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Commit 42fea34d authored by Igor Babaev's avatar Igor Babaev
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MDEV-27262 Unexpected index intersection with full index scan for an index 

If when extracting a range condition for an index from the WHERE condition
Range Optimizer sees that the range condition covers the whole index then
such condition should be discarded because it cannot be used in any range
scan. In some cases Range Optimizer really does it, but there remained some
conditions for which it was not done. As a result the optimizer could
produce index merge plans with the full index scan for one of the indexes
participating in the index merge.
This could be observed in one of the test cases from index_merge1.inc
where a plan with index_merge_sort_union was produced and in the test case
reported for this bug where a plan with index_merge_sort_intersect was
produced. In both cases one of two index scans participating in index merge
ran over the whole index.
The patch slightly changes the original above mentioned test case from
index_merge1.inc to be able to produce an intended plan employing
index_merge_sort_union. The original query was left to show that index
merge is not used for it anymore.
It should be noted that for the plan with index_merge_sort_intersect could
be chosen for execution only due to a defect in the InnoDB code that
returns wrong estimates for the cardinality of big ranges.

This bug led to serious problems in 10.4+ where the optimization using
Rowid filters is employed (see mdev-26446).

Approved by Sergey Petrunia <sergey@mariadb.com>
parent b5cbe506
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Showing with 243 additions and 6 deletions
mysql-test/include/index_merge1.inc
View file @ 42fea34d
......@@ -150,12 +150,22 @@ explain select * from t0 where
(((key3 <7 and key7 < 6) or key5 < 2) and (key5 < 5 or key6 < 6));
explain select * from t0 where
((key3 <5 or key5 < 4) and (key1 < 4 or key2 < 4))
((key3 < 4 or key5 < 4) and (key1 < 4 or key2 < 4))
or
((key3 >=5 or key5 < 2) and (key5 < 5 or key6 < 6));
explain select * from t0 force index(i1, i2, i3, i4, i5, i6 ) where
((key3 <5 or key5 < 4) and (key1 < 4 or key2 < 4))
((key3 < 4 or key5 < 4) and (key1 < 4 or key2 < 4))
or
((key3 >=5 or key5 < 2) and (key5 < 5 or key6 < 6));
explain select * from t0 force index(i1, i2, i3, i4, i5, i6 ) where
((key3 < 5 or key5 < 4) and (key1 < 4 or key2 < 4))
or
((key3 >=5 or key5 < 2) and (key5 < 5 or key6 < 6));
explain select * from t0 force index(i1, i2, i3, i4, i5, i6 ) where
((key3 < 10 or key5 < 4) and (key1 < 4 or key2 < 4))
or
((key3 >=5 or key5 < 2) and (key5 < 5 or key6 < 6));
......
mysql-test/r/index_merge_myisam.result
View file @ 42fea34d
......@@ -173,17 +173,29 @@ or
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t0 index_merge i1,i2,i3,i5,i6,i7 i3,i5 4,4 NULL 11 Using sort_union(i3,i5); Using where
explain select * from t0 where
((key3 <5 or key5 < 4) and (key1 < 4 or key2 < 4))
((key3 < 4 or key5 < 4) and (key1 < 4 or key2 < 4))
or
((key3 >=5 or key5 < 2) and (key5 < 5 or key6 < 6));
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t0 ALL i1,i2,i3,i5,i6 NULL NULL NULL 1024 Using where
explain select * from t0 force index(i1, i2, i3, i4, i5, i6 ) where
((key3 <5 or key5 < 4) and (key1 < 4 or key2 < 4))
((key3 < 4 or key5 < 4) and (key1 < 4 or key2 < 4))
or
((key3 >=5 or key5 < 2) and (key5 < 5 or key6 < 6));
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t0 index_merge i1,i2,i3,i5,i6 i3,i5 4,4 NULL 1024 Using sort_union(i3,i5); Using where
explain select * from t0 force index(i1, i2, i3, i4, i5, i6 ) where
((key3 < 5 or key5 < 4) and (key1 < 4 or key2 < 4))
or
((key3 >=5 or key5 < 2) and (key5 < 5 or key6 < 6));
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t0 index_merge i1,i2,i3,i5,i6 i3,i5 0,4 NULL 1024 Using sort_union(i3,i5); Using where
1 SIMPLE t0 ALL i1,i2,i3,i5,i6 NULL NULL NULL 1024 Using where
explain select * from t0 force index(i1, i2, i3, i4, i5, i6 ) where
((key3 < 10 or key5 < 4) and (key1 < 4 or key2 < 4))
or
((key3 >=5 or key5 < 2) and (key5 < 5 or key6 < 6));
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t0 ALL i1,i2,i3,i5,i6 NULL NULL NULL 1024 Using where
select * from t0 where key1 < 5 or key8 < 4 order by key1;
key1 key2 key3 key4 key5 key6 key7 key8
1 1 1 1 1 1 1 1023
......
mysql-test/r/range_innodb.result
View file @ 42fea34d
......@@ -108,3 +108,108 @@ DROP TABLE t0,t1;
SET @@GLOBAL.debug_dbug = @saved_dbug;
set @@optimizer_switch= @optimizer_switch_save;
# End of 10.1 tests
#
# MDEV-27262: Index intersection with full scan over an index
#
CREATE TABLE t1 (
id int(10) unsigned NOT NULL AUTO_INCREMENT,
p char(32) DEFAULT NULL,
es tinyint(3) unsigned NOT NULL DEFAULT 0,
er tinyint(3) unsigned NOT NULL DEFAULT 0,
x mediumint(8) unsigned NOT NULL DEFAULT 0,
PRIMARY KEY (id),
INDEX es (es),
INDEX x (x),
INDEX er (er,x),
INDEX p (p)
) ENGINE=InnoDB DEFAULT CHARSET=latin1;
insert into t1(es,er) select 0, 1 from seq_1_to_45;
insert into t1(es,er) select 0, 2 from seq_1_to_49;
insert into t1(es,er) select 0, 3 from seq_1_to_951;
insert into t1(es,er) select 0, 3 from seq_1_to_1054;
insert into t1(es,er) select 0, 6 from seq_1_to_25;
insert into t1(es,er) select 0, 11 from seq_1_to_1;
insert into t1(es,er) select 1, 1 from seq_1_to_45;
insert into t1(es,er) select 1, 2 from seq_1_to_16;
insert into t1(es,er) select 1, 3 from seq_1_to_511;
insert into t1(es,er) select 1, 4 from seq_1_to_687;
insert into t1(es,er) select 1, 6 from seq_1_to_50;
insert into t1(es,er) select 1, 7 from seq_1_to_4;
insert into t1(es,er) select 1, 11 from seq_1_to_1;
insert into t1(es,er) select 2, 1 from seq_1_to_82;
insert into t1(es,er) select 2, 2 from seq_1_to_82;
insert into t1(es,er) select 2, 3 from seq_1_to_1626;
insert into t1(es,er) select 2, 4 from seq_1_to_977;
insert into t1(es,er) select 2, 6 from seq_1_to_33;
insert into t1(es,er) select 2, 11 from seq_1_to_1;
insert into t1(es,er) select 3, 1 from seq_1_to_245;
insert into t1(es,er) select 3, 2 from seq_1_to_81;
insert into t1(es,er) select 3, 3 from seq_1_to_852;
insert into t1(es,er) select 3, 4 from seq_1_to_2243;
insert into t1(es,er) select 3, 6 from seq_1_to_44;
insert into t1(es,er) select 3, 11 from seq_1_to_1;
insert into t1(es,er) select 4, 1 from seq_1_to_91;
insert into t1(es,er) select 4, 2 from seq_1_to_83;
insert into t1(es,er) select 4, 3 from seq_1_to_297;
insert into t1(es,er) select 4, 4 from seq_1_to_2456;
insert into t1(es,er) select 4, 6 from seq_1_to_19;
insert into t1(es,er) select 4, 11 from seq_1_to_1;
update t1 set p='foobar';
update t1 set x=0;
set @save_isp=@@innodb_stats_persistent;
set global innodb_stats_persistent= 1;
analyze table t1;
Table Op Msg_type Msg_text
test.t1 analyze status OK
set optimizer_switch='index_merge_sort_intersection=on';
SELECT * FROM t1
WHERE ((p = 'foo' AND er != 4) OR er = 4 ) AND (es >= 4) LIMIT 2;
id p es er x
14645 foobar 4 4 0
14646 foobar 4 4 0
EXPLAIN EXTENDED SELECT * FROM t1
WHERE ((p = 'foo' AND er != 4) OR er = 4 ) AND (es >= 4) LIMIT 2;
id select_type table type possible_keys key key_len ref rows filtered Extra
1 SIMPLE t1 range es,er,p es 1 NULL # 100.00 Using index condition; Using where
Warnings:
Note 1003 select `test`.`t1`.`id` AS `id`,`test`.`t1`.`p` AS `p`,`test`.`t1`.`es` AS `es`,`test`.`t1`.`er` AS `er`,`test`.`t1`.`x` AS `x` from `test`.`t1` where (`test`.`t1`.`p` = 'foo' and `test`.`t1`.`er` <> 4 or `test`.`t1`.`er` = 4) and `test`.`t1`.`es` >= 4 limit 2
set optimizer_switch='index_merge_sort_intersection=off';
SELECT * FROM t1
WHERE ((p = 'foo' AND er != 4) OR er = 4 ) AND (es >= 4) LIMIT 2;
id p es er x
14645 foobar 4 4 0
14646 foobar 4 4 0
EXPLAIN EXTENDED SELECT * FROM t1
WHERE ((p = 'foo' AND er != 4) OR er = 4 ) AND (es >= 4) LIMIT 2;
id select_type table type possible_keys key key_len ref rows filtered Extra
1 SIMPLE t1 range es,er,p es 1 NULL # 100.00 Using index condition; Using where
Warnings:
Note 1003 select `test`.`t1`.`id` AS `id`,`test`.`t1`.`p` AS `p`,`test`.`t1`.`es` AS `es`,`test`.`t1`.`er` AS `er`,`test`.`t1`.`x` AS `x` from `test`.`t1` where (`test`.`t1`.`p` = 'foo' and `test`.`t1`.`er` <> 4 or `test`.`t1`.`er` = 4) and `test`.`t1`.`es` >= 4 limit 2
set optimizer_switch='index_merge_sort_intersection=on';
SELECT * FROM t1
WHERE ((p = 'foo' AND er < 6) OR er >=2 ) AND (es >= 4) LIMIT 2;
id p es er x
14007 foobar 4 2 0
14008 foobar 4 2 0
EXPLAIN EXTENDED SELECT * FROM t1
WHERE ((p = 'foo' AND er < 6) OR er >=2 ) AND (es >= 4) LIMIT 2;
id select_type table type possible_keys key key_len ref rows filtered Extra
1 SIMPLE t1 range es,er,p es 1 NULL # 100.00 Using index condition; Using where
Warnings:
Note 1003 select `test`.`t1`.`id` AS `id`,`test`.`t1`.`p` AS `p`,`test`.`t1`.`es` AS `es`,`test`.`t1`.`er` AS `er`,`test`.`t1`.`x` AS `x` from `test`.`t1` where (`test`.`t1`.`p` = 'foo' and `test`.`t1`.`er` < 6 or `test`.`t1`.`er` >= 2) and `test`.`t1`.`es` >= 4 limit 2
set optimizer_switch='index_merge_sort_intersection=off';
SELECT * FROM t1
WHERE ((p = 'foo' AND er < 6) OR er >=2 ) AND (es >= 4) LIMIT 2;
id p es er x
14007 foobar 4 2 0
14008 foobar 4 2 0
EXPLAIN EXTENDED SELECT * FROM t1
WHERE ((p = 'foo' AND er < 6) OR er >=2 ) AND (es >= 4) LIMIT 2;
id select_type table type possible_keys key key_len ref rows filtered Extra
1 SIMPLE t1 range es,er,p es 1 NULL # 100.00 Using index condition; Using where
Warnings:
Note 1003 select `test`.`t1`.`id` AS `id`,`test`.`t1`.`p` AS `p`,`test`.`t1`.`es` AS `es`,`test`.`t1`.`er` AS `er`,`test`.`t1`.`x` AS `x` from `test`.`t1` where (`test`.`t1`.`p` = 'foo' and `test`.`t1`.`er` < 6 or `test`.`t1`.`er` >= 2) and `test`.`t1`.`es` >= 4 limit 2
set optimizer_switch='index_merge_sort_intersection=default';
set global innodb_stats_persistent= @save_isp;
DROP TABLE t1;
# End of 10.2 tests
mysql-test/t/range_innodb.test
View file @ 42fea34d
......@@ -116,3 +116,96 @@ SET @@GLOBAL.debug_dbug = @saved_dbug;
set @@optimizer_switch= @optimizer_switch_save;
--echo # End of 10.1 tests
--echo #
--echo # MDEV-27262: Index intersection with full scan over an index
--echo #
--source include/have_sequence.inc
CREATE TABLE t1 (
id int(10) unsigned NOT NULL AUTO_INCREMENT,
p char(32) DEFAULT NULL,
es tinyint(3) unsigned NOT NULL DEFAULT 0,
er tinyint(3) unsigned NOT NULL DEFAULT 0,
x mediumint(8) unsigned NOT NULL DEFAULT 0,
PRIMARY KEY (id),
INDEX es (es),
INDEX x (x),
INDEX er (er,x),
INDEX p (p)
) ENGINE=InnoDB DEFAULT CHARSET=latin1;
insert into t1(es,er) select 0, 1 from seq_1_to_45;
insert into t1(es,er) select 0, 2 from seq_1_to_49;
insert into t1(es,er) select 0, 3 from seq_1_to_951;
insert into t1(es,er) select 0, 3 from seq_1_to_1054;
insert into t1(es,er) select 0, 6 from seq_1_to_25;
insert into t1(es,er) select 0, 11 from seq_1_to_1;
insert into t1(es,er) select 1, 1 from seq_1_to_45;
insert into t1(es,er) select 1, 2 from seq_1_to_16;
insert into t1(es,er) select 1, 3 from seq_1_to_511;
insert into t1(es,er) select 1, 4 from seq_1_to_687;
insert into t1(es,er) select 1, 6 from seq_1_to_50;
insert into t1(es,er) select 1, 7 from seq_1_to_4;
insert into t1(es,er) select 1, 11 from seq_1_to_1;
insert into t1(es,er) select 2, 1 from seq_1_to_82;
insert into t1(es,er) select 2, 2 from seq_1_to_82;
insert into t1(es,er) select 2, 3 from seq_1_to_1626;
insert into t1(es,er) select 2, 4 from seq_1_to_977;
insert into t1(es,er) select 2, 6 from seq_1_to_33;
insert into t1(es,er) select 2, 11 from seq_1_to_1;
insert into t1(es,er) select 3, 1 from seq_1_to_245;
insert into t1(es,er) select 3, 2 from seq_1_to_81;
insert into t1(es,er) select 3, 3 from seq_1_to_852;
insert into t1(es,er) select 3, 4 from seq_1_to_2243;
insert into t1(es,er) select 3, 6 from seq_1_to_44;
insert into t1(es,er) select 3, 11 from seq_1_to_1;
insert into t1(es,er) select 4, 1 from seq_1_to_91;
insert into t1(es,er) select 4, 2 from seq_1_to_83;
insert into t1(es,er) select 4, 3 from seq_1_to_297;
insert into t1(es,er) select 4, 4 from seq_1_to_2456;
insert into t1(es,er) select 4, 6 from seq_1_to_19;
insert into t1(es,er) select 4, 11 from seq_1_to_1;
update t1 set p='foobar';
update t1 set x=0;
set @save_isp=@@innodb_stats_persistent;
set global innodb_stats_persistent= 1;
analyze table t1;
let $q=
SELECT * FROM t1
WHERE ((p = 'foo' AND er != 4) OR er = 4 ) AND (es >= 4) LIMIT 2;
set optimizer_switch='index_merge_sort_intersection=on';
eval $q;
--replace_column 9 #
eval EXPLAIN EXTENDED $q;
set optimizer_switch='index_merge_sort_intersection=off';
# execution of $q and explain for it led to an assertion failure in 10.4
# (with the optimizer switch rowid_filter set to 'on')
eval $q;
--replace_column 9 #
eval EXPLAIN EXTENDED $q;
let $q=
SELECT * FROM t1
WHERE ((p = 'foo' AND er < 6) OR er >=2 ) AND (es >= 4) LIMIT 2;
set optimizer_switch='index_merge_sort_intersection=on';
eval $q;
--replace_column 9 #
eval EXPLAIN EXTENDED $q;
set optimizer_switch='index_merge_sort_intersection=off';
eval $q;
--replace_column 9 #
eval EXPLAIN EXTENDED $q;
set optimizer_switch='index_merge_sort_intersection=default';
set global innodb_stats_persistent= @save_isp;
DROP TABLE t1;
--echo # End of 10.2 tests
sql/opt_range.cc
View file @ 42fea34d
......@@ -9329,7 +9329,7 @@ key_or(RANGE_OPT_PARAM *param, SEL_ARG *key1,SEL_ARG *key2)
uint max_part_no= MY_MAX(key1->max_part_no, key2->max_part_no);
for (key2=key2->first(); key2; )
for (key2=key2->first(); ; )
{
/*
key1 consists of one or more ranges. tmp is the range currently
......@@ -9343,6 +9343,16 @@ key_or(RANGE_OPT_PARAM *param, SEL_ARG *key1,SEL_ARG *key2)
^
tmp
*/
if (key1->min_flag & NO_MIN_RANGE &&
key1->max_flag & NO_MAX_RANGE)
{
if (key1->maybe_flag)
return new SEL_ARG(SEL_ARG::MAYBE_KEY);
return 0; // Always true OR
}
if (!key2)
break;
SEL_ARG *tmp=key1->find_range(key2);
/*
......@@ -9413,6 +9423,13 @@ key_or(RANGE_OPT_PARAM *param, SEL_ARG *key1,SEL_ARG *key2)
key2->copy_min(tmp);
if (!(key1=key1->tree_delete(tmp)))
{ // Only one key in tree
if (key2->min_flag & NO_MIN_RANGE &&
key2->max_flag & NO_MAX_RANGE)
{
if (key2->maybe_flag)
return new SEL_ARG(SEL_ARG::MAYBE_KEY);
return 0; // Always true OR
}
key1=key2;
key1->make_root();
key2=key2_next;
......
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