diff options
author | Monty <monty@mariadb.org> | 2022-12-27 14:49:27 +0200 |
---|---|---|
committer | Monty <monty@mariadb.org> | 2023-02-10 12:58:50 +0200 |
commit | 3fa99f0c0e294297557e5edcc31d26d2430d4c3c (patch) | |
tree | 5f4408a40652cc6b2fbbffd952caf713000e1755 /mysql-test/main/subselect_no_mat.result | |
parent | b5df077e8555c2a43e5cae7bcb58310c25119ea7 (diff) | |
download | mariadb-git-3fa99f0c0e294297557e5edcc31d26d2430d4c3c.tar.gz |
Change cost for REF to take into account cost for 1 extra key read_next
The main difference in code path between EQ_REF and REF is that for
REF we have to do an extra read_next on the index to check that there
is no more matching rows.
Before this patch we added a preference of EQ_REF by ensuring that REF
would always estimate to find at least 2 rows.
This patch adds the cost of the extra key read_next to REF access and
removes the code that limited REF to at least 2 rows. For some queries
this can have a big effect as the total estimated rows will be halved
for each REF table with 1 rows.
multi_range cost calculations are also changed to take into account
the difference between EQ_REF and REF.
The effect of the patch to the test suite:
- About 80 test case changed
- Almost all changes where for EXPLAIN where estimated rows for REF
where changed from 2 to 1.
- A few test cases using explain extended had a change of 'filtered'.
This is because of the estimated rows are now closer to the
calculated selectivity.
- A very few test had a change of table order.
This is because the change of estimated rows from 2 to 1 or the small
cost change for REF
(main.subselect_sj_jcl6, main.group_by, main.dervied_cond_pushdown,
main.distinct, main.join_nested, main.order_by, main.join_cache)
- No key statistics and the estimated rows are now smaller which cased
estimated filtering to be lower.
(main.subselect_sj_mat)
- The number of total rows are halved.
(main.derived_cond_pushdown)
- Plans with 1 row changed to use RANGE instead of REF.
(main.group_min_max)
- ALL changed to REF
(main.key_diff)
- Key changed from ref + index_only to PRIMARY key for InnoDB, as
OPTIMIZER_ROW_LOOKUP_COST + OPTIMIZER_ROW_NEXT_FIND_COST is smaller than
OPTIMIZER_KEY_LOOKUP_COST + OPTIMIZER_KEY_NEXT_FIND_COST.
(main.join_outer_innodb)
- Cost changes printouts
(main.opt_trace*)
- Result order change
(innodb_gis.rtree)
Diffstat (limited to 'mysql-test/main/subselect_no_mat.result')
-rw-r--r-- | mysql-test/main/subselect_no_mat.result | 18 |
1 files changed, 9 insertions, 9 deletions
diff --git a/mysql-test/main/subselect_no_mat.result b/mysql-test/main/subselect_no_mat.result index ad5ead75ccb..12c72545f73 100644 --- a/mysql-test/main/subselect_no_mat.result +++ b/mysql-test/main/subselect_no_mat.result @@ -352,7 +352,7 @@ patient_uq clinic_uq explain extended select * from t6 where exists (select * from t7 where uq = clinic_uq); id select_type table type possible_keys key key_len ref rows filtered Extra 1 PRIMARY t7 index PRIMARY PRIMARY 4 NULL 2 100.00 Using index -1 PRIMARY t6 ref i1 i1 5 test.t7.uq 2 100.00 +1 PRIMARY t6 ref i1 i1 5 test.t7.uq 1 100.00 Warnings: Note 1276 Field or reference 'test.t6.clinic_uq' of SELECT #2 was resolved in SELECT #1 Note 1003 select `test`.`t6`.`patient_uq` AS `patient_uq`,`test`.`t6`.`clinic_uq` AS `clinic_uq` from `test`.`t7` join `test`.`t6` where `test`.`t6`.`clinic_uq` = `test`.`t7`.`uq` @@ -4411,7 +4411,7 @@ CREATE INDEX I2 ON t1 (b); EXPLAIN SELECT a,b FROM t1 WHERE b IN (SELECT a FROM t1); id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY t1 index I1 I1 2 NULL 2 Using where; Using index; LooseScan -1 PRIMARY t1 ref I2 I2 13 test.t1.a 2 Using index condition +1 PRIMARY t1 ref I2 I2 13 test.t1.a 1 Using index condition SELECT a,b FROM t1 WHERE b IN (SELECT a FROM t1); a b CREATE TABLE t2 (a VARCHAR(1), b VARCHAR(10)); @@ -4421,14 +4421,14 @@ CREATE INDEX I2 ON t2 (b); EXPLAIN SELECT a,b FROM t2 WHERE b IN (SELECT a FROM t2); id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY t2 index I1 I1 4 NULL 2 Using where; Using index; LooseScan -1 PRIMARY t2 ref I2 I2 13 test.t2.a 2 Using index condition +1 PRIMARY t2 ref I2 I2 13 test.t2.a 1 Using index condition SELECT a,b FROM t2 WHERE b IN (SELECT a FROM t2); a b EXPLAIN SELECT a,b FROM t1 WHERE b IN (SELECT a FROM t1 WHERE LENGTH(a)<500); id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY t1 index I1 I1 2 NULL 2 Using where; Using index; LooseScan -1 PRIMARY t1 ref I2 I2 13 test.t1.a 2 Using index condition +1 PRIMARY t1 ref I2 I2 13 test.t1.a 1 Using index condition SELECT a,b FROM t1 WHERE b IN (SELECT a FROM t1 WHERE LENGTH(a)<500); a b DROP TABLE t1,t2; @@ -6656,7 +6656,7 @@ SET @@optimizer_switch='semijoin=off,materialization=off,in_to_exists=on,subquer EXPLAIN SELECT * FROM t1 WHERE a IN (SELECT a AS field1 FROM t1 GROUP BY field1); id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY t1 index NULL a 4 NULL 2 Using where; Using index -2 DEPENDENT SUBQUERY t1 index_subquery a a 4 func 2 Using index +2 DEPENDENT SUBQUERY t1 index_subquery a a 4 func 1 Using index SELECT * FROM t1 WHERE a IN (SELECT a AS field1 FROM t1 GROUP BY field1); a 2009-01-01 @@ -6859,7 +6859,7 @@ FROM t1 AS alias1, t1 AS alias2, t1 AS alias3 WHERE alias1.a = alias2.a OR ('Moscow') IN ( SELECT a FROM t1 ); id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY alias1 index a a 19 NULL 11 Using where; Using index -1 PRIMARY alias2 ref a a 19 test.alias1.a 2 Using index +1 PRIMARY alias2 ref a a 19 test.alias1.a 1 Using index 1 PRIMARY alias3 index NULL a 19 NULL 11 Using index; Using join buffer (flat, BNL join) 2 SUBQUERY t1 index_subquery a a 19 const 1 Using index; Using where SELECT MAX( alias2.a ) @@ -7009,7 +7009,7 @@ WHERE SLEEP(0.1) OR c < 'p' OR b = ( SELECT MIN(b) FROM t2 ); id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY t1 system NULL NULL NULL NULL 1 1 PRIMARY t2 ALL b NULL NULL NULL 2 Using where -1 PRIMARY t3 ref d d 5 test.t2.b 2 Using index +1 PRIMARY t3 ref d d 5 test.t2.b 1 Using index 3 SUBQUERY NULL NULL NULL NULL NULL NULL NULL Select tables optimized away set @tmp_mdev410=@@global.userstat; set global userstat=on; @@ -7041,7 +7041,7 @@ EXPLAIN SELECT * FROM t1 WHERE EXISTS ( SELECT a FROM t1, t2 WHERE b = a GROUP B id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY NULL NULL NULL NULL NULL NULL NULL Impossible WHERE 2 SUBQUERY t1 range a a 5 NULL 2 Using where; Using index -2 SUBQUERY t2 ref b b 5 test.t1.a 2 Using index +2 SUBQUERY t2 ref b b 5 test.t1.a 1 Using index DROP TABLE t1,t2; # # MDEV-435: Expensive subqueries may be evaluated during optimization in merge_key_fields @@ -7074,7 +7074,7 @@ EXPLAIN SELECT * FROM t1 WHERE EXISTS ( SELECT a FROM t1, t2 WHERE b = a GROUP B id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY NULL NULL NULL NULL NULL NULL NULL Impossible WHERE 2 SUBQUERY t1 range a a 5 NULL 2 Using where; Using index -2 SUBQUERY t2 ref b b 5 test.t1.a 2 Using index +2 SUBQUERY t2 ref b b 5 test.t1.a 1 Using index DROP TABLE t1,t2; # # MDEV-5991: crash in Item_field::used_tables |