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Fixed bug mdev-7992.

Browse Source 
'Not exists' optimization can be used for nested outer joins
only if IS NULL predicate from the WHERE condition is activated.
So we have to check that all guards that wrap this predicate
are in the 'open' state.
This patch supports usage of 'Not exists' optimization for any
outer join, no matter how it's nested in other outer joins.

This patch is also considered as a proper fix for bugs
#49322/#58490 and LP #817360.
This commit is contained in:
Igor Babaev
2017-02-24 00:10:08 -08:00
parent bdb672fe96
commit ac78927aef
4 changed files with 294 additions and 40 deletions
Download Patch File Download Diff File Expand all files Collapse all files

95
mysql-test/r/join_nested.result
View File

@ -1870,4 +1870,99 @@ f4
NULL
NULL
DROP TABLE t1,t2,t3,t4,t5;
#
# MDEV-7992: Nested left joins + 'not exists' optimization
#
CREATE TABLE t1(
K1 INT PRIMARY KEY,
Name VARCHAR(15)
);
INSERT INTO t1 VALUES
(1,'T1Row1'), (2,'T1Row2');
CREATE TABLE t2(
K2 INT PRIMARY KEY,
K1r INT,
rowTimestamp DATETIME,
Event VARCHAR(15)
);
INSERT INTO t2 VALUES
(1, 1, '2015-04-13 10:42:11' ,'T1Row1Event1'),
(2, 1, '2015-04-13 10:42:12' ,'T1Row1Event2'),
(3, 1, '2015-04-13 10:42:12' ,'T1Row1Event3');
SELECT t1a.*, t2a.*,
t2i.K2 AS K2B, t2i.K1r AS K1rB,
t2i.rowTimestamp AS rowTimestampB, t2i.Event AS EventB
FROM
t1 t1a JOIN t2 t2a ON t2a.K1r = t1a.K1
LEFT JOIN
( t1 t1i LEFT JOIN t2 t2i ON t2i.K1r = t1i.K1)
ON (t1i.K1 = 1) AND
(((t2i.K1r = t1a.K1 AND t2i.rowTimestamp > t2a.rowTimestamp ) OR
(t2i.rowTimestamp = t2a.rowTimestamp AND t2i.K2 > t2a.K2))
OR (t2i.K2 IS NULL))
WHERE
t2a.K1r = 1 AND t2i.K2 IS NULL;
K1 Name K2 K1r rowTimestamp Event K2B K1rB rowTimestampB EventB
1 T1Row1 3 1 2015-04-13 10:42:12 T1Row1Event3 NULL NULL NULL NULL
EXPLAIN EXTENDED SELECT t1a.*, t2a.*,
t2i.K2 AS K2B, t2i.K1r AS K1rB,
t2i.rowTimestamp AS rowTimestampB, t2i.Event AS EventB
FROM
t1 t1a JOIN t2 t2a ON t2a.K1r = t1a.K1
LEFT JOIN
( t1 t1i LEFT JOIN t2 t2i ON t2i.K1r = t1i.K1)
ON (t1i.K1 = 1) AND
(((t2i.K1r = t1a.K1 AND t2i.rowTimestamp > t2a.rowTimestamp ) OR
(t2i.rowTimestamp = t2a.rowTimestamp AND t2i.K2 > t2a.K2))
OR (t2i.K2 IS NULL))
WHERE
t2a.K1r = 1 AND t2i.K2 IS NULL;
id select_type table type possible_keys key key_len ref rows filtered Extra
1 SIMPLE t1a const PRIMARY PRIMARY 4 const 1 100.00
1 SIMPLE t2a ALL NULL NULL NULL NULL 3 100.00 Using where
1 SIMPLE t1i const PRIMARY PRIMARY 4 const 1 100.00 Using index
1 SIMPLE t2i ALL NULL NULL NULL NULL 3 100.00 Using where; Not exists
Warnings:
Note 1003 select 1 AS `K1`,'T1Row1' AS `Name`,`test`.`t2a`.`K2` AS `K2`,`test`.`t2a`.`K1r` AS `K1r`,`test`.`t2a`.`rowTimestamp` AS `rowTimestamp`,`test`.`t2a`.`Event` AS `Event`,`test`.`t2i`.`K2` AS `K2B`,`test`.`t2i`.`K1r` AS `K1rB`,`test`.`t2i`.`rowTimestamp` AS `rowTimestampB`,`test`.`t2i`.`Event` AS `EventB` from `test`.`t1` `t1a` join `test`.`t2` `t2a` left join (`test`.`t1` `t1i` left join `test`.`t2` `t2i` on((`test`.`t2i`.`K1r` = 1))) on(((`test`.`t1i`.`K1` = 1) and (((`test`.`t2i`.`K1r` = 1) and (`test`.`t2i`.`rowTimestamp` > `test`.`t2a`.`rowTimestamp`)) or ((`test`.`t2i`.`rowTimestamp` = `test`.`t2a`.`rowTimestamp`) and (`test`.`t2i`.`K2` > `test`.`t2a`.`K2`)) or isnull(`test`.`t2i`.`K2`)))) where ((`test`.`t2a`.`K1r` = 1) and isnull(`test`.`t2i`.`K2`))
CREATE VIEW v1 AS
SELECT t2i.*
FROM t1 as t1i LEFT JOIN t2 as t2i ON t2i.K1r = t1i.K1
WHERE t1i.K1 = 1 ;
SELECT
t1a.*, t2a.*, t2b.K2 as K2B, t2b.K1r as K1rB,
t2b.rowTimestamp as rowTimestampB, t2b.Event as EventB
FROM
t1 as t1a JOIN t2 as t2a ON t2a.K1r = t1a.K1
LEFT JOIN
v1 as t2b
ON ((t2b.K1r = t1a.K1 AND t2b.rowTimestamp > t2a.rowTimestamp) OR
(t2b.rowTimestamp = t2a.rowTimestamp AND t2b.K2 > t2a.K2))
OR (t2b.K2 IS NULL)
WHERE
t1a.K1 = 1 AND
t2b.K2 IS NULL;
K1 Name K2 K1r rowTimestamp Event K2B K1rB rowTimestampB EventB
1 T1Row1 3 1 2015-04-13 10:42:12 T1Row1Event3 NULL NULL NULL NULL
EXPLAIN EXTENDED SELECT
t1a.*, t2a.*, t2b.K2 as K2B, t2b.K1r as K1rB,
t2b.rowTimestamp as rowTimestampB, t2b.Event as EventB
FROM
t1 as t1a JOIN t2 as t2a ON t2a.K1r = t1a.K1
LEFT JOIN
v1 as t2b
ON ((t2b.K1r = t1a.K1 AND t2b.rowTimestamp > t2a.rowTimestamp) OR
(t2b.rowTimestamp = t2a.rowTimestamp AND t2b.K2 > t2a.K2))
OR (t2b.K2 IS NULL)
WHERE
t1a.K1 = 1 AND
t2b.K2 IS NULL;
id select_type table type possible_keys key key_len ref rows filtered Extra
1 SIMPLE t1a const PRIMARY PRIMARY 4 const 1 100.00
1 SIMPLE t2a ALL NULL NULL NULL NULL 3 100.00 Using where
1 SIMPLE t1i const PRIMARY PRIMARY 4 const 1 100.00 Using index
1 SIMPLE t2i ALL NULL NULL NULL NULL 3 100.00 Using where; Not exists
Warnings:
Note 1003 select 1 AS `K1`,'T1Row1' AS `Name`,`t2a`.`K2` AS `K2`,`t2a`.`K1r` AS `K1r`,`t2a`.`rowTimestamp` AS `rowTimestamp`,`t2a`.`Event` AS `Event`,`test`.`t2i`.`K2` AS `K2B`,`test`.`t2i`.`K1r` AS `K1rB`,`test`.`t2i`.`rowTimestamp` AS `rowTimestampB`,`test`.`t2i`.`Event` AS `EventB` from `test`.`t1` `t1a` join `test`.`t2` `t2a` left join (`test`.`t1` `t1i` left join `test`.`t2` `t2i` on((`test`.`t2i`.`K1r` = 1))) on(((`test`.`t1i`.`K1` = 1) and (((`test`.`t2i`.`K1r` = 1) and (`test`.`t2i`.`rowTimestamp` > `t2a`.`rowTimestamp`)) or ((`test`.`t2i`.`rowTimestamp` = `t2a`.`rowTimestamp`) and (`test`.`t2i`.`K2` > `t2a`.`K2`)) or isnull(`test`.`t2i`.`K2`)))) where ((`t2a`.`K1r` = 1) and isnull(`test`.`t2i`.`K2`))
DROP VIEW v1;
DROP TABLE t1,t2;
set optimizer_search_depth= @tmp_mdev621;

95
mysql-test/r/join_nested_jcl6.result
View File

@ -1881,6 +1881,101 @@ f4
NULL
NULL
DROP TABLE t1,t2,t3,t4,t5;
#
# MDEV-7992: Nested left joins + 'not exists' optimization
#
CREATE TABLE t1(
K1 INT PRIMARY KEY,
Name VARCHAR(15)
);
INSERT INTO t1 VALUES
(1,'T1Row1'), (2,'T1Row2');
CREATE TABLE t2(
K2 INT PRIMARY KEY,
K1r INT,
rowTimestamp DATETIME,
Event VARCHAR(15)
);
INSERT INTO t2 VALUES
(1, 1, '2015-04-13 10:42:11' ,'T1Row1Event1'),
(2, 1, '2015-04-13 10:42:12' ,'T1Row1Event2'),
(3, 1, '2015-04-13 10:42:12' ,'T1Row1Event3');
SELECT t1a.*, t2a.*,
t2i.K2 AS K2B, t2i.K1r AS K1rB,
t2i.rowTimestamp AS rowTimestampB, t2i.Event AS EventB
FROM
t1 t1a JOIN t2 t2a ON t2a.K1r = t1a.K1
LEFT JOIN
( t1 t1i LEFT JOIN t2 t2i ON t2i.K1r = t1i.K1)
ON (t1i.K1 = 1) AND
(((t2i.K1r = t1a.K1 AND t2i.rowTimestamp > t2a.rowTimestamp ) OR
(t2i.rowTimestamp = t2a.rowTimestamp AND t2i.K2 > t2a.K2))
OR (t2i.K2 IS NULL))
WHERE
t2a.K1r = 1 AND t2i.K2 IS NULL;
K1 Name K2 K1r rowTimestamp Event K2B K1rB rowTimestampB EventB
1 T1Row1 3 1 2015-04-13 10:42:12 T1Row1Event3 NULL NULL NULL NULL
EXPLAIN EXTENDED SELECT t1a.*, t2a.*,
t2i.K2 AS K2B, t2i.K1r AS K1rB,
t2i.rowTimestamp AS rowTimestampB, t2i.Event AS EventB
FROM
t1 t1a JOIN t2 t2a ON t2a.K1r = t1a.K1
LEFT JOIN
( t1 t1i LEFT JOIN t2 t2i ON t2i.K1r = t1i.K1)
ON (t1i.K1 = 1) AND
(((t2i.K1r = t1a.K1 AND t2i.rowTimestamp > t2a.rowTimestamp ) OR
(t2i.rowTimestamp = t2a.rowTimestamp AND t2i.K2 > t2a.K2))
OR (t2i.K2 IS NULL))
WHERE
t2a.K1r = 1 AND t2i.K2 IS NULL;
id select_type table type possible_keys key key_len ref rows filtered Extra
1 SIMPLE t1a const PRIMARY PRIMARY 4 const 1 100.00
1 SIMPLE t2a ALL NULL NULL NULL NULL 3 100.00 Using where
1 SIMPLE t1i const PRIMARY PRIMARY 4 const 1 100.00 Using index
1 SIMPLE t2i ALL NULL NULL NULL NULL 3 100.00 Using where; Not exists
Warnings:
Note 1003 select 1 AS `K1`,'T1Row1' AS `Name`,`test`.`t2a`.`K2` AS `K2`,`test`.`t2a`.`K1r` AS `K1r`,`test`.`t2a`.`rowTimestamp` AS `rowTimestamp`,`test`.`t2a`.`Event` AS `Event`,`test`.`t2i`.`K2` AS `K2B`,`test`.`t2i`.`K1r` AS `K1rB`,`test`.`t2i`.`rowTimestamp` AS `rowTimestampB`,`test`.`t2i`.`Event` AS `EventB` from `test`.`t1` `t1a` join `test`.`t2` `t2a` left join (`test`.`t1` `t1i` left join `test`.`t2` `t2i` on((`test`.`t2i`.`K1r` = 1))) on(((`test`.`t1i`.`K1` = 1) and (((`test`.`t2i`.`K1r` = 1) and (`test`.`t2i`.`rowTimestamp` > `test`.`t2a`.`rowTimestamp`)) or ((`test`.`t2i`.`rowTimestamp` = `test`.`t2a`.`rowTimestamp`) and (`test`.`t2i`.`K2` > `test`.`t2a`.`K2`)) or isnull(`test`.`t2i`.`K2`)))) where ((`test`.`t2a`.`K1r` = 1) and isnull(`test`.`t2i`.`K2`))
CREATE VIEW v1 AS
SELECT t2i.*
FROM t1 as t1i LEFT JOIN t2 as t2i ON t2i.K1r = t1i.K1
WHERE t1i.K1 = 1 ;
SELECT
t1a.*, t2a.*, t2b.K2 as K2B, t2b.K1r as K1rB,
t2b.rowTimestamp as rowTimestampB, t2b.Event as EventB
FROM
t1 as t1a JOIN t2 as t2a ON t2a.K1r = t1a.K1
LEFT JOIN
v1 as t2b
ON ((t2b.K1r = t1a.K1 AND t2b.rowTimestamp > t2a.rowTimestamp) OR
(t2b.rowTimestamp = t2a.rowTimestamp AND t2b.K2 > t2a.K2))
OR (t2b.K2 IS NULL)
WHERE
t1a.K1 = 1 AND
t2b.K2 IS NULL;
K1 Name K2 K1r rowTimestamp Event K2B K1rB rowTimestampB EventB
1 T1Row1 3 1 2015-04-13 10:42:12 T1Row1Event3 NULL NULL NULL NULL
EXPLAIN EXTENDED SELECT
t1a.*, t2a.*, t2b.K2 as K2B, t2b.K1r as K1rB,
t2b.rowTimestamp as rowTimestampB, t2b.Event as EventB
FROM
t1 as t1a JOIN t2 as t2a ON t2a.K1r = t1a.K1
LEFT JOIN
v1 as t2b
ON ((t2b.K1r = t1a.K1 AND t2b.rowTimestamp > t2a.rowTimestamp) OR
(t2b.rowTimestamp = t2a.rowTimestamp AND t2b.K2 > t2a.K2))
OR (t2b.K2 IS NULL)
WHERE
t1a.K1 = 1 AND
t2b.K2 IS NULL;
id select_type table type possible_keys key key_len ref rows filtered Extra
1 SIMPLE t1a const PRIMARY PRIMARY 4 const 1 100.00
1 SIMPLE t2a ALL NULL NULL NULL NULL 3 100.00 Using where
1 SIMPLE t1i const PRIMARY PRIMARY 4 const 1 100.00 Using index
1 SIMPLE t2i ALL NULL NULL NULL NULL 3 100.00 Using where; Not exists
Warnings:
Note 1003 select 1 AS `K1`,'T1Row1' AS `Name`,`t2a`.`K2` AS `K2`,`t2a`.`K1r` AS `K1r`,`t2a`.`rowTimestamp` AS `rowTimestamp`,`t2a`.`Event` AS `Event`,`test`.`t2i`.`K2` AS `K2B`,`test`.`t2i`.`K1r` AS `K1rB`,`test`.`t2i`.`rowTimestamp` AS `rowTimestampB`,`test`.`t2i`.`Event` AS `EventB` from `test`.`t1` `t1a` join `test`.`t2` `t2a` left join (`test`.`t1` `t1i` left join `test`.`t2` `t2i` on((`test`.`t2i`.`K1r` = 1))) on(((`test`.`t1i`.`K1` = 1) and (((`test`.`t2i`.`K1r` = 1) and (`test`.`t2i`.`rowTimestamp` > `t2a`.`rowTimestamp`)) or ((`test`.`t2i`.`rowTimestamp` = `t2a`.`rowTimestamp`) and (`test`.`t2i`.`K2` > `t2a`.`K2`)) or isnull(`test`.`t2i`.`K2`)))) where ((`t2a`.`K1r` = 1) and isnull(`test`.`t2i`.`K2`))
DROP VIEW v1;
DROP TABLE t1,t2;
set optimizer_search_depth= @tmp_mdev621;
CREATE TABLE t5 (a int, b int, c int, PRIMARY KEY(a), KEY b_i (b));
CREATE TABLE t6 (a int, b int, c int, PRIMARY KEY(a), KEY b_i (b));

71
mysql-test/t/join_nested.test
View File

@ -1309,5 +1309,74 @@ LEFT JOIN t4 AS alias5
JOIN t5 ON alias5.f5
ON alias2.f3 ON alias1.f2;
DROP TABLE t1,t2,t3,t4,t5;
set optimizer_search_depth= @tmp_mdev621;
--echo #
--echo # MDEV-7992: Nested left joins + 'not exists' optimization
--echo #
CREATE TABLE t1(
K1 INT PRIMARY KEY,
Name VARCHAR(15)
);
INSERT INTO t1 VALUES
(1,'T1Row1'), (2,'T1Row2');
CREATE TABLE t2(
K2 INT PRIMARY KEY,
K1r INT,
rowTimestamp DATETIME,
Event VARCHAR(15)
);
INSERT INTO t2 VALUES
(1, 1, '2015-04-13 10:42:11' ,'T1Row1Event1'),
(2, 1, '2015-04-13 10:42:12' ,'T1Row1Event2'),
(3, 1, '2015-04-13 10:42:12' ,'T1Row1Event3');
let $q1=
SELECT t1a.*, t2a.*,
t2i.K2 AS K2B, t2i.K1r AS K1rB,
t2i.rowTimestamp AS rowTimestampB, t2i.Event AS EventB
FROM
t1 t1a JOIN t2 t2a ON t2a.K1r = t1a.K1
LEFT JOIN
( t1 t1i LEFT JOIN t2 t2i ON t2i.K1r = t1i.K1)
ON (t1i.K1 = 1) AND
(((t2i.K1r = t1a.K1 AND t2i.rowTimestamp > t2a.rowTimestamp ) OR
(t2i.rowTimestamp = t2a.rowTimestamp AND t2i.K2 > t2a.K2))
OR (t2i.K2 IS NULL))
WHERE
t2a.K1r = 1 AND t2i.K2 IS NULL;
eval $q1;
eval EXPLAIN EXTENDED $q1;
CREATE VIEW v1 AS
SELECT t2i.*
FROM t1 as t1i LEFT JOIN t2 as t2i ON t2i.K1r = t1i.K1
WHERE t1i.K1 = 1 ;
let $q2=
SELECT
t1a.*, t2a.*, t2b.K2 as K2B, t2b.K1r as K1rB,
t2b.rowTimestamp as rowTimestampB, t2b.Event as EventB
FROM
t1 as t1a JOIN t2 as t2a ON t2a.K1r = t1a.K1
LEFT JOIN
v1 as t2b
ON ((t2b.K1r = t1a.K1 AND t2b.rowTimestamp > t2a.rowTimestamp) OR
(t2b.rowTimestamp = t2a.rowTimestamp AND t2b.K2 > t2a.K2))
OR (t2b.K2 IS NULL)
WHERE
t1a.K1 = 1 AND
t2b.K2 IS NULL;
eval $q2;
eval EXPLAIN EXTENDED $q2;
DROP VIEW v1;
DROP TABLE t1,t2;
set optimizer_search_depth= @tmp_mdev621;

67
sql/sql_select.cc
View File

@ -7793,8 +7793,6 @@ get_best_combination(JOIN *join)
form=join->table[tablenr]=j->table;
used_tables|= form->map;
form->reginfo.join_tab=j;
if (!*j->on_expr_ref)
form->reginfo.not_exists_optimize=0; // Only with LEFT JOIN
DBUG_PRINT("info",("type: %d", j->type));
if (j->type == JT_CONST)
goto loop_end; // Handled in make_join_stat..
@ -8626,6 +8624,9 @@ make_outerjoin_info(JOIN *join)
if (embedding && !embedding->is_active_sjm())
tab->first_upper= embedding->nested_join->first_nested;
}
else if (!embedding)
tab->table->reginfo.not_exists_optimize= 0;
for ( ; embedding ; embedding= embedding->embedding)
{
if (embedding->is_active_sjm())
@ -8635,7 +8636,10 @@ make_outerjoin_info(JOIN *join)
}
/* Ignore sj-nests: */
if (!(embedding->on_expr && embedding->outer_join))
{
tab->table->reginfo.not_exists_optimize= 0;
continue;
}
NESTED_JOIN *nested_join= embedding->nested_join;
if (!nested_join->counter)
{
@ -8651,17 +8655,10 @@ make_outerjoin_info(JOIN *join)
}
if (!tab->first_inner)
tab->first_inner= nested_join->first_nested;
if (tab->table->reginfo.not_exists_optimize)
tab->first_inner->table->reginfo.not_exists_optimize= 1;
if (++nested_join->counter < nested_join->n_tables)
break;
/* Table tab is the last inner table for nested join. */
nested_join->first_nested->last_inner= tab;
if (tab->first_inner->table->reginfo.not_exists_optimize)
{
for (JOIN_TAB *join_tab= tab->first_inner; join_tab <= tab; join_tab++)
join_tab->table->reginfo.not_exists_optimize= 1;
}
}
}
DBUG_RETURN(FALSE);
@ -17099,32 +17096,41 @@ evaluate_join_record(JOIN *join, JOIN_TAB *join_tab,
first_unmatched->found= 1;
for (JOIN_TAB *tab= first_unmatched; tab <= join_tab; tab++)
{
/*
Check whether 'not exists' optimization can be used here.
If tab->table->reginfo.not_exists_optimize is set to true
then WHERE contains a conjunctive predicate IS NULL over
a non-nullable field of tab. When activated this predicate
will filter out all records with matches for the left part
of the outer join whose inner tables start from the
first_unmatched table and include table tab. To safely use
'not exists' optimization we have to check that the
IS NULL predicate is really activated, i.e. all guards
that wrap it are in the 'open' state.
*/
bool not_exists_opt_is_applicable=
tab->table->reginfo.not_exists_optimize;
for (JOIN_TAB *first_upper= first_unmatched->first_upper;
not_exists_opt_is_applicable && first_upper;
first_upper= first_upper->first_upper)
{
if (!first_upper->found)
not_exists_opt_is_applicable= false;
}
/* Check all predicates that has just been activated. */
/*
Actually all predicates non-guarded by first_unmatched->found
will be re-evaluated again. It could be fixed, but, probably,
it's not worth doing now.
*/
/*
not_exists_optimize has been created from a
select_cond containing 'is_null'. This 'is_null'
predicate is still present on any 'tab' with
'not_exists_optimize'. Furthermore, the usual rules
for condition guards also applies for
'not_exists_optimize' -> When 'is_null==false' we
know all cond. guards are open and we can apply
the 'not_exists_optimize'.
*/
DBUG_ASSERT(!(tab->table->reginfo.not_exists_optimize &&
!tab->select_cond));
if (tab->select_cond && !tab->select_cond->val_int())
{
/* The condition attached to table tab is false */
if (tab == join_tab)
{
found= 0;
if (not_exists_opt_is_applicable)
DBUG_RETURN(NESTED_LOOP_NO_MORE_ROWS);
}
else
{
@ -17133,20 +17139,9 @@ evaluate_join_record(JOIN *join, JOIN_TAB *join_tab,
not to the last table of the current nest level.
*/
join->return_tab= tab;
}
if (tab->table->reginfo.not_exists_optimize)
{
/*
When not_exists_optimize is set: No need to further
explore more rows of 'tab' for this partial result.
Any found 'tab' matches are known to evaluate to 'false'.
Returning .._NO_MORE_ROWS will skip rem. 'tab' rows.
*/
if (not_exists_opt_is_applicable)
DBUG_RETURN(NESTED_LOOP_NO_MORE_ROWS);
}
else if (tab != join_tab)
{
else
DBUG_RETURN(NESTED_LOOP_OK);
}
}