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MDEV-19834 Selectivity of an equality condition discounted twice

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When discounting selectivity of ref access, don't discount the
selectivity we've already discounted for range access.

The 10.1 version of the fix. Will need to adjust condition filtering
test results in 10.4
This commit is contained in:
Sergei Petrunia
2019-08-15 12:57:21 +03:00
parent 588e67956a
commit 1c75ad6eed
3 changed files with 67 additions and 6 deletions
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24
mysql-test/t/selectivity.test
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@ -1,4 +1,5 @@
--source include/have_stat_tables.inc
--source include/have_sequence.inc
--disable_warnings
drop table if exists t0,t1,t2,t3;
@ -1102,3 +1103,26 @@ set @@optimizer_use_condition_selectivity=@save_optimizer_use_condition_selectiv
drop table t1;
drop function f1;
--echo #
--echo # MDEV-19834 Selectivity of an equality condition discounted twice
--echo #
set @@optimizer_use_condition_selectivity=4;
set @@use_stat_tables='preferably';
create table t1 (a int, b int, key (b), key (a));
insert into t1
select (rand(1)*1000)/10, (rand(1001)*1000)/50 from seq_1_to_1000;
analyze table t1 ;
--echo # Check what info the optimizer has about selectivities
explain extended select * from t1 use index () where a in (17,51,5);
explain extended select * from t1 use index () where b=2;
--echo # Now, the equality is used for ref access, while the range condition
--echo # gives selectivity data
explain extended select * from t1 where a in (17,51,5) and b=2;
drop table t1;
set use_stat_tables= @save_use_stat_tables;
set optimizer_use_condition_selectivity=@save_optimizer_use_condition_selectivity;
--echo # End of 10.1 tests