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MDEV-17032: Estimates are higher for partitions of a table with @@use_stat_tables= PREFERABLY

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The problem here is EITS statistics does not calculate statistics for the partitions of the table.
So a temporary solution would be to not read EITS statistics for partitioned tables.

Also disabling reading of EITS for columns that participate in the partition list of a table.
This commit is contained in:
Varun Gupta
2018-12-07 02:12:22 +05:30
parent 12b1ba195c
commit 4886d14827
7 changed files with 235 additions and 9 deletions
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100
mysql-test/r/partition.result
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@@ -2645,3 +2645,103 @@ Warnings:
Note 1517 Duplicate partition name p2
DEALLOCATE PREPARE stmt;
DROP TABLE t1;
#
# MDEV-17032: Estimates are higher for partitions of a table with @@use_stat_tables= PREFERABLY
#
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 (
part_key int,
a int,
b int
) partition by list(part_key) (
partition p0 values in (0),
partition p1 values in (1),
partition p2 values in (2),
partition p3 values in (3),
partition p4 values in (4)
);
insert into t2
select mod(a,5), a/100, mod(a,5) from t1;
set @save_use_stat_tables= @@use_stat_tables;
set @save_optimizer_use_condition_selectivity=@@optimizer_use_condition_selectivity;
#
# Tests using stats provided by the storage engine
#
explain extended select * from t2 where part_key=1;
id select_type table type possible_keys key key_len ref rows filtered Extra
1 SIMPLE t2 ALL NULL NULL NULL NULL 200 100.00 Using where
Warnings:
Note 1003 select `test`.`t2`.`part_key` AS `part_key`,`test`.`t2`.`a` AS `a`,`test`.`t2`.`b` AS `b` from `test`.`t2` where (`test`.`t2`.`part_key` = 1)
explain partitions select * from t2 where part_key=1;
id select_type table partitions type possible_keys key key_len ref rows Extra
1 SIMPLE t2 p1 ALL NULL NULL NULL NULL 200 Using where
explain extended select * from t2 where part_key in (1,2);
id select_type table type possible_keys key key_len ref rows filtered Extra
1 SIMPLE t2 ALL NULL NULL NULL NULL 400 100.00 Using where
Warnings:
Note 1003 select `test`.`t2`.`part_key` AS `part_key`,`test`.`t2`.`a` AS `a`,`test`.`t2`.`b` AS `b` from `test`.`t2` where (`test`.`t2`.`part_key` in (1,2))
explain partitions select * from t2 where part_key in (1,2);
id select_type table partitions type possible_keys key key_len ref rows Extra
1 SIMPLE t2 p1,p2 ALL NULL NULL NULL NULL 400 Using where
explain extended select * from t2 where b=5;
id select_type table type possible_keys key key_len ref rows filtered Extra
1 SIMPLE t2 ALL NULL NULL NULL NULL 1000 100.00 Using where
Warnings:
Note 1003 select `test`.`t2`.`part_key` AS `part_key`,`test`.`t2`.`a` AS `a`,`test`.`t2`.`b` AS `b` from `test`.`t2` where (`test`.`t2`.`b` = 5)
explain partitions select * from t2 where b=5;
id select_type table partitions type possible_keys key key_len ref rows Extra
1 SIMPLE t2 p0,p1,p2,p3,p4 ALL NULL NULL NULL NULL 1000 Using where
explain extended select * from t2 partition(p0) where b=1;
id select_type table type possible_keys key key_len ref rows filtered Extra
1 SIMPLE t2 ALL NULL NULL NULL NULL 200 100.00 Using where
Warnings:
Note 1003 select `test`.`t2`.`part_key` AS `part_key`,`test`.`t2`.`a` AS `a`,`test`.`t2`.`b` AS `b` from `test`.`t2` PARTITION (`p0`) where (`test`.`t2`.`b` = 1)
set @save_histogram_size=@@histogram_size;
set @@histogram_size=100;
set @@use_stat_tables= PREFERABLY;
set @@optimizer_use_condition_selectivity=4;
analyze table t2;
Table Op Msg_type Msg_text
test.t2 analyze status Engine-independent statistics collected
test.t2 analyze status OK
#
# Tests using EITS
#
# filtered should be 100
explain extended select * from t2 where part_key=1;
id select_type table type possible_keys key key_len ref rows filtered Extra
1 SIMPLE t2 ALL NULL NULL NULL NULL 200 100.00 Using where
Warnings:
Note 1003 select `test`.`t2`.`part_key` AS `part_key`,`test`.`t2`.`a` AS `a`,`test`.`t2`.`b` AS `b` from `test`.`t2` where (`test`.`t2`.`part_key` = 1)
explain partitions select * from t2 where part_key=1;
id select_type table partitions type possible_keys key key_len ref rows Extra
1 SIMPLE t2 p1 ALL NULL NULL NULL NULL 200 Using where
# filtered should be 100
explain extended select * from t2 where part_key in (1,2);
id select_type table type possible_keys key key_len ref rows filtered Extra
1 SIMPLE t2 ALL NULL NULL NULL NULL 400 100.00 Using where
Warnings:
Note 1003 select `test`.`t2`.`part_key` AS `part_key`,`test`.`t2`.`a` AS `a`,`test`.`t2`.`b` AS `b` from `test`.`t2` where (`test`.`t2`.`part_key` in (1,2))
explain partitions select * from t2 where part_key in (1,2);
id select_type table partitions type possible_keys key key_len ref rows Extra
1 SIMPLE t2 p1,p2 ALL NULL NULL NULL NULL 400 Using where
explain extended select * from t2 where b=5;
id select_type table type possible_keys key key_len ref rows filtered Extra
1 SIMPLE t2 ALL NULL NULL NULL NULL 1000 19.80 Using where
Warnings:
Note 1003 select `test`.`t2`.`part_key` AS `part_key`,`test`.`t2`.`a` AS `a`,`test`.`t2`.`b` AS `b` from `test`.`t2` where (`test`.`t2`.`b` = 5)
explain partitions select * from t2 where b=5;
id select_type table partitions type possible_keys key key_len ref rows Extra
1 SIMPLE t2 p0,p1,p2,p3,p4 ALL NULL NULL NULL NULL 1000 Using where
explain extended select * from t2 partition(p0) where b=1;
id select_type table type possible_keys key key_len ref rows filtered Extra
1 SIMPLE t2 ALL NULL NULL NULL NULL 200 19.80 Using where
Warnings:
Note 1003 select `test`.`t2`.`part_key` AS `part_key`,`test`.`t2`.`a` AS `a`,`test`.`t2`.`b` AS `b` from `test`.`t2` PARTITION (`p0`) where (`test`.`t2`.`b` = 1)
set @@use_stat_tables= @save_use_stat_tables;
set @@optimizer_use_condition_selectivity= @save_optimizer_use_condition_selectivity;
set @@histogram_size= @save_histogram_size;
drop table t0,t1,t2;