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MDEV-5985: EITS: selectivity estimates look illogical for join and non-key equalities

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Part#1. 

table_cond_selectivity() should discount selectivity of table' 
conditions only when ity counts that selectivity to begin with. 

For non-ref-based access methods (ALL/range/index_merge/etc),
we start with sel=1.0 and hence do not need to discount any
selectivities.
This commit is contained in:
Sergey Petrunya
2014-06-10 12:25:16 +02:00
parent 349e31d5a7
commit aeb62282a2
3 changed files with 75 additions and 13 deletions
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21
mysql-test/t/selectivity_no_engine.test
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@ -189,6 +189,27 @@ select * from t1,t2 where t1.id = t2.t1_id and t2.f2='qux' and t2.f1='baz';
drop table t1,t2;
--echo #
--echo # MDEV-5985: EITS: selectivity estimates look illogical for join and non-key equalities
--echo #
create table t0(a int);
insert into t0 values (0),(1),(2),(3),(4),(5),(6),(7),(8),(9);
create table t1(a int);
insert into t1 select A.a + B.a* 10 + C.a * 100 from t0 A, t0 B, t0 C;
create table t2 as select * from t1;
set histogram_size=100;
set use_stat_tables='preferably';
set optimizer_use_condition_selectivity=4;
analyze table t1 persistent for all;
analyze table t2 persistent for all;
--echo # Filtered will be 4.95, 9.90
explain extended select * from t1 A, t2 B where A.a < 40 and B.a < 100;
--echo # Here, B.filtered should not become 100%:
explain extended select * from t1 A, t2 B where A.a < 40 and B.a < 100 and B.a=A.a;
drop table t0,t1,t2;
--echo #
--echo # End of the test file
--echo #