_limit))))
    goto fail;
                               
  for (ulong buff_size_decr= (buff_size-min_buff_size)/4 + 1; ; )
  {
    ulong next_buff_size;

    if ((buff= (uchar*) my_malloc(buff_size, MYF(0))))
      break;

    next_buff_size= buff_size > buff_size_decr ? buff_size-buff_size_decr : 0;
    if (next_buff_size < min_buff_size ||
        join->shrink_join_buffers(join_tab, curr_buff_space_sz,
                                  curr_buff_space_sz-buff_size_decr))
      goto fail;
    buff_size= next_buff_size;

    curr_buff_space_sz= 0;
    for (tab= join->join_tab+join->const_tables; tab <= join_tab; tab++)
    {
      cache= tab->cache;
      if (cache)
        curr_buff_space_sz+= cache->get_join_buffer_size();
    } 
  }
  return 0;

fail:
  buff_size= 0;
  return 1;
}

 
/*
  Shrink the size if the cache join buffer in a given ratio

  SYNOPSIS
    shrink_join_buffer_in_ratio()
      n           nominator of the ratio to shrink the buffer in
      d           denominator if the ratio

  DESCRIPTION
    The function first deallocates the join buffer of the cache. Then
    it allocates a buffer that is (n/d) times smaller.
    
  RETURN VALUE
    FALSE   on success with allocation of the smaller join buffer 
    TRUE    otherwise       
*/

bool JOIN_CACHE::shrink_join_buffer_in_ratio(ulonglong n, ulonglong d)
{
  size_t next_buff_size;
  if (n < d)
    return FALSE;
  next_buff_size= (size_t) ((double) buff_size / n * d);
  set_if_bigger(next_buff_size, min_buff_size);
  buff_size= next_buff_size;
  return realloc_buffer();
}  


/*
  Reallocate the join buffer of a join cache
 
  SYNOPSIS
    realloc_buffer()

  DESCRITION
    The function reallocates the join buffer of the join cache. After this
    it resets the buffer for writing.

  NOTES
    The function assumes that buff_size contains the new value for the join
    buffer size.  

  RETURN VALUE
    0   if the buffer has been successfully reallocated
    1   otherwise
*/

int JOIN_CACHE::realloc_buffer()
{
  int rc;
  free();
  rc= test(!(buff= (uchar*) my_malloc(buff_size, MYF(0))));
  reset(TRUE);
  return rc;   	
}
  

/* 
  Initialize a join cache       

  SYNOPSIS
    init()

  DESCRIPTION
    The function initializes the join cache structure. It supposed to be called
    by init methods for classes derived from the JOIN_CACHE.
    The function allocates memory for the join buffer and for descriptors of
    the record fields stored in the buffer.

  NOTES
    The code of this function should have been included into the constructor
    code itself. However the new operator for the class JOIN_CACHE would
    never fail while memory allocation for the join buffer is not absolutely
    unlikely to fail. That's why this memory allocation has to be placed in a
    separate function that is called in a couple with a cache constructor.
    It is quite natural to put almost all other constructor actions into
    this function.     
  
  RETURN VALUE
    0   initialization with buffer allocations has been succeeded
    1   otherwise
*/

int JOIN_CACHE::init()
{
  DBUG_ENTER("JOIN_CACHE::init");

  calc_record_fields();

  collect_info_on_key_args();

  if (alloc_fields())
    DBUG_RETURN(1);

  create_flag_fields();

  create_key_arg_fields();

  create_remaining_fields();

  set_constants();

  if (alloc_buffer())
    DBUG_RETURN(1); 
  
  reset(TRUE); 

  DBUG_RETURN(0);
}


/* 
  Check the possibility to read the access keys directly from the join buffer       
  SYNOPSIS
    check_emb_key_usage()

  DESCRIPTION
    The function checks some conditions at which the key values can be read
    directly from the join buffer. This is possible when the key values can be
    composed by concatenation of the record fields stored in the join buffer.
    Sometimes when the access key is multi-component the function has to re-order
    the fields written into the join buffer to make keys embedded. If key 
    values for the key access are detected as embedded then 'use_emb_key'
    is set to TRUE.

  EXAMPLE
    Let table t2 has an index defined on the columns a,b . Let's assume also
    that the columns t2.a, t2.b as well as the columns t1.a, t1.b are all
    of the integer type. Then if the query
      SELECT COUNT(*) FROM t1, t2 WHERE t1.a=t2.a and t1.b=t2.b  
    is executed with a join cache in such a way that t1 is the driving
    table then the key values to access table t2 can be read directly
    from the join buffer.
  
  NOTES
    In some cases key values could be read directly from the join buffer but
    we still do not consider them embedded. In the future we'll expand the
    the class of keys which we identify as embedded.

  NOTES
    The function returns FALSE if no key is used to join the records
    from join_tab.

  RETURN VALUE
    TRUE    key values will be considered as embedded,
    FALSE   otherwise.
*/

bool JOIN_CACHE::check_emb_key_usage()
{

  if (!is_key_access())
    return FALSE;

  uint i;
  Item *item; 
  KEY_PART_INFO *key_part;
  CACHE_FIELD *copy;
  CACHE_FIELD *copy_end;
  uint len= 0;
  TABLE_REF *ref= &join_tab->ref;
  KEY *keyinfo= join_tab->get_keyinfo_by_key_no(ref->key);

  /* 
    If some of the key arguments are not from the local cache the key
    is not considered as embedded.
    TODO:
    Expand it to the case when ref->key_parts=1 and local_key_arg_fields=0.
  */  
  if (external_key_arg_fields != 0)
    return FALSE;
  /* 
    If the number of the local key arguments is not equal to the number
    of key parts the key value cannot be read directly from the join buffer.   
  */
  if (local_key_arg_fields != ref->key_parts)
    return FALSE;

  /* 
    A key is not considered embedded if one of the following is true:
    - one of its key parts is not equal to a field
    - it is a partial key
    - definition of the argument field does not coincide with the
      definition of the corresponding key component
    - some of the key components are nullable
  */  
  for (i=0; i < ref->key_parts; i++)
  {
    item= ref->items[i]->real_item();
    if (item->type() != Item::FIELD_ITEM)
      return FALSE;
    key_part= keyinfo->key_part+i;
    if (key_part->key_part_flag & HA_PART_KEY_SEG)
      return FALSE;
    if (!key_part->field->eq_def(((Item_field *) item)->field))
      return FALSE;
    if (key_part->field->maybe_null())
      return FALSE;
  }
  
  copy= field_descr+flag_fields;
  copy_end= copy+local_key_arg_fields;
  for ( ; copy < copy_end; copy++)
  {
    /* 
      If some of the key arguments are of variable length the key
      is not considered as embedded.
    */
    if (copy->type != 0)
      return FALSE;
    /* 
      If some of the key arguments are bit fields whose bits are partially
      stored with null bits the key is not considered as embedded.
    */
    if (copy->field->type() == MYSQL_TYPE_BIT &&
	 ((Field_bit*) (copy->field))->bit_len)
      return FALSE;
    len+= copy->length;
  }

  emb_key_length= len;

  /* 
    Make sure that key fields follow the order of the corresponding
    key components these fields are equal to. For this the descriptors
    of the fields that comprise the key might be re-ordered.
  */
  for (i= 0; i < ref->key_parts; i++)
  {
    uint j;
    Item *item= ref->items[i]->real_item();
    Field *fld= ((Item_field *) item)->field;
    CACHE_FIELD *init_copy= field_descr+flag_fields+i; 
    for (j= i, copy= init_copy; i < local_key_arg_fields;  i++, copy++)
    {
      if (fld->eq(copy->field))
      {
        if (j != i)
        {
          CACHE_FIELD key_part_copy= *copy;
          *copy= *init_copy;
          *init_copy= key_part_copy;
        }
        break;
      }
    }
  }

  return TRUE;
}    


/* 
  Write record fields and their required offsets into the join cache buffer

  SYNOPSIS
    write_record_data()
      link        a reference to the associated info in the previous cache
      is_full OUT true if it has been decided that no more records will be
                  added to the join buffer

  DESCRIPTION
    This function put into the cache buffer the following info that it reads
    from the join record buffers or computes somehow:
    (1) the length of all fields written for the record (optional)
    (2) an offset to the associated info in the previous cache (if there is any)
        determined by the link parameter
    (3) all flag fields of the tables whose data field are put into the cache:
        - match flag (optional),
        - null bitmaps for all tables,
        - null row flags for all tables
    (4) values of all data fields including
        - full images of those fixed legth data fields that cannot have 
          trailing spaces
        - significant part of fixed length fields that can have trailing spaces
          with the prepanded length 
        - data of non-blob variable length fields with the prepanded data length  
        - blob data from blob fields with the prepanded data length
    (5) record offset values for the data fields that are referred to from 
        other caches
 
    The record is written at the current position stored in the field 'pos'.
    At the end of the function 'pos' points at the position right after the 
    written record data.
    The function increments the number of records in the cache that is stored
    in the 'records' field by 1. The function also modifies the values of
    'curr_rec_pos' and 'last_rec_pos' to point to the written record.
    The 'end_pos' cursor is modified accordingly.
    The 'last_rec_blob_data_is_in_rec_buff' is set on if the blob data 
    remains in the record buffers and not copied to the join buffer. It may
    happen only to the blob data from the last record added into the cache.
    If on_precond is attached to join_tab and it is not evaluated to TRUE
    then MATCH_IMPOSSIBLE is placed in the match flag field of the record
    written into the join buffer.
       
  RETURN VALUE
    length of the written record data
*/

uint JOIN_CACHE::write_record_data(uchar * link, bool *is_full)
{
  uint len;
  bool last_record;
  CACHE_FIELD *copy;
  CACHE_FIELD *copy_end;
  uchar *flags_pos;
  uchar *cp= pos;
  uchar *init_pos= cp;
  uchar *rec_len_ptr= 0;
  uint key_extra= extra_key_length();
 
  records++;  /* Increment the counter of records in the cache */

  len= pack_length + key_extra;

  /* Make an adjustment for the size of the auxiliary buffer if there is any */
  uint incr= aux_buffer_incr(records);
  size_t rem= rem_space();
  aux_buff_size+= len+incr < rem ? incr : rem;

  /*
    For each blob to be put into cache save its length and a pointer
    to the value in the corresponding element of the blob_ptr array.
    Blobs with null values are skipped.
    Increment 'len' by the total length of all these blobs. 
  */    
  if (blobs)
  {
    CACHE_FIELD **copy_ptr= blob_ptr;
    CACHE_FIELD **copy_ptr_end= copy_ptr+blobs;
    for ( ; copy_ptr < copy_ptr_end; copy_ptr++)
    {
      Field_blob *blob_field= (Field_blob *) (*copy_ptr)->field;
      if (!blob_field->is_null())
      {
        uint blob_len= blob_field->get_length();
        (*copy_ptr)->blob_length= blob_len;
        len+= blob_len;
        blob_field->get_ptr(&(*copy_ptr)->str);
      }
    }
  }

  /*
    Check whether we won't be able to add any new record into the cache after
    this one because the cache will be full. Set last_record to TRUE if it's so.
    The assume that the cache will be full after the record has been written
    into it if either the remaining space of the cache is not big enough for the 
    record's blob values or if there is a chance that not all non-blob fields
    of the next record can be placed there.
    This function is called only in the case when there is enough space left in
    the cache to store at least non-blob parts of the current record.
  */
  last_record= (len+pack_length_with_blob_ptrs+key_extra) > rem_space();
  
  /* 
    Save the position for the length of the record in the cache if it's needed.
    The length of the record will be inserted here when all fields of the record
    are put into the cache.  
  */
  if (with_length)
  {
    rec_len_ptr= cp;   
    cp+= size_of_rec_len;
  }

  /*
    Put a reference to the fields of the record that are stored in the previous
    cache if there is any. This reference is passed by the 'link' parameter.     
  */
  if (prev_cache)
  {
    cp+= prev_cache->get_size_of_rec_offset();
    prev_cache->store_rec_ref(cp, link);
  } 

  curr_rec_pos= cp;
  
  /* If the there is a match flag set its value to 0 */
  copy= field_descr;
  if (with_match_flag)
    *copy[0].str= 0;

  /* First put into the cache the values of all flag fields */
  copy_end= field_descr+flag_fields;
  flags_pos= cp;
  for ( ; copy < copy_end; copy++)
  {
    memcpy(cp, copy->str, copy->length);
    cp+= copy->length;
  } 
  
  /* Now put the values of the remaining fields as soon as they are not nulls */ 
  copy_end= field_descr+fields;
  for ( ; copy < copy_end; copy++)
  {
    Field *field= copy->field;
    if (field && field->maybe_null() && field->is_null())
    {    
      if (copy->referenced_field_no)
        copy->offset= 0;
      continue;              
    }
    /* Save the offset of the field to put it later at the end of the record */ 
    if (copy->referenced_field_no)
      copy->offset= cp-curr_rec_pos;

    if (copy->type == CACHE_BLOB)
    {
      Field_blob *blob_field= (Field_blob *) copy->field;
      if (last_record)
      {
        last_rec_blob_data_is_in_rec_buff= 1;
        /* Put down the length of the blob and the pointer to the data */  
	blob_field->get_image(cp, copy->length+sizeof(char*),
                              blob_field->charset());
	cp+= copy->length+sizeof(char*);
      }
      else
      {
        /* First put down the length of the blob and then copy the data */ 
	blob_field->get_image(cp, copy->length, 
			      blob_field->charset());
	memcpy(cp+copy->length, copy->str, copy->blob_length);               
	cp+= copy->length+copy->blob_length;
      }
    }
    else
    {
      switch (copy->type) {
      case CACHE_VARSTR1:
        /* Copy the significant part of the short varstring field */ 
        len= (uint) copy->str[0] + 1;
        memcpy(cp, copy->str, len);
        cp+= len;
        break;
      case CACHE_VARSTR2:
        /* Copy the significant part of the long varstring field */
        len= uint2korr(copy->str) + 2;
        memcpy(cp, copy->str, len);
        cp+= len;
        break;
      case CACHE_STRIPPED:
      {
        /* 
          Put down the field value stripping all trailing spaces off.
          After this insert the length of the written sequence of bytes.
        */ 
	uchar *str, *end;
	for (str= copy->str, end= str+copy->length;
	     end > str && end[-1] == ' ';
	     end--) ;
	len=(uint) (end-str);
        int2store(cp, len);
	memcpy(cp+2, str, len);
	cp+= len+2;
        break;
      }
      case CACHE_ROWID:
        if (!copy->length)
	{
          /*
            This may happen only for ROWID fields of materialized
            derived tables and views.
	  */
	  TABLE *table= (TABLE *) copy->str;
          copy->str= table->file->ref;
          copy->length= table->file->ref_length;
        }
        /* fall through */
      default:      
        /* Copy the entire image of the field from the record buffer */
	memcpy(cp, copy->str, copy->length);
	cp+= copy->length;
      }
    }
  }
  
  /* Add the offsets of the fields that are referenced from other caches */ 
  if (referenced_fields)
  {
    uint cnt= 0;
    for (copy= field_descr+flag_fields; copy < copy_end ; copy++)
    {
      if (copy->referenced_field_no)
      {
        store_fld_offset(cp+size_of_fld_ofs*(copy->referenced_field_no-1),
                         copy->offset);
        cnt++;
      }
    }
    cp+= size_of_fld_ofs*cnt;
  }

  if (rec_len_ptr)
    store_rec_length(rec_len_ptr, (ulong) (cp-rec_len_ptr-size_of_rec_len));
  last_rec_pos= curr_rec_pos; 
  end_pos= pos= cp;
  *is_full= last_record;

  last_written_is_null_compl= 0;   
  if (!join_tab->first_unmatched && join_tab->on_precond)
  { 
    join_tab->found= 0;
    join_tab->not_null_compl= 1;
    if (!join_tab->on_precond->val_int())
    {
      flags_pos[0]= MATCH_IMPOSSIBLE;     
      last_written_is_null_compl= 1;
    }
  } 
      
  return (uint) (cp-init_pos);
}


/* 
  Reset the join buffer for reading/writing: default implementation

  SYNOPSIS
    reset()
      for_writing  if it's TRUE the function reset the buffer for writing

  DESCRIPTION
    This default implementation of the virtual function reset() resets 
    the join buffer for reading or writing.
    If the buffer is reset for reading only the 'pos' value is reset
    to point to the very beginning of the join buffer. If the buffer is
    reset for writing additionally: 
    - the counter of the records in the buffer is set to 0,
    - the the value of 'last_rec_pos' gets pointing at the position just
      before the buffer, 
    - 'end_pos' is set to point to the beginning of the join buffer,
    - the size of the auxiliary buffer is reset to 0,
    - the flag 'last_rec_blob_data_is_in_rec_buff' is set to 0.
    
  RETURN VALUE
    none
*/
void JOIN_CACHE::reset(bool for_writing)
{
  pos= buff;
  curr_rec_link= 0;
  if (for_writing)
  {
    records= 0;
    last_rec_pos= buff;
    aux_buff_size= 0;
    end_pos= pos;
    last_rec_blob_data_is_in_rec_buff= 0;
  }
}


/* 
  Add a record into the join buffer: the default implementation

  SYNOPSIS
    put_record()

  DESCRIPTION
    This default implementation of the virtual function put_record writes
    the next matching record into the join buffer.
    It also links the record having been written into the join buffer with
    the matched record in the previous cache if there is any.
    The implementation assumes that the function get_curr_link() 
    will return exactly the pointer to this matched record.

  RETURN VALUE
    TRUE    if it has been decided that it should be the last record
            in the join buffer,
    FALSE   otherwise
*/

bool JOIN_CACHE::put_record()
{
  bool is_full;
  uchar *link= 0;
  if (prev_cache)
    link= prev_cache->get_curr_rec_link();
  write_record_data(link, &is_full);
  return is_full;
}
  

/* 
  Read the next record from the join buffer: the default implementation

  SYNOPSIS
    get_record()

  DESCRIPTION
    This default implementation of the virtual function get_record
    reads fields of the next record from the join buffer of this cache.
    The function also reads all other fields associated with this record
    from the the join buffers of the previous caches. The fields are read
    into the corresponding record buffers.
    It is supposed that 'pos' points to the position in the buffer 
    right after the previous record when the function is called.
    When the function returns the 'pos' values is updated to point
    to the position after the read record.
    The value of 'curr_rec_pos' is also updated by the function to
    point to the beginning of the first field of the record in the
    join buffer.    

  RETURN VALUE
    TRUE    there are no more records to read from the join buffer
    FALSE   otherwise
*/

bool JOIN_CACHE::get_record()
{ 
  bool res;
  uchar *prev_rec_ptr= 0;
  if (with_length)
    pos+= size_of_rec_len;
  if (prev_cache)
  {
    pos+= prev_cache->get_size_of_rec_offset();
    prev_rec_ptr= prev_cache->get_rec_ref(pos);
  }
  curr_rec_pos= pos;
  if (!(res= read_all_record_fields() == NO_MORE_RECORDS_IN_BUFFER))
  {
    pos+= referenced_fields*size_of_fld_ofs;
    if (prev_cache)
      prev_cache->get_record_by_pos(prev_rec_ptr);
  } 
  return res; 
}


/* 
  Read a positioned record from the join buffer: the default implementation

  SYNOPSIS
    get_record_by_pos()
      rec_ptr  position of the first field of the record in the join buffer

  DESCRIPTION
    This default implementation of the virtual function get_record_pos
    reads the fields of the record positioned at 'rec_ptr' from the join buffer.
    The function also reads all other fields associated with this record 
    from the the join buffers of the previous caches. The fields are read
    into the corresponding record buffers.

  RETURN VALUE
    none
*/

void JOIN_CACHE::get_record_by_pos(uchar *rec_ptr)
{
  uchar *save_pos= pos;
  pos= rec_ptr;
  read_all_record_fields();
  pos= save_pos;
  if (prev_cache)
  {
    uchar *prev_rec_ptr= prev_cache->get_rec_ref(rec_ptr);
    prev_cache->get_record_by_pos(prev_rec_ptr);
  }
}


/* 
  Get the match flag from the referenced record: the default implementation

  SYNOPSIS
    get_match_flag_by_pos()
      rec_ptr  position of the first field of the record in the join buffer

  DESCRIPTION
    This default implementation of the virtual function get_match_flag_by_pos
    get the match flag for the record pointed by the reference at the position
    rec_ptr. If the match flag is placed in one of the previous buffers the
    function first reaches the linked record fields in this buffer.

  RETURN VALUE
    match flag for the record at the position rec_ptr
*/

enum JOIN_CACHE::Match_flag JOIN_CACHE::get_match_flag_by_pos(uchar *rec_ptr)
{
  Match_flag match_fl= MATCH_NOT_FOUND;
  if (with_match_flag)
  {
    match_fl= (enum Match_flag) rec_ptr[0];
    return match_fl;
  }
  if (prev_cache)
  {
    uchar *prev_rec_ptr= prev_cache->get_rec_ref(rec_ptr);
    return prev_cache->get_match_flag_by_pos(prev_rec_ptr);
  } 
  DBUG_ASSERT(0);
  return match_fl;
}


/* 
  Calculate the increment of the auxiliary buffer for a record write

  SYNOPSIS
    aux_buffer_incr()
      recno   the number of the record the increment to be calculated for

  DESCRIPTION
    This function calls the aux_buffer_incr the method of the
    companion member join_tab_scan to calculate the growth of the
    auxiliary buffer when the recno-th record is added to the
    join_buffer of this cache.

  RETURN VALUE
    the number of bytes in the increment 
*/

uint JOIN_CACHE::aux_buffer_incr(ulong recno)
{ 
  return join_tab_scan->aux_buffer_incr(recno);
}

/* 
  Read all flag and data fields of a record from the join buffer

  SYNOPSIS
    read_all_record_fields()

  DESCRIPTION
    The function reads all flag and data fields of a record from the join
    buffer into the corresponding record buffers.
    The fields are read starting from the position 'pos' which is
    supposed to point to the beginning og the first record field.
    The function increments the value of 'pos' by the length of the
    read data. 

  RETURN VALUE
    (-1)   if there is no more records in the join buffer
    length of the data read from the join buffer - otherwise
*/

uint JOIN_CACHE::read_all_record_fields()
{
  uchar *init_pos= pos;
  
  if (pos > last_rec_pos || !records)
    return NO_MORE_RECORDS_IN_BUFFER;

  /* First match flag, read null bitmaps and null_row flag for each table */
  read_flag_fields();
 
  /* Now read the remaining table fields if needed */
  CACHE_FIELD *copy= field_descr+flag_fields;
  CACHE_FIELD *copy_end= field_descr+fields;
  bool blob_in_rec_buff= blob_data_is_in_rec_buff(init_pos);
  for ( ; copy < copy_end; copy++)
    read_record_field(copy, blob_in_rec_buff);

  return (uint) (pos-init_pos);
}


/* 
  Read all flag fields of a record from the join buffer

  SYNOPSIS
    read_flag_fields()

  DESCRIPTION
    The function reads all flag fields of a record from the join
    buffer into the corresponding record buffers.
    The fields are read starting from the position 'pos'.
    The function increments the value of 'pos' by the length of the
    read data. 

  RETURN VALUE
    length of the data read from the join buffer
*/

uint JOIN_CACHE::read_flag_fields()
{
  uchar *init_pos= pos;
  CACHE_FIELD *copy= field_descr;
  CACHE_FIELD *copy_end= copy+flag_fields;
  if (with_match_flag)
  {
    copy->str[0]= test((Match_flag) pos[0] == MATCH_FOUND);
    pos+= copy->length;
    copy++;    
  } 
  for ( ; copy < copy_end; copy++)
  {
    memcpy(copy->str, pos, copy->length);
    pos+= copy->length;
  }
  return (pos-init_pos);
}


/* 
  Read a data record field from the join buffer

  SYNOPSIS
    read_record_field()
      copy             the descriptor of the data field to be read
      blob_in_rec_buff indicates whether this is the field from the record
                       whose blob data are in record buffers

  DESCRIPTION
    The function reads the data field specified by the parameter copy
    from the join buffer into the corresponding record buffer. 
    The field is read starting from the position 'pos'.
    The data of blob values is not copied from the join buffer.
    The function increments the value of 'pos' by the length of the
    read data. 

  RETURN VALUE
    length of the data read from the join buffer
*/

uint JOIN_CACHE::read_record_field(CACHE_FIELD *copy, bool blob_in_rec_buff)
{
  uint len;
  /* Do not copy the field if its value is null */ 
  if (copy->field && copy->field->maybe_null() && copy->field->is_null())
    return 0;           
  if (copy->type == CACHE_BLOB)
  {
    Field_blob *blob_field= (Field_blob *) copy->field;
    /* 
      Copy the length and the pointer to data but not the blob data 
      itself to the record buffer
    */ 
    if (blob_in_rec_buff)
    {
      blob_field->set_image(pos, copy->length+sizeof(char*),
			    blob_field->charset());
      len= copy->length+sizeof(char*);
    }
    else
    {
      blob_field->set_ptr(pos, pos+copy->length);
      len= copy->length+blob_field->get_length();
    }
  }
  else
  {
    switch (copy->type) {
    case CACHE_VARSTR1:
      /* Copy the significant part of the short varstring field */
      len= (uint) pos[0] + 1;
      memcpy(copy->str, pos, len);
      break;
    case CACHE_VARSTR2:
      /* Copy the significant part of the long varstring field */
      len= uint2korr(pos) + 2;
      memcpy(copy->str, pos, len);
      break;
    case CACHE_STRIPPED:
      /* Pad the value by spaces that has been stripped off */
      len= uint2korr(pos);
      memcpy(copy->str, pos+2, len);
      memset(copy->str+len, ' ', copy->length-len);
      len+= 2;
      break;
    default:
      /* Copy the entire image of the field from the record buffer */
      len= copy->length;
      memcpy(copy->str, pos, len);
    }
  }
  pos+= len;
  return len;
}


/* 
  Read a referenced field from the join buffer

  SYNOPSIS
    read_referenced_field()
      copy         pointer to the descriptor of the referenced field
      rec_ptr      pointer to the record that may contain this field
      len  IN/OUT  total length of the record fields 

  DESCRIPTION
    The function checks whether copy points to a data field descriptor
    for this cache object. If it does not then the function returns
    FALSE. Otherwise the function reads the field of the record in
    the join buffer pointed by 'rec_ptr' into the corresponding record
    buffer and returns TRUE.
    If the value of *len is 0 then the function sets it to the total
    length of the record fields including possible trailing offset
    values. Otherwise *len is supposed to provide this value that
    has been obtained earlier. 

  NOTE
    If the value of the referenced field is null then the offset
    for the value is set to 0. If the value of a field can be null
    then the value of flag_fields is always positive. So the offset
    for any non-null value cannot be 0 in this case. 

  RETURN VALUE
    TRUE   'copy' points to a data descriptor of this join cache
    FALSE  otherwise
*/

bool JOIN_CACHE::read_referenced_field(CACHE_FIELD *copy,
                                       uchar *rec_ptr, 
                                       uint *len)
{
  uchar *ptr;
  uint offset;
  if (copy < field_descr || copy >= field_descr+fields)
    return FALSE;
  if (!*len)
  {
    /* Get the total length of the record fields */ 
    uchar *len_ptr= rec_ptr;
    if (prev_cache)
      len_ptr-= prev_cache->get_size_of_rec_offset();
    *len= get_rec_length(len_ptr-size_of_rec_len);
  }
  
  ptr= rec_ptr-(prev_cache ? prev_cache->get_size_of_rec_offset() : 0);  
  offset= get_fld_offset(ptr+ *len - 
                         size_of_fld_ofs*
                         (referenced_fields+1-copy->referenced_field_no));  
  bool is_null= FALSE;
  Field *field= copy->field;
  if (offset == 0 && flag_fields)
    is_null= TRUE;
  if (is_null)
  {
    field->set_null();
    if (!field->real_maybe_null())
      field->table->null_row= 1;
  }
  else
  {
    uchar *save_pos= pos;
    field->set_notnull(); 
    if (!field->real_maybe_null())
      field->table->null_row= 0;
    pos= rec_ptr+offset;
    read_record_field(copy, blob_data_is_in_rec_buff(rec_ptr));
    pos= save_pos;
  }
  return TRUE;
}
   

/* 
  Skip record from join buffer if's already matched: default implementation

  SYNOPSIS
    skip_if_matched()

  DESCRIPTION
    This default implementation of the virtual function skip_if_matched
    skips the next record from the join buffer if its  match flag is set to 
    MATCH_FOUND.
    If the record is skipped the value of 'pos' is set to point to the position
    right after the record.

  RETURN VALUE
    TRUE   the match flag is set to MATCH_FOUND and the record has been skipped
    FALSE  otherwise
*/

bool JOIN_CACHE::skip_if_matched()
{
  DBUG_ASSERT(with_length);
  uint offset= size_of_rec_len;
  if (prev_cache)
    offset+= prev_cache->get_size_of_rec_offset();
  /* Check whether the match flag is MATCH_FOUND */
  if (get_match_flag_by_pos(pos+offset) == MATCH_FOUND)
  {
    pos+= size_of_rec_len + get_rec_length(pos);
    return TRUE;
  }
  return FALSE;
}      


/* 
  Skip record from join buffer if the match isn't needed: default implementation

  SYNOPSIS
    skip_if_not_needed_match()

  DESCRIPTION
    This default implementation of the virtual function skip_if_not_needed_match
    skips the next record from the join buffer if its match flag is not 
    MATCH_NOT_FOUND, and, either its value is MATCH_FOUND and join_tab is the
    first inner table of an inner join, or, its value is MATCH_IMPOSSIBLE
    and join_tab is the first inner table of an outer join.
    If the record is skipped the value of 'pos' is set to point to the position
    right after the record.

  RETURN VALUE
    TRUE    the record has to be skipped
    FALSE   otherwise 
*/

bool JOIN_CACHE::skip_if_not_needed_match()
{
  DBUG_ASSERT(with_length);
  enum Match_flag match_fl;
  uint offset= size_of_rec_len;
  if (prev_cache)
    offset+= prev_cache->get_size_of_rec_offset();

  if ((match_fl= get_match_flag_by_pos(pos+offset)) != MATCH_NOT_FOUND &&
      (join_tab->check_only_first_match() == (match_fl == MATCH_FOUND)) )
  {
    pos+= size_of_rec_len + get_rec_length(pos);
    return TRUE;
  }
  return FALSE;
}      


/* 
  Restore the fields of the last record from the join buffer
 
  SYNOPSIS
    restore_last_record()

  DESCRIPTION
    This function restore the values of the fields of the last record put
    into join buffer in record buffers. The values most probably have been
    overwritten by the field values from other records when they were read
    from the join buffer into the record buffer in order to check pushdown
    predicates.

  RETURN
    none
*/

void JOIN_CACHE::restore_last_record()
{
  if (records)
    get_record_by_pos(last_rec_pos);
}


/*
  Join records from the join buffer with records from the next join table    

  SYNOPSIS
    join_records()
      skip_last    do not find matches for the last record from the buffer

  DESCRIPTION
    The functions extends all records from the join buffer by the matched
    records from join_tab. In the case of outer join operation it also
    adds null complementing extensions for the records from the join buffer
    that have no match. 
    No extensions are generated for the last record from the buffer if
    skip_last is true.  

  NOTES
    The function must make sure that if linked join buffers are used then
    a join buffer cannot be refilled again until all extensions in the
    buffers chained to this one are generated.
    Currently an outer join operation with several inner tables always uses
    at least two linked buffers with the match join flags placed in the
    first buffer. Any record composed of rows of the inner tables that
    matches a record in this buffer must refer to the position of the
    corresponding match flag.

  IMPLEMENTATION
    When generating extensions for outer tables of an outer join operation
    first we generate all extensions for those records from the join buffer
    that have matches, after which null complementing extension for all
    unmatched records from the join buffer are generated.  
      
  RETURN VALUE
    return one of enum_nested_loop_state, except NESTED_LOOP_NO_MORE_ROWS.
*/ 

enum_nested_loop_state JOIN_CACHE::join_records(bool skip_last)
{
  JOIN_TAB *tab;
  enum_nested_loop_state rc= NESTED_LOOP_OK;
  bool outer_join_first_inner= join_tab->is_first_inner_for_outer_join();

  if (outer_join_first_inner && !join_tab->first_unmatched)
    join_tab->not_null_compl= TRUE;   

  if (!join_tab->first_unmatched)
  {
    /* Find all records from join_tab that match records from join buffer */
    rc= join_matching_records(skip_last);   
    if (rc != NESTED_LOOP_OK && rc != NESTED_LOOP_NO_MORE_ROWS)
      goto finish;
    if (outer_join_first_inner)
    {
      if (next_cache)
      {
        /* 
          Ensure that all matches for outer records from join buffer are to be
          found. Now we ensure that all full records are found for records from
          join buffer. Generally this is an overkill.
          TODO: Ensure that only matches of the inner table records have to be
          found for the records from join buffer.
	*/ 
        rc= next_cache->join_records(skip_last);
        if (rc != NESTED_LOOP_OK && rc != NESTED_LOOP_NO_MORE_ROWS)
          goto finish;
      }
      join_tab->not_null_compl= FALSE;
      /* Prepare for generation of null complementing extensions */
      for (tab= join_tab->first_inner; tab <= join_tab->last_inner; tab++)
        tab->first_unmatched= join_tab->first_inner;
    }
  }
  if (join_tab->first_unmatched)
  {
    if (is_key_access())
      restore_last_record();

    /* 
      Generate all null complementing extensions for the records from
      join buffer that don't have any matching rows from the inner tables.
    */
    reset(FALSE);
    rc= join_null_complements(skip_last);   
    if (rc != NESTED_LOOP_OK && rc != NESTED_LOOP_NO_MORE_ROWS)
      goto finish;
  }
  if(next_cache)
  {
    /* 
      When using linked caches we must ensure the records in the next caches
      that refer to the records in the join buffer are fully extended.
      Otherwise we could have references to the records that have been
      already erased from the join buffer and replaced for new records. 
    */ 
    rc= next_cache->join_records(skip_last);
    if (rc != NESTED_LOOP_OK && rc != NESTED_LOOP_NO_MORE_ROWS)
      goto finish;
  }
  if (outer_join_first_inner)
  {
    /* 
      All null complemented rows have been already generated for all
      outer records from join buffer. Restore the state of the
      first_unmatched values to 0 to avoid another null complementing.
    */
    for (tab= join_tab->first_inner; tab <= join_tab->last_inner; tab++)
      tab->first_unmatched= 0;
  } 
 
  if (skip_last)
  {
    DBUG_ASSERT(!is_key_access());
    /*
       Restore the last record from the join buffer to generate
       all extentions for it.
    */
    get_record();		               
  }

finish:
  restore_last_record();
  reset(TRUE);
  return rc;
}


/*   
  Find matches from the next table for records from the join buffer 

  SYNOPSIS
    join_matching_records()
      skip_last    do not look for matches for the last partial join record 

  DESCRIPTION
    The function retrieves rows of the join_tab table and checks whether they
    match partial join records from the join buffer. If a match is found
    the function will call the sub_select function trying to look for matches
    for the remaining join operations.
    This function currently is called only from the function join_records.    
    If the value of skip_last is true the function writes the partial join
    record from the record buffer into the join buffer to save its value for
    the future processing in the caller function.

  NOTES
    If employed by BNL or BNLH join algorithms the function performs a full
    scan of join_tab for each refill of the join buffer. If BKA or BKAH
    algorithms are used then the function iterates only over those records
    from join_tab that can be accessed by keys built over records in the join
    buffer. To apply a proper method of iteration the function just calls
    virtual iterator methods (open, next, close) of the member join_tab_scan.
    The member can be either of the JOIN_TAB_SCAN or JOIN_TAB_SCAN_MMR type.
    The class JOIN_TAB_SCAN provides the iterator methods for BNL/BNLH join
    algorithms. The class JOIN_TAB_SCAN_MRR provides the iterator methods
    for BKA/BKAH join algorithms.
    When the function looks for records from the join buffer that would
    match a record from join_tab it iterates either over all records in
    the buffer or only over selected records. If BNL join operation is
    performed all records are checked for the match. If BNLH or BKAH
    algorithm is employed to join join_tab then the function looks only
    through the records with the same join key as the record from join_tab.
    With the BKA join algorithm only one record from the join buffer is checked
    for a match for any record from join_tab. To iterate over the candidates
    for a match the virtual function get_next_candidate_for_match is used,
    while the virtual function prepare_look_for_matches is called to prepare
    for such iteration proccess.     

  NOTES
    The function produces all matching extensions for the records in the 
    join buffer following the path of the employed blocked algorithm. 
    When an outer join operation is performed all unmatched records from
    the join buffer must be extended by null values. The function 
    'join_null_complements' serves this purpose.  
      
  RETURN VALUE
    return one of enum_nested_loop_state
*/ 

enum_nested_loop_state JOIN_CACHE::join_matching_records(bool skip_last)
{
  int error;
  enum_nested_loop_state rc= NESTED_LOOP_OK;
  join_tab->table->null_row= 0;
  bool check_only_first_match= join_tab->check_only_first_match();
  bool outer_join_first_inner= join_tab->is_first_inner_for_outer_join();

  /* Return at once if there are no records in the join buffer */
  if (!records)     
    return NESTED_LOOP_OK;   
 
  /* 
    When joining we read records from the join buffer back into record buffers.
    If matches for the last partial join record are found through a call to
    the sub_select function then this partial join record must be saved in the
    join buffer in order to be restored just before the sub_select call.
  */             
  if (skip_last)     
    put_record();     
 
  if (join_tab->use_quick == 2 && join_tab->select->quick)
  { 
    /* A dynamic range access was used last. Clean up after it */
    delete join_tab->select->quick;
    join_tab->select->quick= 0;
  }

  if ((rc= join_tab_execution_startup(join_tab)) < 0)
    goto finish2;

  /* Prepare to retrieve all records of the joined table */
  if ((error= join_tab_scan->open()))
  { 
    /* 
      TODO: if we get here, we will assert in net_send_statement(). Add test
      coverage and fix.
    */
    goto finish;
  }
  
  while (!(error= join_tab_scan->next()))   
  {
    if (join->thd->killed)
    {
      /* The user has aborted the execution of the query */
      join->thd->send_kill_message();
      rc= NESTED_LOOP_KILLED;
      goto finish; 
    }

    if (join_tab->keep_current_rowid)
      join_tab->table->file->position(join_tab->table->record[0]);
    
    /* Prepare to read matching candidates from the join buffer */
    if (prepare_look_for_matches(skip_last))
      continue;

    uchar *rec_ptr;
    /* Read each possible candidate from the buffer and look for matches */
    while ((rec_ptr= get_next_candidate_for_match()))
    { 
      /* 
        If only the first match is needed, and, it has been already found for
        the next record read from the join buffer, then the record is skipped.
        Also those records that must be null complemented are not considered
        as candidates for matches.
      */
      if ((!check_only_first_match && !outer_join_first_inner) ||
          !skip_next_candidate_for_match(rec_ptr))
      {
	read_next_candidate_for_match(rec_ptr);
        rc= generate_full_extensions(rec_ptr);
        if (rc != NESTED_LOOP_OK && rc != NESTED_LOOP_NO_MORE_ROWS)
	  goto finish;   
      }
    }
  }

finish: 
  if (error)                 
    rc= error < 0 ? NESTED_LOOP_NO_MORE_ROWS: NESTED_LOOP_ERROR;
finish2:    
  join_tab_scan->close();
  return rc;
}


/*
  Set match flag for a record in join buffer if it has not been set yet    

  SYNOPSIS
    set_match_flag_if_none()
      first_inner     the join table to which this flag is attached to
      rec_ptr         pointer to the record in the join buffer 

  DESCRIPTION
    If the records of the table are accumulated in a join buffer the function
    sets the match flag for the record in the buffer that is referred to by
    the record from this cache positioned at 'rec_ptr'. 
    The function also sets the match flag 'found' of the table first inner
    if it has not been set before. 

  NOTES
    The function assumes that the match flag for any record in any cache
    is placed in the first byte occupied by the record fields. 

  RETURN VALUE
    TRUE   the match flag is set by this call for the first time
    FALSE  the match flag has been set before this call
*/ 

bool JOIN_CACHE::set_match_flag_if_none(JOIN_TAB *first_inner,
                                        uchar *rec_ptr)
{
  if (!first_inner->cache)
  {
    /* 
      Records of the first inner table to which the flag is attached to
      are not accumulated in a join buffer.
    */
    if (first_inner->found)
      return FALSE;
    else
    {
      first_inner->found= 1;
      return TRUE;
    }
  }
  JOIN_CACHE *cache= this;
  while (cache->join_tab != first_inner)
  {
    cache= cache->prev_cache;
    DBUG_ASSERT(cache);
    rec_ptr= cache->get_rec_ref(rec_ptr);
  } 
  if ((Match_flag) rec_ptr[0] != MATCH_FOUND)
  {
    rec_ptr[0]= MATCH_FOUND;
    first_inner->found= 1;
    return TRUE;  
  }
  return FALSE;
}


/*
  Generate all full extensions for a partial join record in the buffer    

  SYNOPSIS
    generate_full_extensions()
      rec_ptr     pointer to the record from join buffer to generate extensions 

  DESCRIPTION
    The function first checks whether the current record of 'join_tab' matches
    the partial join record from join buffer located at 'rec_ptr'. If it is the
    case the function calls the join_tab->next_select method to generate
    all full extension for this partial join match.
      
  RETURN VALUE
    return one of enum_nested_loop_state.
*/ 

enum_nested_loop_state JOIN_CACHE::generate_full_extensions(uchar *rec_ptr)
{
  enum_nested_loop_state rc= NESTED_LOOP_OK;
  
  /*
    Check whether the extended partial join record meets
    the pushdown conditions. 
  */
  if (check_match(rec_ptr))
  {    
    int res= 0;

    if (!join_tab->check_weed_out_table || 
        !(res= do_sj_dups_weedout(join->thd, join_tab->check_weed_out_table)))
    {
      set_curr_rec_link(rec_ptr);
      rc= (join_tab->next_select)(join, join_tab+1, 0);
      if (rc != NESTED_LOOP_OK && rc != NESTED_LOOP_NO_MORE_ROWS)
      {
        reset(TRUE);
        return rc;
      }
    }
    if (res == -1)
    {
      rc= NESTED_LOOP_ERROR;
      return rc;
    }
  }
  return rc;
}


/*
  Check matching to a partial join record from the join buffer    

  SYNOPSIS
    check_match()
      rec_ptr     pointer to the record from join buffer to check matching to 

  DESCRIPTION
    The function checks whether the current record of 'join_tab' matches
    the partial join record from join buffer located at 'rec_ptr'. If this is
    the case and 'join_tab' is the last inner table of a semi-join or an outer
    join the function turns on the match flag for the 'rec_ptr' record unless
    it has been already set.

  NOTES
    Setting the match flag on can trigger re-evaluation of pushdown conditions
    for the record when join_tab is the last inner table of an outer join.
      
  RETURN VALUE
    TRUE   there is a match
    FALSE  there is no match
*/ 

inline bool JOIN_CACHE::check_match(uchar *rec_ptr)
{
  /* Check whether pushdown conditions are satisfied */
  if (join_tab->select && join_tab->select->skip_record(join->thd) <= 0)
    return FALSE;

  if (!join_tab->is_last_inner_table())
    return TRUE;

  /* 
     This is the last inner table of an outer join,
     and maybe of other embedding outer joins, or
     this is the last inner table of a semi-join.
  */
  JOIN_TAB *first_inner= join_tab->get_first_inner_table();
  do
  {
    set_match_flag_if_none(first_inner, rec_ptr);
    if (first_inner->check_only_first_match() &&
        !join_tab->first_inner)
      return TRUE;
    /* 
      This is the first match for the outer table row.
      The function set_match_flag_if_none has turned the flag
      first_inner->found on. The pushdown predicates for
      inner tables must be re-evaluated with this flag on.
      Note that, if first_inner is the first inner table 
      of a semi-join, but is not an inner table of an outer join
      such that 'not exists' optimization can  be applied to it, 
      the re-evaluation of the pushdown predicates is not needed.
    */      
    for (JOIN_TAB *tab= first_inner; tab <= join_tab; tab++)
    {
      if (tab->select && tab->select->skip_record(join->thd) <= 0)
        return FALSE;
    }
  }
  while ((first_inner= first_inner->first_upper) &&
         first_inner->last_inner == join_tab);
  
  return TRUE;
} 


/*
  Add null complements for unmatched outer records from join buffer    

  SYNOPSIS
    join_null_complements()
      skip_last    do not add null complements for the last record 

  DESCRIPTION
    This function is called only for inner tables of outer joins.
    The function retrieves all rows from the join buffer and adds null
    complements for those of them that do not have matches for outer
    table records.
    If the 'join_tab' is the last inner table of the embedding outer 
    join and the null complemented record satisfies the outer join
    condition then the the corresponding match flag is turned on
    unless it has been set earlier. This setting may trigger
    re-evaluation of pushdown conditions for the record. 

  NOTES
    The same implementation of the virtual method join_null_complements
    is used for BNL/BNLH/BKA/BKA join algorthm.
      
  RETURN VALUE
    return one of enum_nested_loop_state.
*/ 

enum_nested_loop_state JOIN_CACHE::join_null_complements(bool skip_last)
{
  ulonglong cnt; 
  enum_nested_loop_state rc= NESTED_LOOP_OK;
  bool is_first_inner= join_tab == join_tab->first_unmatched;
 
  /* Return at once if there are no records in the join buffer */
  if (!records)
    return NESTED_LOOP_OK;
  
  cnt= records - (is_key_access() ? 0 : test(skip_last));

  /* This function may be called only for inner tables of outer joins */ 
  DBUG_ASSERT(join_tab->first_inner);

  for ( ; cnt; cnt--)
  {
    if (join->thd->killed)
    {
      /* The user has aborted the execution of the query */
      join->thd->send_kill_message();
      rc= NESTED_LOOP_KILLED;
      goto finish;
    }
    /* Just skip the whole record if a match for it has been already found */
    if (!is_first_inner || !skip_if_matched())
    {
      get_record();
      /* The outer row is complemented by nulls for each inner table */
      restore_record(join_tab->table, s->default_values);
      mark_as_null_row(join_tab->table);  
      rc= generate_full_extensions(get_curr_rec());
      if (rc != NESTED_LOOP_OK && rc != NESTED_LOOP_NO_MORE_ROWS)
        goto finish;
    }
  }

finish:
  return rc;
}


/*
  Add a comment on the join algorithm employed by the join cache 

  SYNOPSIS
    print_explain_comment()
      str  string to add the comment on the employed join algorithm to

  DESCRIPTION
    This function adds info on the type of the used join buffer (flat or
    incremental) and on the type of the the employed join algorithm (BNL,
    BNLH, BKA or BKAH) to the the end of the sring str.

  RETURN VALUE
    none
*/ 

void JOIN_CACHE::print_explain_comment(String *str)
{
  str->append(STRING_WITH_LEN(" ("));
  const char *buffer_type= prev_cache ? "incremental" : "flat";
  str->append(buffer_type);
  str->append(STRING_WITH_LEN(", "));
  
  const char *join_alg="";
  switch (get_join_alg()) {
  case BNL_JOIN_ALG:
    join_alg= "BNL";
    break;
  case BNLH_JOIN_ALG:
    join_alg= "BNLH";
    break;
  case BKA_JOIN_ALG:
    join_alg= "BKA";
    break;
  case BKAH_JOIN_ALG:
    join_alg= "BKAH";
    break;
  default:
    DBUG_ASSERT(0);
  }

  str->append(join_alg);
  str->append(STRING_WITH_LEN(" join"));
  str->append(STRING_WITH_LEN(")"));
}


static void add_mrr_explain_info(String *str, uint mrr_mode, handler *file)
{
  char mrr_str_buf[128]={0};
  int len;
  len= file->multi_range_read_explain_info(mrr_mode, mrr_str_buf,
                                           sizeof(mrr_str_buf));
  if (len > 0)
  {
    str->append(STRING_WITH_LEN("; "));
    str->append(mrr_str_buf, len);
  }
}


void JOIN_CACHE_BKA::print_explain_comment(String *str)
{
  JOIN_CACHE::print_explain_comment(str); 
  add_mrr_explain_info(str, mrr_mode, join_tab->table->file);
}


void JOIN_CACHE_BKAH::print_explain_comment(String *str)
{
  JOIN_CACHE::print_explain_comment(str); 
  add_mrr_explain_info(str, mrr_mode, join_tab->table->file);
}


/* 
  Initialize a hashed join cache       

  SYNOPSIS
    init()

  DESCRIPTION
    The function initializes the cache structure with a hash table in it.
    The hash table will be used to store key values for the records from
    the join buffer.
    The function allocates memory for the join buffer and for descriptors of
    the record fields stored in the buffer.
    The function also initializes a hash table for record keys within the join
    buffer space.

  NOTES VALUE
    The function is supposed to be called by the init methods of the classes 
    derived from JOIN_CACHE_HASHED.
  
  RETURN VALUE
    0   initialization with buffer allocations has been succeeded
    1   otherwise
*/

int JOIN_CACHE_HASHED::init()
{
  int rc= 0;
  TABLE_REF *ref= &join_tab->ref;

  DBUG_ENTER("JOIN_CACHE_HASHED::init");

  hash_table= 0;
  key_entries= 0;

  key_length= ref->key_length;

  if ((rc= JOIN_CACHE::init()))
    DBUG_RETURN (rc);

  if (!(key_buff= (uchar*) sql_alloc(key_length)))
    DBUG_RETURN(1);

  /* Take into account a reference to the next record in the key chain */
  pack_length+= get_size_of_rec_offset(); 
  pack_length_with_blob_ptrs+= get_size_of_rec_offset();

  ref_key_info= join_tab->get_keyinfo_by_key_no(join_tab->ref.key);
  ref_used_key_parts= join_tab->ref.key_parts;

  hash_func= &JOIN_CACHE_HASHED::get_hash_idx_simple;
  hash_cmp_func= &JOIN_CACHE_HASHED::equal_keys_simple;

  KEY_PART_INFO *key_part= ref_key_info->key_part;
  KEY_PART_INFO *key_part_end= key_part+ref_used_key_parts;
  for ( ; key_part < key_part_end; key_part++)
  {
    if (!key_part->field->eq_cmp_as_binary())
    {
      hash_func= &JOIN_CACHE_HASHED::get_hash_idx_complex;
      hash_cmp_func= &JOIN_CACHE_HASHED::equal_keys_complex;
      break;
    }
  }
      
  init_hash_table();

  rec_fields_offset= get_size_of_rec_offset()+get_size_of_rec_length()+
                     (prev_cache ? prev_cache->get_size_of_rec_offset() : 0);

  data_fields_offset= 0;
  if (use_emb_key)
  {
    CACHE_FIELD *copy= field_descr;
    CACHE_FIELD *copy_end= copy+flag_fields;
    for ( ; copy < copy_end; copy++)
      data_fields_offset+= copy->length;
  } 

  DBUG_RETURN(rc);
}


/* 
  Initialize the hash table of a hashed join cache 

  SYNOPSIS
    init_hash_table()

  DESCRIPTION
    The function estimates the number of hash table entries in the hash
    table to be used and initializes this hash table within the join buffer
    space.

  RETURN VALUE
    Currently the function always returns 0;
*/

int JOIN_CACHE_HASHED::init_hash_table()
{
  hash_table= 0;
  key_entries= 0;

  /* Calculate the minimal possible value of size_of_key_ofs greater than 1 */
  uint max_size_of_key_ofs= max(2, get_size_of_rec_offset());  
  for (size_of_key_ofs= 2;
       size_of_key_ofs <= max_size_of_key_ofs;
       size_of_key_ofs+= 2)
  {    
    key_entry_length= get_size_of_rec_offset() + // key chain header
                      size_of_key_ofs +          // reference to the next key 
                      (use_emb_key ?  get_size_of_rec_offset() : key_length);

    ulong space_per_rec= avg_record_length +
                         avg_aux_buffer_incr +
                         key_entry_length+size_of_key_ofs;
    uint n= buff_size / space_per_rec;

    /*
      TODO: Make a better estimate for this upper bound of
            the number of records in in the join buffer.
    */
    uint max_n= buff_size / (pack_length-length+
                             key_entry_length+size_of_key_ofs);

    hash_entries= (uint) (n / 0.7);
    set_if_bigger(hash_entries, 1);
    
    if (offset_size(max_n*key_entry_length) <=
        size_of_key_ofs)
      break;
  }
   
  /* Initialize the hash table */ 
  hash_table= buff + (buff_size-hash_entries*size_of_key_ofs);
  cleanup_hash_table();
  curr_key_entry= hash_table;

  return 0;
}


/*
  Reallocate the join buffer of a hashed join cache
 
  SYNOPSIS
    realloc_buffer()

  DESCRITION
    The function reallocates the join buffer of the hashed join cache.
    After this it initializes a hash table within the buffer space and
    resets the join cache for writing.

  NOTES
    The function assumes that buff_size contains the new value for the join
    buffer size.  

  RETURN VALUE
    0   if the buffer has been successfully reallocated
    1   otherwise
*/

int JOIN_CACHE_HASHED::realloc_buffer()
{
  int rc;
  free();
  rc= test(!(buff= (uchar*) my_malloc(buff_size, MYF(0))));
  init_hash_table();
  reset(TRUE);
  return rc;   	
}


/*
  Get maximum size of the additional space per record used for record keys

  SYNOPSYS
    get_max_key_addon_space_per_record()
  
  DESCRIPTION
    The function returns the size of the space occupied by one key entry
    and one hash table entry.

  RETURN VALUE
    maximum size of the additional space per record that is used to store
    record keys in the hash table
*/

uint JOIN_CACHE_HASHED::get_max_key_addon_space_per_record()
{
  ulong len;
  TABLE_REF *ref= &join_tab->ref;
  /* 
    The total number of hash entries in the hash tables is bounded by
    ceiling(N/0.7) where N is the maximum number of records in the buffer.
    That's why the multiplier 2 is used in the formula below. 
  */ 
  len= (use_emb_key ?  get_size_of_rec_offset() : ref->key_length) +
        size_of_rec_ofs +    // size of the key chain header
        size_of_rec_ofs +    // >= size of the reference to the next key 
        2*size_of_rec_ofs;   // >= 2*( size of hash table entry)
  return len; 
}    


/* 
  Reset the buffer of a hashed join cache for reading/writing

  SYNOPSIS
    reset()
      for_writing  if it's TRUE the function reset the buffer for writing

  DESCRIPTION
    This implementation of the virtual function reset() resets the join buffer
    of the JOIN_CACHE_HASHED class for reading or writing.
    Additionally to what the default implementation does this function
    cleans up the hash table allocated within the buffer.  
    
  RETURN VALUE
    none
*/
 
void JOIN_CACHE_HASHED::reset(bool for_writing)
{
  this->JOIN_CACHE::reset(for_writing);
  if (for_writing && hash_table)
    cleanup_hash_table();
  curr_key_entry= hash_table;
}


/* 
  Add a record into the buffer of a hashed join cache

  SYNOPSIS
    put_record()

  DESCRIPTION
    This implementation of the virtual function put_record writes the next
    matching record into the join buffer of the JOIN_CACHE_HASHED class.
    Additionally to what the default implementation does this function
    performs the following. 
    It extracts from the record the key value used in lookups for matching
    records and searches for this key in the hash tables from the join cache.
    If it finds the key in the hash table it joins the record to the chain
    of records with this key. If the key is not found in the hash table the
    key is placed into it and a chain containing only the newly added record 
    is attached to the key entry. The key value is either placed in the hash 
    element added for the key or, if the use_emb_key flag is set, remains in
    the record from the partial join.
    If the match flag field of a record contains MATCH_IMPOSSIBLE the key is
    not created for this record. 
    
  RETURN VALUE
    TRUE    if it has been decided that it should be the last record
            in the join buffer,
    FALSE   otherwise
*/

bool JOIN_CACHE_HASHED::put_record()
{
  bool is_full;
  uchar *key;
  uint key_len= key_length;
  uchar *key_ref_ptr;
  uchar *link= 0;
  TABLE_REF *ref= &join_tab->ref;
  uchar *next_ref_ptr= pos;

  pos+= get_size_of_rec_offset();
  /* Write the record into the join buffer */  
  if (prev_cache)
    link= prev_cache->get_curr_rec_link();
  write_record_data(link, &is_full);

  if (last_written_is_null_compl)
    return is_full;    

  if (use_emb_key)
    key= get_curr_emb_key();
  else
  {
    /* Build the key over the fields read into the record buffers */ 
    cp_buffer_from_ref(join->thd, join_tab->table, ref);
    key= ref->key_buff;
  }

  /* Look for the key in the hash table */
  if (key_search(key, key_len, &key_ref_ptr))
  {
    uchar *last_next_ref_ptr;
    /* 
      The key is found in the hash table. 
      Add the record to the circular list of the records attached to this key.
      Below 'rec' is the record to be added into the record chain for the found
      key, 'key_ref' points to a flatten representation of the st_key_entry 
      structure that contains the key and the head of the record chain.
    */
    last_next_ref_ptr= get_next_rec_ref(key_ref_ptr+get_size_of_key_offset());
    /* rec->next_rec= key_entry->last_rec->next_rec */
    memcpy(next_ref_ptr, last_next_ref_ptr, get_size_of_rec_offset());
    /* key_entry->last_rec->next_rec= rec */ 
    store_next_rec_ref(last_next_ref_ptr, next_ref_ptr);
    /* key_entry->last_rec= rec */
    store_next_rec_ref(key_ref_ptr+get_size_of_key_offset(), next_ref_ptr);
  }
  else
  {
    /* 
      The key is not found in the hash table.
      Put the key into the join buffer linking it with the keys for the
      corresponding hash entry. Create a circular list with one element
      referencing the record and attach the list to the key in the buffer.
    */
    uchar *cp= last_key_entry;
    cp-= get_size_of_rec_offset()+get_size_of_key_offset();
    store_next_key_ref(key_ref_ptr, cp);
    store_null_key_ref(cp);
    store_next_rec_ref(next_ref_ptr, next_ref_ptr);
    store_next_rec_ref(cp+get_size_of_key_offset(), next_ref_ptr);
    if (use_emb_key)
    {
      cp-= get_size_of_rec_offset();
      store_emb_key_ref(cp, key);
    }
    else
    {
      cp-= key_len;
      memcpy(cp, key, key_len);
    }
    last_key_entry= cp;
    DBUG_ASSERT(last_key_entry >= end_pos);
    /* Increment the counter of key_entries in the hash table */ 
    key_entries++;
  }  
  return is_full;
}


/*
  Read the next record from the buffer of a hashed join cache

  SYNOPSIS
    get_record()

  DESCRIPTION
    Additionally to what the default implementation of the virtual 
    function get_record does this implementation skips the link element
    used to connect the records with the same key into a chain. 

  RETURN VALUE
    TRUE    there are no more records to read from the join buffer
    FALSE   otherwise
*/

bool JOIN_CACHE_HASHED::get_record()
{ 
  pos+= get_size_of_rec_offset();
  return this->JOIN_CACHE::get_record();
}


/* 
  Skip record from a hashed join buffer if its match flag is set to MATCH_FOUND

  SYNOPSIS
    skip_if_matched()

  DESCRIPTION
    This implementation of the virtual function skip_if_matched does
    the same as the default implementation does, but it takes into account
    the link element used to connect the records with the same key into a chain. 

  RETURN VALUE
    TRUE    the match flag is MATCH_FOUND  and the record has been skipped
    FALSE   otherwise 
*/

bool JOIN_CACHE_HASHED::skip_if_matched()
{
  uchar *save_pos= pos;
  pos+= get_size_of_rec_offset();
  if (!this->JOIN_CACHE::skip_if_matched())
  {
    pos= save_pos;
    return FALSE;
  }
  return TRUE;
}


/* 
  Skip record from a hashed join buffer if its match flag dictates to do so

  SYNOPSIS
    skip_if_uneeded_match()

  DESCRIPTION
    This implementation of the virtual function skip_if_not_needed_match does
    the same as the default implementation does, but it takes into account
    the link element used to connect the records with the same key into a chain. 

  RETURN VALUE
    TRUE    the match flag dictates to skip the record
    FALSE   the match flag is off 
*/

bool JOIN_CACHE_HASHED::skip_if_not_needed_match()
{
  uchar *save_pos= pos;
  pos+= get_size_of_rec_offset();
  if (!this->JOIN_CACHE::skip_if_not_needed_match())
  {
    pos= save_pos;
    return FALSE;
  }
  return TRUE;
}


/* 
  Search for a key in the hash table of the join buffer

  SYNOPSIS
    key_search()
      key             pointer to the key value
      key_len         key value length
      key_ref_ptr OUT position of the reference to the next key from 
                      the hash element for the found key , or
                      a position where the reference to the the hash 
                      element for the key is to be added in the
                      case when the key has not been found
      
  DESCRIPTION
    The function looks for a key in the hash table of the join buffer.
    If the key is found the functionreturns the position of the reference
    to the next key from  to the hash element for the given key. 
    Otherwise the function returns the position where the reference to the
    newly created hash element for the given key is to be added.  

  RETURN VALUE
    TRUE    the key is found in the hash table
    FALSE   otherwise
*/

bool JOIN_CACHE_HASHED::key_search(uchar *key, uint key_len,
                                   uchar **key_ref_ptr) 
{
  bool is_found= FALSE;
  uint idx= (this->*hash_func)(key, key_length);
  uchar *ref_ptr= hash_table+size_of_key_ofs*idx;
  while (!is_null_key_ref(ref_ptr))
  {
    uchar *next_key;
    ref_ptr= get_next_key_ref(ref_ptr);
    next_key= use_emb_key ? get_emb_key(ref_ptr-get_size_of_rec_offset()) :
                            ref_ptr-key_length;

    if ((this->*hash_cmp_func)(next_key, key, key_len))
    {
      is_found= TRUE;
      break;
    }
  }
  *key_ref_ptr= ref_ptr;
  return is_found;
} 


/* 
  Hash function that considers a key in the hash table as byte array

  SYNOPSIS
    get_hash_idx_simple()
      key             pointer to the key value
      key_len         key value length
      
  DESCRIPTION
    The function calculates an index of the hash entry in the hash table
    of the join buffer for the given key. It considers the key just as
    a sequence of bytes of the length key_len.

  RETURN VALUE
    the calculated index of the hash entry for the given key  
*/

inline
uint JOIN_CACHE_HASHED::get_hash_idx_simple(uchar* key, uint key_len)
{
  ulong nr= 1;
  ulong nr2= 4;
  uchar *pos= key;
  uchar *end= key+key_len;
  for (; pos < end ; pos++)
  {
    nr^= (ulong) ((((uint) nr & 63)+nr2)*((uint) *pos))+ (nr << 8);
    nr2+= 3;
  }
  return nr % hash_entries;
}


/* 
  Hash function that takes into account collations of the components of the key  

  SYNOPSIS
    get_hash_idx_complex()
      key             pointer to the key value
      key_len         key value length
      
  DESCRIPTION
    The function calculates an index of the hash entry in the hash table
    of the join buffer for the given key. It takes into account that the
    components of the key may be of a varchar type with different collations.
    The function guarantees that the same hash value for any two equal
    keys that may differ as byte sequences.
    The function takes the info about the components of the key, their
    types and used collations from the class member ref_key_info containing
    a pointer to the descriptor of the index that can be used for the join
    operation.

  RETURN VALUE
    the calculated index of the hash entry for the given key  
*/

inline
uint JOIN_CACHE_HASHED::get_hash_idx_complex(uchar *key, uint key_len)
{
  return 
    (uint) (key_hashnr(ref_key_info, ref_used_key_parts, key) % hash_entries);
}


/* 
  Compare two key entries in the hash table as sequence of bytes

  SYNOPSIS
    equal_keys_simple()
      key1            pointer to the first key entry
      key2            pointer to the second key entry 
      key_len         the length of the key values
      
  DESCRIPTION
    The function compares two key entries in the hash table key1 and key2
    as two sequences bytes of the length key_len

  RETURN VALUE
    TRUE       key1 coincides with key2
    FALSE      otherwise
*/

inline
bool JOIN_CACHE_HASHED::equal_keys_simple(uchar *key1, uchar *key2,
                                          uint key_len)
{
  return memcmp(key1, key2, key_len) == 0;
}


/* 
  Compare two key entries taking into account the used collation

  SYNOPSIS
    equal_keys_complex()
      key1            pointer to the first key entry
      key2            pointer to the second key entry 
      key_len         the length of the key values
      
  DESCRIPTION
    The function checks whether two key entries in the hash table
    key1 and key2 are equal as, possibly, compound keys of a certain
    structure whose components may be of a varchar type and may
    employ different collations.
    The descriptor of the key structure is taken from the class
    member ref_key_info.

  RETURN VALUE
    TRUE       key1 is equal tokey2
    FALSE      otherwise
*/

inline
bool JOIN_CACHE_HASHED::equal_keys_complex(uchar *key1, uchar *key2,
                                          uint key_len)
{
  return key_buf_cmp(ref_key_info, ref_used_key_parts, key1, key2) == 0;
}


/* 
  Clean up the hash table of the join buffer

  SYNOPSIS
    cleanup_hash_table()
      key             pointer to the key value
      key_len         key value length
      
  DESCRIPTION
    The function cleans up the hash table in the join buffer removing all
    hash elements from the table. 

  RETURN VALUE
    none  
*/

void JOIN_CACHE_HASHED:: cleanup_hash_table()
{
  last_key_entry= hash_table;
  bzero(hash_table, (buff+buff_size)-hash_table);
  key_entries= 0;
}


/*
  Check whether all records in a key chain have their match flags set on   

  SYNOPSIS
    check_all_match_flags_for_key()
      key_chain_ptr     

  DESCRIPTION
    This function retrieves records in the given circular chain and checks
    whether their match flags are set on. The parameter key_chain_ptr shall
    point to the position in the join buffer storing the reference to the
    last element of this chain. 
            
  RETURN VALUE
    TRUE   if each retrieved record has its match flag set to MATCH_FOUND
    FALSE  otherwise 
*/

bool JOIN_CACHE_HASHED::check_all_match_flags_for_key(uchar *key_chain_ptr)
{
  uchar *last_rec_ref_ptr= get_next_rec_ref(key_chain_ptr);
  uchar *next_rec_ref_ptr= last_rec_ref_ptr;
  do
  {
    next_rec_ref_ptr= get_next_rec_ref(next_rec_ref_ptr);
    uchar *rec_ptr= next_rec_ref_ptr+rec_fields_offset;
    if (get_match_flag_by_pos(rec_ptr) != MATCH_FOUND)
      return FALSE;
  }
  while (next_rec_ref_ptr != last_rec_ref_ptr);
  return TRUE;
}
  

/* 
  Get the next key built for the records from the buffer of a hashed join cache

  SYNOPSIS
    get_next_key()
      key    pointer to the buffer where the key value is to be placed

  DESCRIPTION
    The function reads the next key value stored in the hash table of the
    join buffer. Depending on the value of the use_emb_key flag of the
    join cache the value is read either from the table itself or from
    the record field where it occurs. 

  RETURN VALUE
    length of the key value - if the starting value of 'cur_key_entry' refers
    to the position after that referred by the the value of 'last_key_entry',    
    0 - otherwise.     
*/

uint JOIN_CACHE_HASHED::get_next_key(uchar ** key)
{  
  if (curr_key_entry == last_key_entry)
    return 0;

  curr_key_entry-= key_entry_length;

  *key = use_emb_key ? get_emb_key(curr_key_entry) : curr_key_entry;

  DBUG_ASSERT(*key >= buff && *key < hash_table);

  return key_length;
}


/* 
  Initiate an iteration process over records in the joined table

  SYNOPSIS
    open()

  DESCRIPTION
    The function initiates the process of iteration over records from the 
    joined table recurrently performed by the BNL/BKLH join algorithm.  

  RETURN VALUE   
    0            the initiation is a success 
    error code   otherwise     
*/

int JOIN_TAB_SCAN::open()
{
  save_or_restore_used_tabs(join_tab, FALSE);
  is_first_record= TRUE;
  return join_init_read_record(join_tab);
}


/* 
  Read the next record that can match while scanning the joined table

  SYNOPSIS
    next()

  DESCRIPTION
    The function reads the next record from the joined table that can
    match some records in the buffer of the join cache 'cache'. To do
    this the function calls the function that scans table records and
    looks for the next one that meets the condition pushed to the
    joined table join_tab.

  NOTES
    The function catches the signal that kills the query.

  RETURN VALUE   
    0            the next record exists and has been successfully read 
    error code   otherwise     
*/

int JOIN_TAB_SCAN::next()
{
  int err= 0;
  int skip_rc;
  READ_RECORD *info= &join_tab->read_record;
  SQL_SELECT *select= join_tab->cache_select;
  if (is_first_record)
    is_first_record= FALSE;
  else
    err= info->read_record(info);
  if (!err)
    update_virtual_fields(join->thd, join_tab->table);
  while (!err && select && (skip_rc= select->skip_record(join->thd)) <= 0)
  {
    if (join->thd->killed || skip_rc < 0) 
      return 1;
    /* 
      Move to the next record if the last retrieved record does not
      meet the condition pushed to the table join_tab.
    */
    err= info->read_record(info);
    if (!err)
      update_virtual_fields(join->thd, join_tab->table);
  } 
  return err; 
}


/*
  Walk back in join order from join_tab until we encounter a join tab with
  tab->cache!=NULL, and save/restore tab->table->status along the way.

  @param save TRUE   save 
              FALSE  restore
*/

static void save_or_restore_used_tabs(JOIN_TAB *join_tab, bool save)
{
  JOIN_TAB *first= join_tab->bush_root_tab?
                     join_tab->bush_root_tab->bush_children->start :
                     join_tab->join->join_tab + join_tab->join->const_tables;

  for (JOIN_TAB *tab= join_tab-1; tab != first && !tab->cache; tab--)
  {
    if (tab->bush_children)
    {
      for (JOIN_TAB *child= tab->bush_children->start;
           child != tab->bush_children->end;
           child++)
      {
        if (save)
          child->table->status= child->status;
        else
        {
          tab->status= tab->table->status;
          tab->table->status= 0;
        }
      }
    }

    if (save)
      tab->table->status= tab->status;
    else
    {
      tab->status= tab->table->status;
      tab->table->status= 0;
    }
  }
}


/* 
  Perform finalizing actions for a scan over the table records

  SYNOPSIS
    close()

  DESCRIPTION
    The function performs the necessary restoring actions after
    the table scan over the joined table has been finished.

  RETURN VALUE   
    none      
*/

void JOIN_TAB_SCAN::close()
{
  save_or_restore_used_tabs(join_tab, TRUE);
}


/*
  Prepare to iterate over the BNL join cache buffer to look for matches 

  SYNOPSIS
    prepare_look_for_matches()
      skip_last   <-> ignore the last record in the buffer

  DESCRIPTION
    The function prepares the join cache for an iteration over the
    records in the join buffer. The iteration is performed when looking
    for matches for the record from the joined table join_tab that 
    has been placed into the record buffer of the joined table.
    If the value of the parameter skip_last is TRUE then the last
    record from the join buffer is ignored.
    The function initializes the counter of the records that have been
    not iterated over yet.
    
  RETURN VALUE   
    TRUE    there are no records in the buffer to iterate over 
    FALSE   otherwise
*/
    
bool JOIN_CACHE_BNL::prepare_look_for_matches(bool skip_last)
{
  if (!records)
    return TRUE;
  reset(FALSE);
  rem_records= records-test(skip_last);
  return rem_records == 0;
}


/*
  Get next record from the BNL join cache buffer when looking for matches 

  SYNOPSIS
    get_next_candidate_for_match

  DESCRIPTION
    This method is used for iterations over the records from the join
    cache buffer when looking for matches for records from join_tab.
    The methods performs the necessary preparations to read the next record
    from the join buffer into the record buffer by the method
    read_next_candidate_for_match, or, to skip the next record from the join 
    buffer by the method skip_recurrent_candidate_for_match.    
    This implementation of the virtual method get_next_candidate_for_match
    just  decrements the counter of the records that are to be iterated over
    and returns the current value of the cursor 'pos' as the position of 
    the record to be processed. 
    
  RETURN VALUE    
    pointer to the position right after the prefix of the current record
    in the join buffer if the there is another record to iterate over,
    0 - otherwise.  
*/

uchar *JOIN_CACHE_BNL::get_next_candidate_for_match()
{
  if (!rem_records)
    return 0;
  rem_records--;
  return pos+base_prefix_length;
} 


/*
  Check whether the matching record from the BNL cache is to be skipped 

  SYNOPSIS
    skip_next_candidate_for_match
    rec_ptr  pointer to the position in the join buffer right after the prefix 
             of the current record

  DESCRIPTION
    This implementation of the virtual function just calls the
    method skip_if_not_needed_match to check whether the record referenced by
    ref_ptr has its match flag set either to MATCH_FOUND and join_tab is the
    first inner table of a semi-join, or it's set to MATCH_IMPOSSIBLE and
    join_tab is the first inner table of an outer join.
    If so, the function just skips this record setting the value of the
    cursor 'pos' to the position right after it.

  RETURN VALUE    
    TRUE   the record referenced by rec_ptr has been skipped
    FALSE  otherwise  
*/

bool JOIN_CACHE_BNL::skip_next_candidate_for_match(uchar *rec_ptr)
{
  pos= rec_ptr-base_prefix_length; 
  return skip_if_not_needed_match();
}


/*
  Read next record from the BNL join cache buffer when looking for matches 

  SYNOPSIS
    read_next_candidate_for_match
    rec_ptr  pointer to the position in the join buffer right after the prefix
             the current record.

  DESCRIPTION
    This implementation of the virtual method read_next_candidate_for_match
    calls the method get_record to read the record referenced by rec_ptr from
    the join buffer into the record buffer. If this record refers to the
    fields in the other join buffers the call of get_record ensures that
    these fields are read into the corresponding record buffers as well.
    This function is supposed to be called after a successful call of
    the method get_next_candidate_for_match.
    
  RETURN VALUE   
    none
*/

void JOIN_CACHE_BNL::read_next_candidate_for_match(uchar *rec_ptr)
{
  pos= rec_ptr-base_prefix_length;
  get_record();
} 


/*
  Initialize the BNL join cache 

  SYNOPSIS
    init

  DESCRIPTION
    The function initializes the cache structure. It is supposed to be called
    right after a constructor for the JOIN_CACHE_BNL.

  NOTES
    The function first constructs a companion object of the type JOIN_TAB_SCAN,
    then it calls the init method of the parent class.
    
  RETURN VALUE  
    0   initialization with buffer allocations has been succeeded
    1   otherwise
*/

int JOIN_CACHE_BNL::init()
{
  DBUG_ENTER("JOIN_CACHE_BNL::init");

  if (!(join_tab_scan= new JOIN_TAB_SCAN(join, join_tab)))
    DBUG_RETURN(1);

  DBUG_RETURN(JOIN_CACHE::init());
}


/*
  Get the chain of records from buffer matching the current candidate for join

  SYNOPSIS
    get_matching_chain_by_join_key()

  DESCRIPTION
    This function first build a join key for the record of join_tab that
    currently is in the join buffer for this table. Then it looks for
    the key entry with this key in the hash table of the join cache.
    If such a key entry is found the function returns the pointer to
    the head of the chain of records in the join_buffer that match this
    key.

  RETURN VALUE
    The pointer to the corresponding circular list of records if
    the key entry with the join key is found, 0 - otherwise.
*/  

uchar *JOIN_CACHE_BNLH::get_matching_chain_by_join_key()
{
  uchar *key_ref_ptr;
  TABLE *table= join_tab->table;
  TABLE_REF *ref= &join_tab->ref;
  KEY *keyinfo= join_tab->get_keyinfo_by_key_no(ref->key);
  /* Build the join key value out of the record in the record buffer */
  key_copy(key_buff, table->record[0], keyinfo, key_length, TRUE);
  /* Look for this key in the join buffer */
  if (!key_search(key_buff, key_length, &key_ref_ptr))
    return 0;
  return key_ref_ptr+get_size_of_key_offset();
}


/*
  Prepare to iterate over the BNLH join cache buffer to look for matches 

  SYNOPSIS
    prepare_look_for_matches()
      skip_last   <-> ignore the last record in the buffer

  DESCRIPTION
    The function prepares the join cache for an iteration over the
    records in the join buffer. The iteration is performed when looking
    for matches for the record from the joined table join_tab that 
    has been placed into the record buffer of the joined table.
    If the value of the parameter skip_last is TRUE then the last
    record from the join buffer is ignored.
    The function builds the hashed key from the join fields of join_tab
    and uses this key to look in the hash table of the join cache for
    the chain of matching records in in the join buffer. If it finds
    such a chain it sets  the member last_rec_ref_ptr to point to the
    last link of the chain while setting the member next_rec_ref_po 0.
    
  RETURN VALUE    
    TRUE    there are no matching records in the buffer to iterate over 
    FALSE   otherwise
*/
    
bool JOIN_CACHE_BNLH::prepare_look_for_matches(bool skip_last)
{
  uchar *curr_matching_chain;
  last_matching_rec_ref_ptr= next_matching_rec_ref_ptr= 0;
  if (!(curr_matching_chain= get_matching_chain_by_join_key()))
    return 1;
  last_matching_rec_ref_ptr= get_next_rec_ref(curr_matching_chain); 
  return 0;
}


/*
  Get next record from the BNLH join cache buffer when looking for matches 

  SYNOPSIS
    get_next_candidate_for_match

  DESCRIPTION
    This method is used for iterations over the records from the join
    cache buffer when looking for matches for records from join_tab.
    The methods performs the necessary preparations to read the next record
    from the join buffer into the record buffer by the method
    read_next_candidate_for_match, or, to skip the next record from the join 
    buffer by the method skip_next_candidate_for_match.    
    This implementation of the virtual method moves to the next record
    in the chain of all records from the join buffer that are to be
    equi-joined with the current record from join_tab.
    
  RETURN VALUE   
    pointer to the beginning of the record fields in the join buffer
    if the there is another record to iterate over, 0 - otherwise.  
*/

uchar *JOIN_CACHE_BNLH::get_next_candidate_for_match()
{
  if (next_matching_rec_ref_ptr == last_matching_rec_ref_ptr)
    return 0;
  next_matching_rec_ref_ptr= get_next_rec_ref(next_matching_rec_ref_ptr ?
                                                next_matching_rec_ref_ptr :
                                                last_matching_rec_ref_ptr);
  return next_matching_rec_ref_ptr+rec_fields_offset; 
} 


/*
  Check whether the matching record from the BNLH cache is to be skipped 

  SYNOPSIS
    skip_next_candidate_for_match
    rec_ptr  pointer to the position in the join buffer right after 
             the previous record

  DESCRIPTION
    This implementation of the virtual function just calls the
    method get_match_flag_by_pos to check whether the record referenced
    by ref_ptr has its match flag set to MATCH_FOUND.

  RETURN VALUE    
    TRUE   the record referenced by rec_ptr has its match flag set to 
           MATCH_FOUND
    FALSE  otherwise  
*/

bool JOIN_CACHE_BNLH::skip_next_candidate_for_match(uchar *rec_ptr)
{
 return  join_tab->check_only_first_match() &&
          (get_match_flag_by_pos(rec_ptr) == MATCH_FOUND);
}


/*
  Read next record from the BNLH join cache buffer when looking for matches 

  SYNOPSIS
    read_next_candidate_for_match
    rec_ptr  pointer to the position in the join buffer right after 
             the previous record

  DESCRIPTION
    This implementation of the virtual method read_next_candidate_for_match
    calls the method get_record_by_pos to read the record referenced by rec_ptr
    from the join buffer into the record buffer. If this record refers to
    fields in the other join buffers the call of get_record_by_po ensures that
    these fields are read into the corresponding record buffers as well.
    This function is supposed to be called after a successful call of
    the method get_next_candidate_for_match.
    
  RETURN VALUE   
    none
*/

void JOIN_CACHE_BNLH::read_next_candidate_for_match(uchar *rec_ptr)
{
  get_record_by_pos(rec_ptr);
} 


/*
  Initialize the BNLH join cache 

  SYNOPSIS
    init

  DESCRIPTION
    The function initializes the cache structure. It is supposed to be called
    right after a constructor for the JOIN_CACHE_BNLH.

  NOTES
    The function first constructs a companion object of the type JOIN_TAB_SCAN,
    then it calls the init method of the parent class.
    
  RETURN VALUE  
    0   initialization with buffer allocations has been succeeded
    1   otherwise
*/

int JOIN_CACHE_BNLH::init()
{
  DBUG_ENTER("JOIN_CACHE_BNLH::init");

  if (!(join_tab_scan= new JOIN_TAB_SCAN(join, join_tab)))
    DBUG_RETURN(1);

  DBUG_RETURN(JOIN_CACHE_HASHED::init());
}


/* 
  Calculate the increment of the MRR buffer for a record write       

  SYNOPSIS
    aux_buffer_incr()

  DESCRIPTION
    This implementation of the virtual function aux_buffer_incr determines
    for how much the size of the MRR buffer should be increased when another
    record is added to the cache.   

  RETURN VALUE
    the increment of the size of the MRR buffer for the next record
*/

uint JOIN_TAB_SCAN_MRR::aux_buffer_incr(ulong recno)
{
  uint incr= 0;
  TABLE_REF *ref= &join_tab->ref;
  TABLE *tab= join_tab->table;
  uint rec_per_key= tab->key_info[ref->key].rec_per_key[ref->key_parts-1];
  set_if_bigger(rec_per_key, 1);
  if (recno == 1)
    incr=  ref->key_length + tab->file->ref_length;
  incr+= tab->file->stats.mrr_length_per_rec * rec_per_key;
  return incr; 
}


/* 
  Initiate iteration over records returned by MRR for the current join buffer

  SYNOPSIS
    open()

  DESCRIPTION
    The function initiates the process of iteration over the records from 
    join_tab returned by the MRR interface functions for records from
    the join buffer. Such an iteration is performed by the BKA/BKAH join
    algorithm for each new refill of the join buffer.
    The function calls the MRR handler function multi_range_read_init to
    initiate this process.

  RETURN VALUE   
    0            the initiation is a success 
    error code   otherwise     
*/

int JOIN_TAB_SCAN_MRR::open()
{
  handler *file= join_tab->table->file;

  join_tab->table->null_row= 0;


  /* Dynamic range access is never used with BKA */
  DBUG_ASSERT(join_tab->use_quick != 2);

  save_or_restore_used_tabs(join_tab, FALSE);

  init_mrr_buff();

  /* 
    Prepare to iterate over keys from the join buffer and to get
    matching candidates obtained with MMR handler functions.
  */ 
  if (!file->inited)
    file->ha_index_init(join_tab->ref.key, 1);
  ranges= cache->get_number_of_ranges_for_mrr();
  if (!join_tab->cache_idx_cond)
    range_seq_funcs.skip_index_tuple= 0;
  return file->multi_range_read_init(&range_seq_funcs, (void*) cache,
                                     ranges, mrr_mode, &mrr_buff);
}


/* 
  Read the next record returned by MRR for the current join buffer

  SYNOPSIS
    next()

  DESCRIPTION
    The function reads the next record from the joined table join_tab
    returned by the MRR handler function multi_range_read_next for
    the current refill of the join buffer. The record is read into
    the record buffer used for join_tab records in join operations.

  RETURN VALUE   
    0            the next record exists and has been successfully read 
    error code   otherwise     
*/

int JOIN_TAB_SCAN_MRR::next()
{
  char **ptr= (char **) cache->get_curr_association_ptr();

  DBUG_ASSERT(sizeof(range_id_t) == sizeof(*ptr));
  int rc= join_tab->table->file->multi_range_read_next((range_id_t*)ptr) ? -1 : 0;
  if (!rc)
  {
    /* 
      If a record in in an incremental cache contains no fields then the
      association for the last record in cache will be equal to cache->end_pos
    */ 
    DBUG_ASSERT(cache->buff <= (uchar *) (*ptr) &&
                (uchar *) (*ptr) <= cache->end_pos);
    update_virtual_fields(join->thd, join_tab->table);
  }
  return rc;
}


static 
void bka_range_seq_key_info(void *init_params, uint *length, 
                            key_part_map *map)
{
  TABLE_REF *ref= &(((JOIN_CACHE*)init_params)->join_tab->ref);
  *length= ref->key_length;
  *map= (key_part_map(1) << ref->key_parts) - 1;
}


/*
  Initialize retrieval of range sequence for BKA join algorithm
    
  SYNOPSIS
    bka_range_seq_init()
     init_params   pointer to the BKA join cache object
     n_ranges      the number of ranges obtained 
     flags         combination of MRR flags

  DESCRIPTION
    The function interprets init_param as a pointer to a JOIN_CACHE_BKA
    object. The function prepares for an iteration over the join keys
    built for all records from the cache join buffer.

  NOTE
    This function are used only as a callback function.    

  RETURN VALUE
    init_param value that is to be used as a parameter of bka_range_seq_next()
*/    

static 
range_seq_t bka_range_seq_init(void *init_param, uint n_ranges, uint flags)
{
  DBUG_ENTER("bka_range_seq_init");
  JOIN_CACHE_BKA *cache= (JOIN_CACHE_BKA *) init_param;
  cache->reset(0);
  DBUG_RETURN((range_seq_t) init_param);
}


/*
  Get the next range/key over records from the join buffer used by a BKA cache
    
  SYNOPSIS
    bka_range_seq_next()
      seq        the value returned by  bka_range_seq_init
      range  OUT reference to the next range
  
  DESCRIPTION
    The function interprets seq as a pointer to a JOIN_CACHE_BKA
    object. The function returns a pointer to the range descriptor
    for the key built over the next record from the join buffer.

  NOTE
    This function are used only as a callback function.
   
  RETURN VALUE
    FALSE   ok, the range structure filled with info about the next range/key
    TRUE    no more ranges
*/    

static 
bool bka_range_seq_next(range_seq_t rseq, KEY_MULTI_RANGE *range)
{
  DBUG_ENTER("bka_range_seq_next");
  JOIN_CACHE_BKA *cache= (JOIN_CACHE_BKA *) rseq;
  TABLE_REF *ref= &cache->join_tab->ref;
  key_range *start_key= &range->start_key;
  if ((start_key->length= cache->get_next_key((uchar **) &start_key->key)))
  {
    start_key->keypart_map= (1 << ref->key_parts) - 1;
    start_key->flag= HA_READ_KEY_EXACT;
    range->end_key= *start_key;
    range->end_key.flag= HA_READ_AFTER_KEY;
    range->ptr= (char *) cache->get_curr_rec();
    range->range_flag= EQ_RANGE;
    DBUG_RETURN(0);
  } 
  DBUG_RETURN(1);
}


/*
  Check whether range_info orders to skip the next record from BKA buffer

  SYNOPSIS
    bka_range_seq_skip_record()
      seq              value returned by bka_range_seq_init()
      range_info       information about the next range
      rowid [NOT USED] rowid of the record to be checked 

    
  DESCRIPTION
    The function interprets seq as a pointer to a JOIN_CACHE_BKA object.
    The function returns TRUE if the record with this range_info 
    is to be filtered out from the stream of records returned by 
    multi_range_read_next(). 

  NOTE
    This function are used only as a callback function.

  RETURN VALUE
    1    record with this range_info is to be filtered out from the stream
         of records returned by multi_range_read_next()
    0    the record is to be left in the stream
*/ 

static 
bool bka_range_seq_skip_record(range_seq_t rseq, range_id_t range_info, uchar *rowid)
{
  DBUG_ENTER("bka_range_seq_skip_record");
  JOIN_CACHE_BKA *cache= (JOIN_CACHE_BKA *) rseq;
  bool res= cache->get_match_flag_by_pos((uchar *) range_info) ==
            JOIN_CACHE::MATCH_FOUND;
  DBUG_RETURN(res);
}


/*
  Check if the record combination from BKA cache matches the index condition

  SYNOPSIS
    bka_skip_index_tuple()
      rseq             value returned by bka_range_seq_init()
      range_info       record chain for the next range/key returned by MRR
    
  DESCRIPTION
    This is wrapper for JOIN_CACHE_BKA::skip_index_tuple method,
    see comments there.

  NOTE
    This function is used as a RANGE_SEQ_IF::skip_index_tuple callback.
 
  RETURN VALUE
    0    The record combination satisfies the index condition
    1    Otherwise
*/

static 
bool bka_skip_index_tuple(range_seq_t rseq, range_id_t range_info)
{
  DBUG_ENTER("bka_skip_index_tuple");
  JOIN_CACHE_BKA *cache= (JOIN_CACHE_BKA *) rseq;
  bool res= cache->skip_index_tuple(range_info);
  DBUG_RETURN(res);
}


/*
  Prepare to read the record from BKA cache matching the current joined record   

  SYNOPSIS
    prepare_look_for_matches()
      skip_last <-> ignore the last record in the buffer (always unused here)

  DESCRIPTION
    The function prepares to iterate over records in the join cache buffer
    matching the record loaded into the record buffer for join_tab when
    performing join operation by BKA join algorithm. With BKA algorithms the
    record loaded into the record buffer for join_tab always has a direct
    reference to the matching records from the join buffer. When the regular
    BKA join algorithm is employed the record from join_tab can refer to
    only one such record.   
    The function sets the counter of the remaining records from the cache 
    buffer that would match the current join_tab record to 1.
    
  RETURN VALUE   
    TRUE    there are no records in the buffer to iterate over 
    FALSE   otherwise
*/
    
bool JOIN_CACHE_BKA::prepare_look_for_matches(bool skip_last)
{
  if (!records)
    return TRUE;
  rem_records= 1;
  return FALSE;
}


/*
  Get the record from the BKA cache matching the current joined record   

  SYNOPSIS
    get_next_candidate_for_match

  DESCRIPTION
    This method is used for iterations over the records from the join
    cache buffer when looking for matches for records from join_tab.
    The method performs the necessary preparations to read the next record
    from the join buffer into the record buffer by the method
    read_next_candidate_for_match, or, to skip the next record from the join 
    buffer by the method skip_if_not_needed_match.    
    This implementation of the virtual method get_next_candidate_for_match
    just  decrements the counter of the records that are to be iterated over
    and returns the value of curr_association as a reference to the position
    of the beginning of the record fields in the buffer.
    
  RETURN VALUE   
    pointer to the start of the record fields in the join buffer
    if the there is another record to iterate over, 0 - otherwise.  
*/

uchar *JOIN_CACHE_BKA::get_next_candidate_for_match()
{
  if (!rem_records)
    return 0;
  rem_records--;
  return curr_association;
} 


/*
  Check whether the matching record from the BKA cache is to be skipped 

  SYNOPSIS
    skip_next_candidate_for_match
    rec_ptr  pointer to the position in the join buffer right after 
             the previous record

  DESCRIPTION
    This implementation of the virtual function just calls the
    method get_match_flag_by_pos to check whether the record referenced
    by ref_ptr has its match flag set to MATCH_FOUND.

  RETURN VALUE   
    TRUE   the record referenced by rec_ptr has its match flag set to
           MATCH_FOUND
    FALSE  otherwise  
*/

bool JOIN_CACHE_BKA::skip_next_candidate_for_match(uchar *rec_ptr)
{
  return join_tab->check_only_first_match() && 
         (get_match_flag_by_pos(rec_ptr) == MATCH_FOUND);
}


/*
  Read the next record from the BKA join cache buffer when looking for matches 

  SYNOPSIS
    read_next_candidate_for_match
    rec_ptr  pointer to the position in the join buffer right after 
             the previous record

  DESCRIPTION
    This implementation of the virtual method read_next_candidate_for_match
    calls the method get_record_by_pos to read the record referenced by rec_ptr
    from the join buffer into the record buffer. If this record refers to
    fields in the other join buffers the call of get_record_by_po ensures that
    these fields are read into the corresponding record buffers as well.
    This function is supposed to be called after a successful call of
    the method get_next_candidate_for_match.
    
  RETURN VALUE   
    none
*/

void JOIN_CACHE_BKA::read_next_candidate_for_match(uchar *rec_ptr)
{
  get_record_by_pos(rec_ptr);
} 


/*
  Initialize the BKA join cache 

  SYNOPSIS
    init

  DESCRIPTION
    The function initializes the cache structure. It is supposed to be called
    right after a constructor for the JOIN_CACHE_BKA.

  NOTES
    The function first constructs a companion object of the type 
    JOIN_TAB_SCAN_MRR, then it calls the init method of the parent class.
    
  RETURN VALUE   
    0   initialization with buffer allocations has been succeeded
    1   otherwise
*/

int JOIN_CACHE_BKA::init()
{
  int res;
  bool check_only_first_match= join_tab->check_only_first_match();

  RANGE_SEQ_IF rs_funcs= { bka_range_seq_key_info,
                           bka_range_seq_init, 
                           bka_range_seq_next,
                           check_only_first_match ?
                             bka_range_seq_skip_record : 0,
                           bka_skip_index_tuple };

  DBUG_ENTER("JOIN_CACHE_BKA::init");

  JOIN_TAB_SCAN_MRR *jsm;
  if (!(join_tab_scan= jsm= new JOIN_TAB_SCAN_MRR(join, join_tab, 
                                                  mrr_mode, rs_funcs)))
    DBUG_RETURN(1);

  if ((res= JOIN_CACHE::init()))
    DBUG_RETURN(res);

  if (use_emb_key)
    jsm->mrr_mode |= HA_MRR_MATERIALIZED_KEYS;

  DBUG_RETURN(0);
}


/* 
  Get the key built over the next record from BKA join buffer

  SYNOPSIS
    get_next_key()
      key    pointer to the buffer where the key value is to be placed

  DESCRIPTION
    The function reads key fields from the current record in the join buffer.
    and builds the key value out of these fields that will be used to access
    the 'join_tab' table. Some of key fields may belong to previous caches.
    They are accessed via record references to the record parts stored in the
    previous join buffers. The other key fields always are placed right after
    the flag fields of the record.
    If the key is embedded, which means that its value can be read directly
    from the join buffer, then *key is set to the beginning of the key in
    this buffer. Otherwise the key is built in the join_tab->ref->key_buff.
    The function returns the length of the key if it succeeds ro read it.
    If is assumed that the functions starts reading at the position of
    the record length which is provided for each records in a BKA cache.
    After the key is built the 'pos' value points to the first position after
    the current record.
    The function just skips the records with MATCH_IMPOSSIBLE in the
    match flag field if there is any. 
    The function returns 0 if the initial position is after the beginning
    of the record fields for last record from the join buffer. 

  RETURN VALUE
    length of the key value - if the starting value of 'pos' points to
    the position before the fields for the last record,
    0 - otherwise.     
*/

uint JOIN_CACHE_BKA::get_next_key(uchar ** key)
{
  uint len;
  uint32 rec_len;
  uchar *init_pos;
  JOIN_CACHE *cache;
  
start:

  /* Any record in a BKA cache is prepended with its length */
  DBUG_ASSERT(with_length);
   
  if ((pos+size_of_rec_len) > last_rec_pos || !records)
    return 0;

  /* Read the length of the record */
  rec_len= get_rec_length(pos);
  pos+= size_of_rec_len; 
  init_pos= pos;

  /* Read a reference to the previous cache if any */
  if (prev_cache)
    pos+= prev_cache->get_size_of_rec_offset();

  curr_rec_pos= pos;

  /* Read all flag fields of the record */
  read_flag_fields();

  if (with_match_flag && 
      (Match_flag) curr_rec_pos[0] == MATCH_IMPOSSIBLE )
  {
    pos= init_pos+rec_len;
    goto start;
  }
 
  if (use_emb_key)
  {
    /* An embedded key is taken directly from the join buffer */
    *key= pos;
    len= emb_key_length;
  }
  else
  {
    /* Read key arguments from previous caches if there are any such fields */
    if (external_key_arg_fields)
    {
      uchar *rec_ptr= curr_rec_pos;
      uint key_arg_count= external_key_arg_fields;
      CACHE_FIELD **copy_ptr= blob_ptr-key_arg_count;
      for (cache= prev_cache; key_arg_count; cache= cache->prev_cache)
      { 
        uint len= 0;
        DBUG_ASSERT(cache);
        rec_ptr= cache->get_rec_ref(rec_ptr);
        while (!cache->referenced_fields)
        {
          cache= cache->prev_cache;
          DBUG_ASSERT(cache);
          rec_ptr= cache->get_rec_ref(rec_ptr);
        }
        while (key_arg_count && 
               cache->read_referenced_field(*copy_ptr, rec_ptr, &len))
        {
          copy_ptr++;
          --key_arg_count;
        }
      }
    }
    
    /* 
      Read the other key arguments from the current record. The fields for
      these arguments are always first in the sequence of the record's fields.
    */     
    CACHE_FIELD *copy= field_descr+flag_fields;
    CACHE_FIELD *copy_end= copy+local_key_arg_fields;
    bool blob_in_rec_buff= blob_data_is_in_rec_buff(curr_rec_pos);
    for ( ; copy < copy_end; copy++)
      read_record_field(copy, blob_in_rec_buff);
    
    /* Build the key over the fields read into the record buffers */ 
    TABLE_REF *ref= &join_tab->ref;
    cp_buffer_from_ref(join->thd, join_tab->table, ref);
    *key= ref->key_buff;
    len= ref->key_length;
  }

  pos= init_pos+rec_len;

  return len;
} 


/*
  Check the index condition of the joined table for a record from the BKA cache

  SYNOPSIS
    skip_index_tuple()
      range_info       pointer to the record returned by MRR 
    
  DESCRIPTION
    This function is invoked from MRR implementation to check if an index
    tuple matches the index condition. It is used in the case where the index
    condition actually depends on both columns of the used index and columns
    from previous tables.
   
  NOTES 
    Accessing columns of the previous tables requires special handling with
    BKA. The idea of BKA is to collect record combinations in a buffer and 
    then do a batch of ref access lookups, i.e. by the time we're doing a
    lookup its previous-records-combination is not in prev_table->record[0]
    but somewhere in the join buffer.    
    We need to get it from there back into prev_table(s)->record[0] before we
    can evaluate the index condition, and that's why we need this function
    instead of regular IndexConditionPushdown.

  NOTES
    Possible optimization:
    Before we unpack the record from a previous table
    check if this table is used in the condition.
    If so then unpack the record otherwise skip the unpacking.
    This should be done by a special virtual method
    get_partial_record_by_pos().

  RETURN VALUE
    1    the record combination does not satisfies the index condition
    0    otherwise
*/

bool JOIN_CACHE_BKA::skip_index_tuple(range_id_t range_info)
{
  DBUG_ENTER("JOIN_CACHE_BKA::skip_index_tuple");
  get_record_by_pos((uchar*)range_info);
  DBUG_RETURN(!join_tab->cache_idx_cond->val_int());
}



/*
  Initialize retrieval of range sequence for the BKAH join algorithm
    
  SYNOPSIS
    bkah_range_seq_init()
      init_params   pointer to the BKAH join cache object
      n_ranges      the number of ranges obtained 
      flags         combination of MRR flags

  DESCRIPTION
    The function interprets init_param as a pointer to a JOIN_CACHE_BKAH
    object. The function prepares for an iteration over distinct join keys
    built over the records from the cache join buffer.

  NOTE
    This function are used only as a callback function.    

  RETURN VALUE
    init_param    value that is to be used as a parameter of 
                  bkah_range_seq_next()
*/    

static 
range_seq_t bkah_range_seq_init(void *init_param, uint n_ranges, uint flags)
{
  DBUG_ENTER("bkah_range_seq_init");
  JOIN_CACHE_BKAH *cache= (JOIN_CACHE_BKAH *) init_param;
  cache->reset(0);
  DBUG_RETURN((range_seq_t) init_param);
}


/*
  Get the next range/key over records from the join buffer of a BKAH cache  
    
  SYNOPSIS
    bkah_range_seq_next()
      seq        value returned by  bkah_range_seq_init()
      range  OUT reference to the next range
  
  DESCRIPTION
    The function interprets seq as a pointer to a JOIN_CACHE_BKAH 
    object. The function returns a pointer to the range descriptor
    for the next unique key built over records from the join buffer.

  NOTE
    This function are used only as a callback function.
   
  RETURN VALUE
    FALSE  ok, the range structure filled with info about the next range/key
    TRUE   no more ranges
*/    

static 
bool bkah_range_seq_next(range_seq_t rseq, KEY_MULTI_RANGE *range)
{
  DBUG_ENTER("bkah_range_seq_next");
  JOIN_CACHE_BKAH *cache= (JOIN_CACHE_BKAH *) rseq;
  TABLE_REF *ref= &cache->join_tab->ref;
  key_range *start_key= &range->start_key;
  if ((start_key->length= cache->get_next_key((uchar **) &start_key->key)))
  {
    start_key->keypart_map= (1 << ref->key_parts) - 1;
    start_key->flag= HA_READ_KEY_EXACT;
    range->end_key= *start_key;
    range->end_key.flag= HA_READ_AFTER_KEY;
    range->ptr= (char *) cache->get_curr_key_chain();
    range->range_flag= EQ_RANGE;
    DBUG_RETURN(0);
  } 
  DBUG_RETURN(1);
}


/*
  Check whether range_info orders to skip the next record from BKAH join buffer

  SYNOPSIS
    bkah_range_seq_skip_record()
      seq              value returned by bkah_range_seq_init()
      range_info       information about the next range/key returned by MRR
      rowid [NOT USED] rowid of the record to be checked (not used)
    
  DESCRIPTION
    The function interprets seq as a pointer to a JOIN_CACHE_BKAH
    object. The function returns TRUE if the record with this range_info
    is to be filtered out from the stream of records returned by
    multi_range_read_next(). 

  NOTE
    This function are used only as a callback function.

  RETURN VALUE
    1    record with this range_info is to be filtered out from the stream
         of records returned by multi_range_read_next()
    0    the record is to be left in the stream
*/ 

static 
bool bkah_range_seq_skip_record(range_seq_t rseq, range_id_t range_info,
                                uchar *rowid)
{
  DBUG_ENTER("bkah_range_seq_skip_record");
  JOIN_CACHE_BKAH *cache= (JOIN_CACHE_BKAH *) rseq;
  bool res= cache->check_all_match_flags_for_key((uchar *) range_info);
  DBUG_RETURN(res);
}

 
/*
  Check if the record combination from BKAH cache matches the index condition

  SYNOPSIS
    bkah_skip_index_tuple()
      rseq             value returned by bka_range_seq_init()
      range_info       record chain for the next range/key returned by MRR
    
  DESCRIPTION
    This is wrapper for JOIN_CACHE_BKA_UNIQUE::skip_index_tuple method,
    see comments there.

  NOTE
    This function is used as a RANGE_SEQ_IF::skip_index_tuple callback.
 
  RETURN VALUE
    0    some records from the chain satisfy the index condition
    1    otherwise
*/

static 
bool bkah_skip_index_tuple(range_seq_t rseq, range_id_t range_info)
{
  DBUG_ENTER("bka_unique_skip_index_tuple");
  JOIN_CACHE_BKAH *cache= (JOIN_CACHE_BKAH *) rseq;
  DBUG_RETURN(cache->skip_index_tuple(range_info));
}


/*
  Prepare to read record from BKAH cache matching the current joined record   

  SYNOPSIS
    prepare_look_for_matches()
      skip_last <-> ignore the last record in the buffer (always unused here)

  DESCRIPTION
    The function prepares to iterate over records in the join cache buffer
    matching the record loaded into the record buffer for join_tab when
    performing join operation by BKAH join algorithm. With BKAH algorithm, if
    association labels are used, then record loaded into the record buffer 
    for join_tab always has a direct reference to the chain of the mathing
    records from the join buffer. If association labels are not used then
    then the chain of the matching records is obtained by the call of the
    get_key_chain_by_join_key function.
    
  RETURN VALUE   
    TRUE    there are no records in the buffer to iterate over 
    FALSE   otherwise
*/
    
bool JOIN_CACHE_BKAH::prepare_look_for_matches(bool skip_last)
{
  last_matching_rec_ref_ptr= next_matching_rec_ref_ptr= 0;
  if (no_association &&
      (curr_matching_chain= get_matching_chain_by_join_key()))
    return 1;
  last_matching_rec_ref_ptr= get_next_rec_ref(curr_matching_chain);
  return 0;
}

/*
  Initialize the BKAH join cache 

  SYNOPSIS
    init

  DESCRIPTION
    The function initializes the cache structure. It is supposed to be called
    right after a constructor for the JOIN_CACHE_BKAH.

  NOTES
    The function first constructs a companion object of the type 
    JOIN_TAB_SCAN_MRR, then it calls the init method of the parent class.
    
  RETURN VALUE   
    0   initialization with buffer allocations has been succeeded
    1   otherwise
*/

int JOIN_CACHE_BKAH::init()
{
  bool check_only_first_match= join_tab->check_only_first_match();

  no_association= test(mrr_mode & HA_MRR_NO_ASSOCIATION);

  RANGE_SEQ_IF rs_funcs= { bka_range_seq_key_info,
                           bkah_range_seq_init,
                           bkah_range_seq_next,
                           check_only_first_match && !no_association ?
                             bkah_range_seq_skip_record : 0,
                           bkah_skip_index_tuple };

  DBUG_ENTER("JOIN_CACHE_BKAH::init");

  if (!(join_tab_scan= new JOIN_TAB_SCAN_MRR(join, join_tab, 
                                             mrr_mode, rs_funcs)))
    DBUG_RETURN(1);

  DBUG_RETURN(JOIN_CACHE_HASHED::init());
}


/*
  Check the index condition of the joined table for a record from the BKA cache

  SYNOPSIS
    skip_index_tuple()
      range_info       record chain returned by MRR 
    
  DESCRIPTION
    See JOIN_CACHE_BKA::skip_index_tuple().
    This function is the variant for use with rhe class JOIN_CACHE_BKAH.
    The difference from JOIN_CACHE_BKA case is that there may be multiple
    previous table record combinations that share the same key(MRR range).
    As a consequence, we need to loop through the chain of all table record
    combinations that match the given MRR range key range_info until we find
    one that satisfies the index condition.

  NOTE
    Possible optimization:
    Before we unpack the record from a previous table
    check if this table is used in the condition.
    If so then unpack the record otherwise skip the unpacking.
    This should be done by a special virtual method
    get_partial_record_by_pos().

  RETURN VALUE
    1    any record combination from the chain referred by range_info
         does not satisfy the index condition
    0    otherwise


*/

bool JOIN_CACHE_BKAH::skip_index_tuple(range_id_t range_info)
{
  uchar *last_rec_ref_ptr= get_next_rec_ref((uchar*) range_info);
  uchar *next_rec_ref_ptr= last_rec_ref_ptr;
  DBUG_ENTER("JOIN_CACHE_BKAH::skip_index_tuple");
  do
  {
    next_rec_ref_ptr= get_next_rec_ref(next_rec_ref_ptr);
    uchar *rec_ptr= next_rec_ref_ptr + rec_fields_offset;
    get_record_by_pos(rec_ptr);
    if (join_tab->cache_idx_cond->val_int())
      DBUG_RETURN(FALSE);
  } while(next_rec_ref_ptr != last_rec_ref_ptr);
  DBUG_RETURN(TRUE);
}