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MDEV-15306: Wrong/Unexpected result with the value optimizer_use_condition_selectivity set to 4

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Currently for selectivity calculation we perform range analysis for a column even when we don't have any statistics(EITS).
This makes less sense but is used to catch contradiction for WHERE condition.

So the solution is to not perform range analysis for selectivity calculation for columns that do not have statistics.
This commit is contained in:
Varun Gupta
2018-08-28 21:59:11 +05:30
parent 5fb251642e
commit a9c09c95bd
5 changed files with 152 additions and 11 deletions
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44
mysql-test/r/selectivity_innodb.result
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@ -789,9 +789,9 @@ set optimizer_use_condition_selectivity=3;
explain extended
select * from t1 where a < 1 and a > 7;
id select_type table type possible_keys key key_len ref rows filtered Extra
1 SIMPLE NULL NULL NULL NULL NULL NULL NULL NULL Impossible WHERE noticed after reading const tables
1 SIMPLE t1 ALL NULL NULL NULL NULL 8 100.00 Using where
Warnings:
Note 1003 select `test`.`t1`.`a` AS `a` from `test`.`t1` where 0
Note 1003 select `test`.`t1`.`a` AS `a` from `test`.`t1` where ((`test`.`t1`.`a` < 1) and (`test`.`t1`.`a` > 7))
select * from t1 where a < 1 and a > 7;
a
drop table t1;
@ -1604,6 +1604,46 @@ drop table t1,t0;
set histogram_size=@save_histogram_size;
set optimizer_use_condition_selectivity=@save_optimizer_use_condition_selectivity;
set use_stat_tables=@save_use_stat_tables;
#
# MDEV-15306: Wrong/Unexpected result with the value
# optimizer_use_condition_selectivity set to 4
#
CREATE TABLE t1 (a INT);
INSERT INTO t1 VALUES (1), (2), (3), (4), (5), (6), (7), (8), (9), (10);
CREATE FUNCTION f1() RETURNS INT DETERMINISTIC
BEGIN
SET @cnt := @cnt + 1;
RETURN 1;
END;|
set @save_optimizer_use_condition_selectivity=@@optimizer_use_condition_selectivity;
set @save_use_stat_tables= @@use_stat_tables;
set @@use_stat_tables='complementary';
set @@optimizer_use_condition_selectivity=4;
SET @cnt= 0;
SELECT * FROM t1 WHERE a = f1();
a
1
SELECT @cnt;
@cnt
1
set @@use_stat_tables='preferably';
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
SET @cnt := 0;
set @@optimizer_use_condition_selectivity=4;
SELECT * FROM t1 WHERE a = f1();
a
1
SELECT @cnt;
@cnt
2
alter table t1 force;
set @@use_stat_tables= @save_use_stat_tables;
set @@optimizer_use_condition_selectivity=@save_optimizer_use_condition_selectivity;
drop table t1;
drop function f1;
set optimizer_switch=@save_optimizer_switch_for_selectivity_test;
set @tmp_ust= @@use_stat_tables;
set @tmp_oucs= @@optimizer_use_condition_selectivity;