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author | Sergei Petrunia <sergey@mariadb.com> | 2023-01-26 12:04:28 +0300 |
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committer | Sergei Petrunia <sergey@mariadb.com> | 2023-01-26 12:04:28 +0300 |
commit | 678f2220cc25b3495f1f16fe2732e49a0cd120f8 (patch) | |
tree | 8ed3d31a3510238aeaaefe23ca6f8dfc22d7a3a0 | |
parent | 765291d63e0c2a10c513a354e9ecb2e905570775 (diff) | |
download | mariadb-git-bb-10.4-mdev30218-part2.tar.gz |
MDEV-30218: Incorrect optimization for rowid_filtering, correctionbb-10.4-mdev30218-part2
Enable use of Rowid Filter optimization with eq_ref access.
Use the following assumptions:
- Assume index-only access cost is 50% of non-index-only access cost.
- Take into account that "Eq_ref access cache" reduces the number of
lookups eq_ref access will make.
= This means the number of Rowid Filter checks is reduced also
= Eq_ref access cost is computed using that assumption (see
prev_record_reads() call), so we should use it in all cost '
computations.
-rw-r--r-- | mysql-test/main/rowid_filter.result | 58 | ||||
-rw-r--r-- | mysql-test/main/subselect2.result | 2 | ||||
-rw-r--r-- | sql/sql_select.cc | 28 |
3 files changed, 73 insertions, 15 deletions
diff --git a/mysql-test/main/rowid_filter.result b/mysql-test/main/rowid_filter.result index 2bfc5b1f20c..b35021b8513 100644 --- a/mysql-test/main/rowid_filter.result +++ b/mysql-test/main/rowid_filter.result @@ -336,7 +336,7 @@ WHERE l_shipdate BETWEEN '1997-01-01' AND '1997-01-31' AND o_totalprice between 200000 and 230000; id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE lineitem range PRIMARY,i_l_shipdate,i_l_orderkey,i_l_orderkey_quantity i_l_shipdate 4 NULL 98 Using index condition -1 SIMPLE orders eq_ref PRIMARY,i_o_totalprice PRIMARY 4 dbt3_s001.lineitem.l_orderkey 1 Using where +1 SIMPLE orders eq_ref|filter PRIMARY,i_o_totalprice PRIMARY|i_o_totalprice 4|9 dbt3_s001.lineitem.l_orderkey 1 (5%) Using where; Using rowid filter set statement optimizer_switch='rowid_filter=on' for EXPLAIN FORMAT=JSON SELECT o_orderkey, l_linenumber, l_shipdate, o_totalprice FROM orders JOIN lineitem ON o_orderkey=l_orderkey WHERE l_shipdate BETWEEN '1997-01-01' AND '1997-01-31' AND @@ -369,6 +369,14 @@ EXPLAIN "key_length": "4", "used_key_parts": ["o_orderkey"], "ref": ["dbt3_s001.lineitem.l_orderkey"], + "rowid_filter": { + "range": { + "key": "i_o_totalprice", + "used_key_parts": ["o_totalprice"] + }, + "rows": 69, + "selectivity_pct": 4.6 + }, "rows": 1, "filtered": 4.6, "attached_condition": "orders.o_totalprice between 200000 and 230000" @@ -381,7 +389,7 @@ WHERE l_shipdate BETWEEN '1997-01-01' AND '1997-01-31' AND o_totalprice between 200000 and 230000; id select_type table type possible_keys key key_len ref rows r_rows filtered r_filtered Extra 1 SIMPLE lineitem range PRIMARY,i_l_shipdate,i_l_orderkey,i_l_orderkey_quantity i_l_shipdate 4 NULL 98 98.00 100.00 100.00 Using index condition -1 SIMPLE orders eq_ref PRIMARY,i_o_totalprice PRIMARY 4 dbt3_s001.lineitem.l_orderkey 1 1.00 4.60 11.22 Using where +1 SIMPLE orders eq_ref|filter PRIMARY,i_o_totalprice PRIMARY|i_o_totalprice 4|9 dbt3_s001.lineitem.l_orderkey 1 (5%) 0.11 (10%) 4.60 100.00 Using where; Using rowid filter set statement optimizer_switch='rowid_filter=on' for ANALYZE FORMAT=JSON SELECT o_orderkey, l_linenumber, l_shipdate, o_totalprice FROM orders JOIN lineitem ON o_orderkey=l_orderkey WHERE l_shipdate BETWEEN '1997-01-01' AND '1997-01-31' AND @@ -420,12 +428,25 @@ ANALYZE "key_length": "4", "used_key_parts": ["o_orderkey"], "ref": ["dbt3_s001.lineitem.l_orderkey"], + "rowid_filter": { + "range": { + "key": "i_o_totalprice", + "used_key_parts": ["o_totalprice"] + }, + "rows": 69, + "selectivity_pct": 4.6, + "r_rows": 71, + "r_lookups": 96, + "r_selectivity_pct": 10.417, + "r_buffer_size": "REPLACED", + "r_filling_time_ms": "REPLACED" + }, "r_loops": 98, "rows": 1, - "r_rows": 1, + "r_rows": 0.1122, "r_total_time_ms": "REPLACED", "filtered": 4.6, - "r_filtered": 11.224, + "r_filtered": 100, "attached_condition": "orders.o_totalprice between 200000 and 230000" } } @@ -569,7 +590,7 @@ l_quantity > 45 AND o_totalprice between 180000 and 230000; id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE lineitem range|filter PRIMARY,i_l_shipdate,i_l_orderkey,i_l_orderkey_quantity,i_l_quantity i_l_shipdate|i_l_quantity 4|9 NULL 509 (12%) Using index condition; Using where; Using rowid filter -1 SIMPLE orders eq_ref PRIMARY,i_o_totalprice PRIMARY 4 dbt3_s001.lineitem.l_orderkey 1 Using where +1 SIMPLE orders eq_ref|filter PRIMARY,i_o_totalprice PRIMARY|i_o_totalprice 4|9 dbt3_s001.lineitem.l_orderkey 1 (9%) Using where; Using rowid filter set statement optimizer_switch='rowid_filter=on' for EXPLAIN FORMAT=JSON SELECT o_orderkey, l_linenumber, l_shipdate, l_quantity, o_totalprice FROM orders JOIN lineitem ON o_orderkey=l_orderkey WHERE l_shipdate BETWEEN '1997-01-01' AND '1997-06-30' AND @@ -613,6 +634,14 @@ EXPLAIN "key_length": "4", "used_key_parts": ["o_orderkey"], "ref": ["dbt3_s001.lineitem.l_orderkey"], + "rowid_filter": { + "range": { + "key": "i_o_totalprice", + "used_key_parts": ["o_totalprice"] + }, + "rows": 139, + "selectivity_pct": 9.2667 + }, "rows": 1, "filtered": 9.2667, "attached_condition": "orders.o_totalprice between 180000 and 230000" @@ -626,7 +655,7 @@ l_quantity > 45 AND o_totalprice between 180000 and 230000; id select_type table type possible_keys key key_len ref rows r_rows filtered r_filtered Extra 1 SIMPLE lineitem range|filter PRIMARY,i_l_shipdate,i_l_orderkey,i_l_orderkey_quantity,i_l_quantity i_l_shipdate|i_l_quantity 4|9 NULL 509 (12%) 60.00 (11%) 11.69 100.00 Using index condition; Using where; Using rowid filter -1 SIMPLE orders eq_ref PRIMARY,i_o_totalprice PRIMARY 4 dbt3_s001.lineitem.l_orderkey 1 1.00 9.27 26.67 Using where +1 SIMPLE orders eq_ref|filter PRIMARY,i_o_totalprice PRIMARY|i_o_totalprice 4|9 dbt3_s001.lineitem.l_orderkey 1 (9%) 0.27 (25%) 9.27 100.00 Using where; Using rowid filter set statement optimizer_switch='rowid_filter=on' for ANALYZE FORMAT=JSON SELECT o_orderkey, l_linenumber, l_shipdate, l_quantity, o_totalprice FROM orders JOIN lineitem ON o_orderkey=l_orderkey WHERE l_shipdate BETWEEN '1997-01-01' AND '1997-06-30' AND @@ -681,12 +710,25 @@ ANALYZE "key_length": "4", "used_key_parts": ["o_orderkey"], "ref": ["dbt3_s001.lineitem.l_orderkey"], + "rowid_filter": { + "range": { + "key": "i_o_totalprice", + "used_key_parts": ["o_totalprice"] + }, + "rows": 139, + "selectivity_pct": 9.2667, + "r_rows": 144, + "r_lookups": 59, + "r_selectivity_pct": 25.424, + "r_buffer_size": "REPLACED", + "r_filling_time_ms": "REPLACED" + }, "r_loops": 60, "rows": 1, - "r_rows": 1, + "r_rows": 0.2667, "r_total_time_ms": "REPLACED", "filtered": 9.2667, - "r_filtered": 26.667, + "r_filtered": 100, "attached_condition": "orders.o_totalprice between 180000 and 230000" } } diff --git a/mysql-test/main/subselect2.result b/mysql-test/main/subselect2.result index 55ac483157f..c54d635230f 100644 --- a/mysql-test/main/subselect2.result +++ b/mysql-test/main/subselect2.result @@ -132,7 +132,7 @@ id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY t3 eq_ref PRIMARY,FFOLDERID_IDX,CMFLDRPARNT_IDX PRIMARY 34 test.t3.PARENTID 1 Using where 1 PRIMARY t3 eq_ref PRIMARY,FFOLDERID_IDX,CMFLDRPARNT_IDX PRIMARY 34 test.t3.PARENTID 1 Using where 1 PRIMARY t3 eq_ref PRIMARY,FFOLDERID_IDX,CMFLDRPARNT_IDX PRIMARY 34 test.t3.PARENTID 1 Using where -1 PRIMARY t3 eq_ref PRIMARY,FFOLDERID_IDX,CMFLDRPARNT_IDX PRIMARY 34 test.t3.PARENTID 1 Using where +1 PRIMARY t3 ref|filter PRIMARY,FFOLDERID_IDX,CMFLDRPARNT_IDX FFOLDERID_IDX|CMFLDRPARNT_IDX 34|35 test.t3.PARENTID 1 (29%) Using where; Using rowid filter drop table t1, t2, t3, t4; CREATE TABLE t1 (a int(10) , PRIMARY KEY (a)) Engine=InnoDB; INSERT INTO t1 VALUES (1),(2); diff --git a/sql/sql_select.cc b/sql/sql_select.cc index eb54484fa51..217d02bfa8d 100644 --- a/sql/sql_select.cc +++ b/sql/sql_select.cc @@ -7891,7 +7891,27 @@ best_access_path(JOIN *join, (s->table->file->index_flags(start_key->key,0,1) & HA_DO_RANGE_FILTER_PUSHDOWN)) { - double rows= record_count * records; + double rows; + if (type == JT_EQ_REF) + { + /* + Treat EQ_REF access in a special way: + 1. We have no cost for index-only read. Assume its cost is 50% of + the cost of the full read. + + 2. A regular ref access will do #record_count lookups, but eq_ref + has "lookup cache" which reduces the number of lookups made. + The estimation code uses prev_record_reads() call to estimate: + + tmp = prev_record_reads(join_positions, idx, found_ref); + + Set the effective number of rows from "tmp" here. + */ + keyread_tmp= tmp/ 2; + rows= tmp; + } + else + rows= record_count * records; /* If we use filter F with selectivity s the the cost of fetching data @@ -7934,10 +7954,6 @@ best_access_path(JOIN *join, we cannot use filters as the cost calculation below would cause tmp to become negative. The future resultion is to not limit cost with worst_seek. - - We cannot use filter with JT_EQ_REF as in this case 'tmp' is - number of rows from prev_record_read() and keyread_tmp is 0. These - numbers are not usable with rowid filter code. */ double access_cost_factor= MY_MIN((rows - keyread_tmp) / rows, 1.0); if (!(records < s->worst_seeks && @@ -7945,7 +7961,7 @@ best_access_path(JOIN *join, trace_access_idx.add("rowid_filter_skipped", "worst/max seeks clipping"); else if (access_cost_factor <= 0.0) trace_access_idx.add("rowid_filter_skipped", "cost_factor <= 0"); - else if (type != JT_EQ_REF) + else { filter= table->best_range_rowid_filter_for_partial_join(start_key->key, |