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MDEV-20109: Optimizer ignores distinct key created for materialized...

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(Backported to 10.3, addressed review input)

Sj_materialization_picker::check_qep(): fix error in cost/fanout
calculations:
- for each join prefix, add #prefix_rows / TIME_FOR_COMPARE to the cost,
  like best_extension_by_limited_search does
- Remove the fanout produced by the subquery tables.
- Also take into account join condition selectivity

optimize_wo_join_buffering() (used by LooseScan and FirstMatch)
- also add #prefix_rows / TIME_FOR_COMPARE to the cost of each prefix.
- Also take into account join condition selectivity
This commit is contained in:
Sergei Petrunia 2019-08-29 15:37:49 +03:00
commit ef76f81c98
27 changed files with 392 additions and 295 deletions
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20
mysql-test/main/subselect3_jcl6.result
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@ -1149,8 +1149,8 @@ create table t3 (a int);
insert into t3 select A.a + 10*B.a from t0 A, t0 B;
explain select * from t3 where a in (select kp1 from t1 where kp1<20);
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY t1 range kp1 kp1 5 NULL 48 Using where; Using index; LooseScan
1 PRIMARY t3 ALL NULL NULL NULL NULL 100 Using where; Using join buffer (flat, BNL join)
1 PRIMARY t3 ALL NULL NULL NULL NULL 100 Using where
1 PRIMARY t1 ref kp1 kp1 5 test.t3.a 1 Using index; FirstMatch(t3)
create table t4 (pk int primary key);
insert into t4 select a from t3;
explain select * from t3 where a in (select t1.kp1 from t1,t4 where kp1<20
@ -1286,12 +1286,12 @@ insert into t1 select A.a, B.a, 'filler' from t0 A, t0 B;
create table t2 as select * from t1;
explain select * from t2 where a in (select b from t1 where a=3);
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY t1 ref a a 5 const 8 Using index; LooseScan
1 PRIMARY t2 ALL NULL NULL NULL NULL 100 Using where; Using join buffer (flat, BNL join)
1 PRIMARY t2 ALL NULL NULL NULL NULL 100 Using where
1 PRIMARY t1 ref a a 10 const,test.t2.a 1 Using index; FirstMatch(t2)
explain select * from t2 where (b,a) in (select a,b from t1 where a=3);
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY t1 ref a a 5 const 8 Using index; LooseScan
1 PRIMARY t2 ALL NULL NULL NULL NULL 100 Using where; Using join buffer (flat, BNL join)
1 PRIMARY t2 ALL NULL NULL NULL NULL 100 Using where
1 PRIMARY t1 ref a a 10 const,test.t2.a 1 Using index; FirstMatch(t2)
drop table t1,t2;
set @@optimizer_switch=@save_optimizer_switch;
create table t1 (a int, b int);
@ -1348,10 +1348,10 @@ create table t2 as select a as a, a as b from t0 where a < 3;
insert into t2 select * from t2;
explain select * from t1 where (a,b,c) in (select X.a, Y.a, Z.a from t2 X, t2 Y, t2 Z where X.b=33);
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY t1 ALL NULL NULL NULL NULL 3
1 PRIMARY X ALL NULL NULL NULL NULL 6 Using where; Using join buffer (flat, BNL join)
1 PRIMARY Y ALL NULL NULL NULL NULL 6 Using where; Using join buffer (incremental, BNL join)
1 PRIMARY Z ALL NULL NULL NULL NULL 6 Using where; FirstMatch(t1); Using join buffer (incremental, BNL join)
1 PRIMARY t1 ALL NULL NULL NULL NULL 3 Using where
1 PRIMARY X hash_ALL NULL #hash#$hj 5 test.t1.a 6 Using where; Start temporary; Using join buffer (flat, BNLH join)
1 PRIMARY Y hash_ALL NULL #hash#$hj 5 test.t1.b 6 Using where; Using join buffer (incremental, BNLH join)
1 PRIMARY Z hash_ALL NULL #hash#$hj 5 test.t1.c 6 Using where; End temporary; Using join buffer (incremental, BNLH join)
drop table t0,t1,t2;
set @@optimizer_switch=@save_optimizer_switch;