From 25f5debdc71105820aceaac25799eb3fc09479cd Mon Sep 17 00:00:00 2001 From: Igor Babaev Date: Mon, 18 Oct 2010 13:33:05 -0700 Subject: MWL#128: Added into EXPLAIN output info about types of the used join buffers and about the employed join algorithms. Refactored constructors of the JOIN_CACHE* classes. --- mysql-test/r/group_min_max.result | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'mysql-test/r/group_min_max.result') diff --git a/mysql-test/r/group_min_max.result b/mysql-test/r/group_min_max.result index f95188b88b1..16398bd1852 100644 --- a/mysql-test/r/group_min_max.result +++ b/mysql-test/r/group_min_max.result @@ -2267,7 +2267,7 @@ ON t1_outer1.a = (SELECT max(b) FROM t1 GROUP BY a HAVING a < 2) AND t1_outer1.b = t1_outer2.b; id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY t1_outer1 ref a a 5 const 1 Using where; Using index -1 PRIMARY t1_outer2 index NULL a 10 NULL 15 Using where; Using index; Using join buffer +1 PRIMARY t1_outer2 index NULL a 10 NULL 15 Using where; Using index; Using join buffer (flat, BNL join) 2 SUBQUERY t1 range NULL a 5 NULL 8 Using index for group-by EXPLAIN SELECT (SELECT (SELECT max(b) FROM t1 GROUP BY a HAVING a < 2) x FROM t1 AS t1_outer) x2 FROM t1 AS t1_outer2; -- cgit v1.2.1 From 5c4e64a574b01a26eb95b6676874060cdbbb6193 Mon Sep 17 00:00:00 2001 From: unknown Date: Tue, 18 Jan 2011 00:53:41 +0200 Subject: MWL#89 Fixed query plans with loose index scan degraded into index scan. Analysis: With MWL#89 subqueries are no longer executed and substituted during the optimization of the outer query. As a result subquery predicates that were previously executed and substituted by a constant before the range optimizer were present as regular subquery predicates during range optimization. The procedure check_group_min_max_predicates() had a naive test that ruled out all queries with subqueries in the WHERE clause. This resulted in worse plans with MWL#89. Solution: The solution is to refine the test in check_group_min_max_predicates() to check if each MIN/MAX argument is referred to by a subquery predicate. --- mysql-test/r/group_min_max.result | 152 +++++++++++++++++++++++++++++++++++++- 1 file changed, 149 insertions(+), 3 deletions(-) (limited to 'mysql-test/r/group_min_max.result') diff --git a/mysql-test/r/group_min_max.result b/mysql-test/r/group_min_max.result index 974521ec120..38774a20832 100644 --- a/mysql-test/r/group_min_max.result +++ b/mysql-test/r/group_min_max.result @@ -1360,12 +1360,158 @@ group by a1,a2,b; id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY t1 index NULL idx_t1_1 163 NULL 128 Using where; Using index 2 DEPENDENT SUBQUERY t2 index NULL idx_t2_1 163 NULL 164 Using where; Using index +select a1,a2,b,min(c),max(c) from t1 +where exists ( select * from t2 where t2.c = t1.c ) +group by a1,a2,b; +a1 a2 b min(c) max(c) +a a a a111 d111 +a a b e112 h112 +a b a i121 l121 +a b b m122 p122 +b a a a211 d211 +b a b e212 h212 +b b a i221 l221 +b b b m222 p222 +c a a a311 d311 +c a b e312 h312 +c b a i321 l321 +c b b m322 p322 +d a a a411 d411 +d a b e412 h412 +d b a i421 l421 +d b b m422 p422 explain select a1,a2,b,min(c),max(c) from t1 where exists ( select * from t2 where t2.c > 'b1' ) group by a1,a2,b; id select_type table type possible_keys key key_len ref rows Extra -1 PRIMARY t1 range NULL idx_t1_1 147 NULL 17 Using index for group-by +1 PRIMARY t1 range NULL idx_t1_1 147 NULL 17 Using where; Using index for group-by 2 SUBQUERY t2 index NULL idx_t2_1 163 NULL 164 Using where; Using index +select a1,a2,b,min(c),max(c) from t1 +where exists ( select * from t2 where t2.c > 'b1' ) +group by a1,a2,b; +a1 a2 b min(c) max(c) +a a a a111 d111 +a a b e112 h112 +a b a i121 l121 +a b b m122 p122 +b a a a211 d211 +b a b e212 h212 +b b a i221 l221 +b b b m222 p222 +c a a a311 d311 +c a b e312 h312 +c b a i321 l321 +c b b m322 p322 +d a a a411 d411 +d a b e412 h412 +d b a i421 l421 +d b b m422 p422 +explain select a1,a2,b,c,min(c), max(c) from t1 +where exists ( select * from t2 where t1.b > 'a' and t2.c > 'b1' ) +group by a1,a2,b; +id select_type table type possible_keys key key_len ref rows Extra +1 PRIMARY t1 range NULL idx_t1_1 147 NULL 17 Using where; Using index for group-by +2 DEPENDENT SUBQUERY t2 index NULL idx_t2_1 163 NULL 164 Using where; Using index +select a1,a2,b,c,min(c), max(c) from t1 +where exists ( select * from t2 where t1.b > 'a' and t2.c > 'b1' ) +group by a1,a2,b; +a1 a2 b c min(c) max(c) +a a b h112 e112 h112 +a b b p122 m122 p122 +b a b h212 e212 h212 +b b b p222 m222 p222 +c a b h312 e312 h312 +c b b p322 m322 p322 +d a b h412 e412 h412 +d b b p422 m422 p422 +explain select a1,a2,b,c,min(c), max(c) from t1 +where exists ( select * from t2 +where t2.c in (select c from t3 where t3.c > t1.b) and +t2.c > 'b1' ) +group by a1,a2,b; +id select_type table type possible_keys key key_len ref rows Extra +1 PRIMARY t1 range NULL idx_t1_1 147 NULL 17 Using where; Using index for group-by +2 DEPENDENT SUBQUERY t2 index NULL idx_t2_1 163 NULL 164 Using where; Using index +2 DEPENDENT SUBQUERY t3 index NULL idx_t3_1 10 NULL 192 Using where; Using index; FirstMatch(t2) +select a1,a2,b,c,min(c), max(c) from t1 +where exists ( select * from t2 +where t2.c in (select c from t3 where t3.c > t1.b) and +t2.c > 'b1' ) +group by a1,a2,b; +a1 a2 b c min(c) max(c) +a a a d111 a111 d111 +a a b h112 e112 h112 +a b a l121 i121 l121 +a b b p122 m122 p122 +b a a d211 a211 d211 +b a b h212 e212 h212 +b b a l221 i221 l221 +b b b p222 m222 p222 +c a a d311 a311 d311 +c a b h312 e312 h312 +c b a l321 i321 l321 +c b b p322 m322 p322 +d a a d411 a411 d411 +d a b h412 e412 h412 +d b a l421 i421 l421 +d b b p422 m422 p422 +explain select a1,a2,b,c,min(c), max(c) from t1 +where exists ( select * from t2 where t1.c > 'a' and t2.c > 'b1' ) +group by a1,a2,b; +id select_type table type possible_keys key key_len ref rows Extra +1 PRIMARY t1 index NULL idx_t1_1 163 NULL 128 Using where; Using index +2 DEPENDENT SUBQUERY t2 index NULL idx_t2_1 163 NULL 164 Using where; Using index +select a1,a2,b,c,min(c), max(c) from t1 +where exists ( select * from t2 where t1.c > 'a' and t2.c > 'b1' ) +group by a1,a2,b; +a1 a2 b c min(c) max(c) +a a a a111 a111 d111 +a a b e112 e112 h112 +a b a i121 i121 l121 +a b b m122 m122 p122 +b a a a211 a211 d211 +b a b e212 e212 h212 +b b a i221 i221 l221 +b b b m222 m222 p222 +c a a a311 a311 d311 +c a b e312 e312 h312 +c b a i321 i321 l321 +c b b m322 m322 p322 +d a a a411 a411 d411 +d a b e412 e412 h412 +d b a i421 i421 l421 +d b b m422 m422 p422 +explain select a1,a2,b,c,min(c), max(c) from t1 +where exists ( select * from t2 +where t2.c in (select c from t3 where t3.c > t1.c) and +t2.c > 'b1' ) +group by a1,a2,b; +id select_type table type possible_keys key key_len ref rows Extra +1 PRIMARY t1 index NULL idx_t1_1 163 NULL 128 Using where; Using index +2 DEPENDENT SUBQUERY t2 index NULL idx_t2_1 163 NULL 164 Using where; Using index +2 DEPENDENT SUBQUERY t3 index NULL idx_t3_1 10 NULL 192 Using where; Using index; FirstMatch(t2) +select a1,a2,b,c,min(c), max(c) from t1 +where exists ( select * from t2 +where t2.c in (select c from t3 where t3.c > t1.c) and +t2.c > 'b1' ) +group by a1,a2,b; +a1 a2 b c min(c) max(c) +a a a a111 a111 d111 +a a b e112 e112 h112 +a b a i121 i121 l121 +a b b m122 m122 p122 +b a a a211 a211 d211 +b a b e212 e212 h212 +b b a i221 i221 l221 +b b b m222 m222 p222 +c a a a311 a311 d311 +c a b e312 e312 h312 +c b a i321 i321 l321 +c b b m322 m322 o322 +d a a a411 a411 d411 +d a b e412 e412 h412 +d b a i421 i421 l421 +d b b m422 m422 o422 explain select a1,a2,b,min(c),max(c) from t1 where (a1 >= 'c' or a2 < 'b') and (b > 'a') group by a1,a2,b; id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE t1 range idx_t1_0,idx_t1_1,idx_t1_2 idx_t1_1 147 NULL 17 Using where; Using index for group-by @@ -2246,11 +2392,11 @@ EXPLAIN SELECT 1 FROM t1 AS t1_outer WHERE EXISTS (SELECT max(b) FROM t1 GROUP BY a HAVING a < 2); id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY t1_outer index NULL a 10 NULL 15 Using index -2 SUBQUERY t1 index NULL a 10 NULL 15 Using index +2 SUBQUERY t1 index NULL a 10 NULL 1 Using index EXPLAIN SELECT 1 FROM t1 AS t1_outer WHERE (SELECT max(b) FROM t1 GROUP BY a HAVING a < 2) > 12; id select_type table type possible_keys key key_len ref rows Extra -1 PRIMARY NULL NULL NULL NULL NULL NULL NULL Impossible WHERE +1 PRIMARY t1_outer index NULL a 10 NULL 15 Using index 2 SUBQUERY t1 range NULL a 5 NULL 8 Using index for group-by EXPLAIN SELECT 1 FROM t1 AS t1_outer WHERE a IN (SELECT max(b) FROM t1 GROUP BY a HAVING a < 2); -- cgit v1.2.1 From 648e604615dfe852abbd467dbd8e6c3c9476dd07 Mon Sep 17 00:00:00 2001 From: unknown Date: Thu, 3 Feb 2011 17:00:28 +0200 Subject: MWL#89 Adjusted test cases in accordance with the implementation. --- mysql-test/r/group_min_max.result | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'mysql-test/r/group_min_max.result') diff --git a/mysql-test/r/group_min_max.result b/mysql-test/r/group_min_max.result index 38774a20832..20b0c054480 100644 --- a/mysql-test/r/group_min_max.result +++ b/mysql-test/r/group_min_max.result @@ -2402,7 +2402,7 @@ EXPLAIN SELECT 1 FROM t1 AS t1_outer WHERE a IN (SELECT max(b) FROM t1 GROUP BY a HAVING a < 2); id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY t1_outer index NULL a 10 NULL 15 Using where; Using index -2 SUBQUERY t1 range NULL a 5 NULL 8 Using index for group-by +2 DEPENDENT SUBQUERY t1 index NULL a 10 NULL 1 Using index EXPLAIN SELECT 1 FROM t1 AS t1_outer GROUP BY a HAVING a > (SELECT max(b) FROM t1 GROUP BY a HAVING a < 2); id select_type table type possible_keys key key_len ref rows Extra -- cgit v1.2.1 From 4a9c027ad85597e5bcd42b59245a743366af476a Mon Sep 17 00:00:00 2001 From: unknown Date: Tue, 17 May 2011 00:00:11 +0300 Subject: Fix LP BUG#778413 Analysis: The subquery is evaluated first during ref-optimization of the outer query because the subquery is considered constant from the perspective of the outer query. Thus an attempt is made to evaluate the MAX subquery and use the new constant to drive an index nested loops join. During this evaluation the inner-most subquery replaces the JOIN_TAB with a new one that fetches the data from a temp table. The function select_describe crashes at the lines: TABLE_LIST *real_table= table->pos_in_table_list; item_list.push_back(new Item_string(real_table->alias, strlen(real_table->alias), cs)); because 'table' is a temp table, and it has no corresponding table reference. This 'real_table' is NULL, and real_table->alias results in a crash. Solution: In the spirit of MWL#89 prevent the evaluation of expensive predicates during optimization. This patch prevents the evaluation of expensive predicates during ref optimization. sql/item_subselect.h: Remove unused class member. Not needed for the fix, but noticed now and removed. --- mysql-test/r/group_min_max.result | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'mysql-test/r/group_min_max.result') diff --git a/mysql-test/r/group_min_max.result b/mysql-test/r/group_min_max.result index 20b0c054480..0b3df689089 100644 --- a/mysql-test/r/group_min_max.result +++ b/mysql-test/r/group_min_max.result @@ -2412,7 +2412,7 @@ EXPLAIN SELECT 1 FROM t1 AS t1_outer1 JOIN t1 AS t1_outer2 ON t1_outer1.a = (SELECT max(b) FROM t1 GROUP BY a HAVING a < 2) AND t1_outer1.b = t1_outer2.b; id select_type table type possible_keys key key_len ref rows Extra -1 PRIMARY t1_outer1 ref a a 5 const 1 Using where; Using index +1 PRIMARY t1_outer1 ref a a 5 const 1 Using index 1 PRIMARY t1_outer2 index NULL a 10 NULL 15 Using where; Using index; Using join buffer (flat, BNL join) 2 SUBQUERY t1 range NULL a 5 NULL 8 Using index for group-by EXPLAIN SELECT (SELECT (SELECT max(b) FROM t1 GROUP BY a HAVING a < 2) x -- cgit v1.2.1 From 59784abeadc4014f357e44ae507c62dc93c641b3 Mon Sep 17 00:00:00 2001 From: unknown Date: Mon, 4 Jul 2011 14:51:16 +0300 Subject: Fix LP bug lp:802979 Analysis: This bug consists of two related problems that are result of too early evaluation of single-row subqueries during the optimization phase of the outer query. Several optimizer code paths try to evaluate single-row subqueries in order to produce a constant and use that constant for further optimzation. When the execution of the subquery peforms destructive changes to the representation of the subquery, and these changes are not anticipated by the subsequent optimization phases of the outer query, we tipically get a crash or failed assert. Specifically, in this bug the inner-most suqbuery with DISTINCT triggers a substitution of the original JOIN object by a single-table JOIN object with a temp table needed to perform the DISTINCT operation (created by JOIN::make_simple_join). This substitution breaks EXPLAIN because: a) in the first example JOIN::cleanup no longer can reach the original table of the innermost subquery, and close all indexes, and b) in this second test query, EXPLAIN attempts to print the name of the internal temp table, and crashes because the temp table has no name (NULL pointer instead). Solution: a) fully disable subquery evaluation during optimization in all cases - both for constant propagation and range optimization, and b) change JOIN::join_free() to perform cleanup irrespective of EXPLAIN or not. --- mysql-test/r/group_min_max.result | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) (limited to 'mysql-test/r/group_min_max.result') diff --git a/mysql-test/r/group_min_max.result b/mysql-test/r/group_min_max.result index 0b3df689089..d3068543619 100644 --- a/mysql-test/r/group_min_max.result +++ b/mysql-test/r/group_min_max.result @@ -2412,7 +2412,7 @@ EXPLAIN SELECT 1 FROM t1 AS t1_outer1 JOIN t1 AS t1_outer2 ON t1_outer1.a = (SELECT max(b) FROM t1 GROUP BY a HAVING a < 2) AND t1_outer1.b = t1_outer2.b; id select_type table type possible_keys key key_len ref rows Extra -1 PRIMARY t1_outer1 ref a a 5 const 1 Using index +1 PRIMARY t1_outer1 ref a a 5 const 2 Using where; Using index 1 PRIMARY t1_outer2 index NULL a 10 NULL 15 Using where; Using index; Using join buffer (flat, BNL join) 2 SUBQUERY t1 range NULL a 5 NULL 8 Using index for group-by EXPLAIN SELECT (SELECT (SELECT max(b) FROM t1 GROUP BY a HAVING a < 2) x @@ -2749,7 +2749,7 @@ NULL EXPLAIN SELECT MIN( a ) FROM t1 WHERE a = (SELECT a FROM t1 WHERE a < 0); id select_type table type possible_keys key key_len ref rows Extra -x x x x x x x x x Impossible WHERE noticed after reading const tables +x x x x x x x x x Using where; Using index x x x x x x x x x Using where; Using index SELECT MIN( a ) FROM t1 WHERE a = (SELECT a FROM t1 WHERE a < 0); MIN( a ) @@ -2821,7 +2821,7 @@ NULL EXPLAIN SELECT MIN( a ) FROM t1 WHERE a = (SELECT a FROM t1 WHERE a < 0); id select_type table type possible_keys key key_len ref rows Extra -x x x x x x x x x Impossible WHERE noticed after reading const tables +x x x x x x x x x Using where; Using index x x x x x x x x x Using where; Using index SELECT MIN( a ) FROM t1 WHERE a = (SELECT a FROM t1 WHERE a < 0); MIN( a ) -- cgit v1.2.1 From c1de6f8b775eba12e09de856078d135e34aa816d Mon Sep 17 00:00:00 2001 From: Sergey Petrunya Date: Tue, 5 Jul 2011 01:44:15 +0400 Subject: Change the default @@optimizer_switch setting from semijoin=on,firstmatch=on,loosescan=on to semijoin=off,firstmatch=off,loosescan=off Adjust the testcases: - Modify subselect*.test and join_cache.test so that all tests use the same execution paths as before (i.e. optimizations that are being tested are enabled) - Let all other test files run with the new default settings (i.e. with new optimizations disabled) - Copy subquery testcases from these files into t/subselect_extra.test which will run them with new optimizations enabled. --- mysql-test/r/group_min_max.result | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'mysql-test/r/group_min_max.result') diff --git a/mysql-test/r/group_min_max.result b/mysql-test/r/group_min_max.result index 0b3df689089..c33e632ffbb 100644 --- a/mysql-test/r/group_min_max.result +++ b/mysql-test/r/group_min_max.result @@ -1432,7 +1432,7 @@ group by a1,a2,b; id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY t1 range NULL idx_t1_1 147 NULL 17 Using where; Using index for group-by 2 DEPENDENT SUBQUERY t2 index NULL idx_t2_1 163 NULL 164 Using where; Using index -2 DEPENDENT SUBQUERY t3 index NULL idx_t3_1 10 NULL 192 Using where; Using index; FirstMatch(t2) +3 DEPENDENT SUBQUERY t3 index NULL idx_t3_1 10 NULL 192 Using where; Using index select a1,a2,b,c,min(c), max(c) from t1 where exists ( select * from t2 where t2.c in (select c from t3 where t3.c > t1.b) and @@ -1489,7 +1489,7 @@ group by a1,a2,b; id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY t1 index NULL idx_t1_1 163 NULL 128 Using where; Using index 2 DEPENDENT SUBQUERY t2 index NULL idx_t2_1 163 NULL 164 Using where; Using index -2 DEPENDENT SUBQUERY t3 index NULL idx_t3_1 10 NULL 192 Using where; Using index; FirstMatch(t2) +3 DEPENDENT SUBQUERY t3 index NULL idx_t3_1 10 NULL 192 Using where; Using index select a1,a2,b,c,min(c), max(c) from t1 where exists ( select * from t2 where t2.c in (select c from t3 where t3.c > t1.c) and -- cgit v1.2.1 From 0e19f3e36f7842583feb6bead2c2600cd620bced Mon Sep 17 00:00:00 2001 From: Sergey Petrunya Date: Fri, 5 Aug 2011 22:01:49 +0400 Subject: Backport of: revno: 2876.47.174 revision-id: jorgen.loland@oracle.com-20110519120355-qn7eprkad9jqwu5j parent: mayank.prasad@oracle.com-20110518143645-bdxv4udzrmqsjmhq committer: Jorgen Loland branch nick: mysql-trunk-11765831 timestamp: Thu 2011-05-19 14:03:55 +0200 message: BUG#11765831: 'RANGE ACCESS' MAY INCORRECTLY FILTER AWAY QUALIFYING ROWS The problem was that the ranges created when OR'ing two conditions could be incorrect. Without the bugfix, "I <> 6 OR (I <> 8 AND J = 5)" would create these ranges: "NULL < I < 6", "6 <= I <= 6 AND 5 <= J <= 5", "6 < I < 8", "8 <= I <= 8 AND 5 <= J <= 5", "8 < I" While the correct ranges is "NULL < I < 6", "6 <= I <= 6 AND 5 <= J <= 5", "6 < I" The problem occurs when key_or() ORs (1) "NULL < I < 6, 6 <= I <= 6 AND 5 <= J <= 5, 6 < I" with (2) "8 < I AND 5 <= J <= 5" The reason for the bug is that in key_or(), SEL_ARG *tmp is used to point to the range in (1) above that is merged with (2) while key1 points to the root of the red-black tree of (1). When merging (1) and (2), tmp refers to the "6 < I" part whereas the root is the "6 <= ... AND 5 <= J <= 5" part. key_or() decides that the tmp range needs to be split into "6 < I < 8, 8 <= I <= 8, 8 < I", in which next_key_part of the second range should be that of tmp. However, next_key_part is set to key1->next_key_part ("5 <= J <= 5") instead of tmp->next_key_part (empty). Fixing this gives the correct but not optimal ranges: "NULL < I < 6", "6 <= I <= 6 AND 5 <= J <= 5", "6 < I < 8", "8 <= I <= 8", "8 < I" A second problem can be seen above: key_or() may create adjacent ranges that could be replaced with a single range. Fixes for this is also included in the patch so that the range above becomes correct AND optimal: "NULL < I < 6", "6 <= I <= 6 AND 5 <= J <= 5", "6 < I" Merging adjacent ranges like this gives a slightly lower cost estimate for the range access. --- mysql-test/r/group_min_max.result | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) (limited to 'mysql-test/r/group_min_max.result') diff --git a/mysql-test/r/group_min_max.result b/mysql-test/r/group_min_max.result index 7cd0011427e..6850d7c1993 100644 --- a/mysql-test/r/group_min_max.result +++ b/mysql-test/r/group_min_max.result @@ -876,10 +876,10 @@ id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE t1 range NULL idx_t1_1 163 NULL 17 Using where; Using index for group-by explain select a1,a2,b, max(c) from t1 where (c > 'b1') or (c <= 'g1') group by a1,a2,b; id select_type table type possible_keys key key_len ref rows Extra -1 SIMPLE t1 range NULL idx_t1_1 163 NULL 17 Using where; Using index for group-by +1 SIMPLE t1 range NULL idx_t1_1 147 NULL 17 Using where; Using index for group-by explain select a1,a2,b,min(c),max(c) from t1 where (c > 'b1') or (c <= 'g1') group by a1,a2,b; id select_type table type possible_keys key key_len ref rows Extra -1 SIMPLE t1 range NULL idx_t1_1 163 NULL 17 Using where; Using index for group-by +1 SIMPLE t1 range NULL idx_t1_1 147 NULL 17 Using where; Using index for group-by explain select a1,a2,b,min(c),max(c) from t1 where (c > 'b111') and (c <= 'g112') group by a1,a2,b; id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE t1 range NULL idx_t1_1 163 NULL 17 Using where; Using index for group-by @@ -924,7 +924,7 @@ id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE t2 range NULL idx_t2_1 163 NULL # Using where; Using index for group-by explain select a1,a2,b, max(c) from t2 where (c > 'b1') or (c <= 'g1') group by a1,a2,b; id select_type table type possible_keys key key_len ref rows Extra -1 SIMPLE t2 range NULL idx_t2_1 163 NULL # Using where; Using index for group-by +1 SIMPLE t2 range NULL idx_t2_1 146 NULL # Using where; Using index for group-by explain select a1,a2,b,min(c),max(c) from t2 where (c > 'b1') or (c <= 'g1') group by a1,a2,b; id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE t2 range NULL idx_t2_1 163 NULL # Using where; Using index for group-by -- cgit v1.2.1