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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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34
mysql-test/r/selectivity_no_engine.result
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@ -243,6 +243,40 @@ foo 2011-04-12 05:18:08 foo baz qux
bar 2013-09-19 11:37:03 bar baz qux
drop table t1,t2;
#
# MDEV-5985: EITS: selectivity estimates look illogical for join and non-key equalities
#
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;
Table Op Msg_type Msg_text
test.t1 analyze status Engine-independent statistics collected
test.t1 analyze status OK
analyze table t2 persistent for all;
Table Op Msg_type Msg_text
test.t2 analyze status Engine-independent statistics collected
test.t2 analyze status OK
# Filtered will be 4.95, 9.90
explain extended select * from t1 A, t2 B where A.a < 40 and B.a < 100;
id select_type table type possible_keys key key_len ref rows filtered Extra
1 SIMPLE A ALL NULL NULL NULL NULL 1000 4.95 Using where
1 SIMPLE B ALL NULL NULL NULL NULL 1000 9.90 Using where; Using join buffer (flat, BNL join)
Warnings:
Note 1003 select `test`.`A`.`a` AS `a`,`test`.`B`.`a` AS `a` from `test`.`t1` `A` join `test`.`t2` `B` where ((`test`.`A`.`a` < 40) and (`test`.`B`.`a` < 100))
# 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;
id select_type table type possible_keys key key_len ref rows filtered Extra
1 SIMPLE A ALL NULL NULL NULL NULL 1000 4.95 Using where
1 SIMPLE B ALL NULL NULL NULL NULL 1000 4.95 Using where; Using join buffer (flat, BNL join)
Warnings:
Note 1003 select `test`.`A`.`a` AS `a`,`test`.`B`.`a` AS `a` from `test`.`t1` `A` join `test`.`t2` `B` where ((`test`.`B`.`a` = `test`.`A`.`a`) and (`test`.`A`.`a` < 40) and (`test`.`A`.`a` < 100))
drop table t0,t1,t2;
#
# End of the test file
#
set use_stat_tables= @save_use_stat_tables;