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MDEV-17493: Partition pruning doesn't work for nested outer joins

Browse source 
Reuse the fix for MDEV-17518 here, too.
This commit is contained in:
Sergei Petrunia 2018-10-23 11:23:34 +02:00
parent 03680a9b4f
commit 3b6d903852
4 changed files with 120 additions and 61 deletions
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33
mysql-test/main/partition_pruning.result
View file

@ -3484,3 +3484,36 @@ select * from t1 where (a = 1 AND b < 'd' AND (c = 'b' OR (c = 'c' AND d = 1)) O
a b c d
1 a b 1
drop table t1;
#
# MDEV-17493: Partition pruning doesn't work for nested outer joins
#
create table t0(a int);
insert into t0 values (0),(1),(2),(3),(4),(5),(6),(7),(8),(9);
create table t1 (a int, b int, c int);
insert into t1 select a,a,a from t0;
create table t2 (a int, b int, c int);
insert into t2 select a,a,a from t0;
create table t3 (
part_id int,
a int
) partition by list (part_id) (
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 t3 select mod(a,5), a from t0;
explain partitions
select * from t1 left join t3 on (t1.a=t3.a and t3.part_id=3);
id select_type table partitions type possible_keys key key_len ref rows Extra
1 SIMPLE t1 NULL ALL NULL NULL NULL NULL 10
1 SIMPLE t3 p3 ALL NULL NULL NULL NULL 2 Using where; Using join buffer (flat, BNL join)
# The following should have partitions="p3", NOT p0,p1,p2,p3,p4:
explain partitions
select * from t1 left join (t3 join t2) on (t1.a=t3.a and t3.a=t2.b and t3.part_id=3);
id select_type table partitions type possible_keys key key_len ref rows Extra
1 SIMPLE t1 NULL ALL NULL NULL NULL NULL 10
1 SIMPLE t3 p3 ALL NULL NULL NULL NULL 2 Using where; Using join buffer (flat, BNL join)
1 SIMPLE t2 NULL ALL NULL NULL NULL NULL 10 Using where; Using join buffer (incremental, BNL join)
drop table t0,t1,t2,t3;

31
mysql-test/main/partition_pruning.test
View file

@ -1535,4 +1535,35 @@ select * from t1 where (a = 1 AND b < 'd' AND (c = 'b' OR (c = 'c' AND d = 1)) O
(a = 1 AND b >= 'a' AND (c = 'c' OR (c = 'd' AND d = 2))));
drop table t1;
--echo #
--echo # MDEV-17493: Partition pruning doesn't work for nested outer joins
--echo #
create table t0(a int);
insert into t0 values (0),(1),(2),(3),(4),(5),(6),(7),(8),(9);
create table t1 (a int, b int, c int);
insert into t1 select a,a,a from t0;
create table t2 (a int, b int, c int);
insert into t2 select a,a,a from t0;
create table t3 (
part_id int,
a int
) partition by list (part_id) (
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 t3 select mod(a,5), a from t0;
explain partitions
select * from t1 left join t3 on (t1.a=t3.a and t3.part_id=3);
--echo # The following should have partitions="p3", NOT p0,p1,p2,p3,p4:
explain partitions
select * from t1 left join (t3 join t2) on (t1.a=t3.a and t3.a=t2.b and t3.part_id=3);
drop table t0,t1,t2,t3;

109
sql/sql_select.cc
View file

@ -292,6 +292,9 @@ static bool find_order_in_list(THD *, Ref_ptr_array, TABLE_LIST *, ORDER *,
static double table_cond_selectivity(JOIN *join, uint idx, JOIN_TAB *s,
table_map rem_tables);
void set_postjoin_aggr_write_func(JOIN_TAB *tab);
static Item **get_sargable_cond(JOIN *join, TABLE *table);
#ifndef DBUG_OFF
/*
@ -1770,19 +1773,9 @@ JOIN::optimize_inner()
List_iterator_fast<TABLE_LIST> li(select_lex->leaf_tables);
while ((tbl= li++))
{
/*
If tbl->embedding!=NULL that means that this table is in the inner
part of the nested outer join, and we can't do partition pruning
(TODO: check if this limitation can be lifted)
*/
if (!tbl->embedding ||
(tbl->embedding && tbl->embedding->sj_on_expr))
{
Item *prune_cond= tbl->on_expr? tbl->on_expr : conds;
tbl->table->all_partitions_pruned_away= prune_partitions(thd,
tbl->table,
prune_cond);
}
Item **prune_cond= get_sargable_cond(this, tbl->table);
tbl->table->all_partitions_pruned_away=
prune_partitions(thd, tbl->table, *prune_cond);
}
}
#endif
@ -4334,6 +4327,47 @@ void mark_join_nest_as_const(JOIN *join,
}
}
/*
@brief Get the condition that can be used to do range analysis/partition
pruning/etc
@detail
Figure out which condition we can use:
- For INNER JOIN, we use the WHERE,
- "t1 LEFT JOIN t2 ON ..." uses t2's ON expression
- "t1 LEFT JOIN (...) ON ..." uses the join nest's ON expression.
*/
static Item **get_sargable_cond(JOIN *join, TABLE *table)
{
Item **retval;
if (table->pos_in_table_list->on_expr)
{
/*
This is an inner table from a single-table LEFT JOIN, "t1 LEFT JOIN
t2 ON cond". Use the condition cond.
*/
retval= &table->pos_in_table_list->on_expr;
}
else if (table->pos_in_table_list->embedding &&
!table->pos_in_table_list->embedding->sj_on_expr)
{
/*
This is the inner side of a multi-table outer join. Use the
appropriate ON expression.
*/
retval= &(table->pos_in_table_list->embedding->on_expr);
}
else
{
/* The table is not inner wrt some LEFT JOIN. Use the WHERE clause */
retval= &join->conds;
}
return retval;
}
/**
Calculate the best possible join and initialize the join structure.
@ -4919,42 +4953,11 @@ make_join_statistics(JOIN *join, List<TABLE_LIST> &tables_list,
SQL_SELECT *select= 0;
if (!s->const_keys.is_clear_all())
{
Item *sargable_cond;
int cond_source;
/*
Figure out which condition we should use for range analysis. For
INNER JOIN, we use the WHERE, for inner side of LEFT JOIN we should
use the ON expression.
*/
if (*s->on_expr_ref)
{
/*
This is an inner table from a single-table LEFT JOIN, "t1 LEFT JOIN
t2 ON cond". Use the condition cond.
*/
cond_source= 0;
sargable_cond= *s->on_expr_ref;
}
else if (s->table->pos_in_table_list->embedding &&
!s->table->pos_in_table_list->embedding->sj_on_expr)
{
/*
This is the inner side of a multi-table outer join. Use the
appropriate ON expression.
*/
cond_source= 1;
sargable_cond= s->table->pos_in_table_list->embedding->on_expr;
}
else
{
/* The table is not inner wrt some LEFT JOIN. Use the WHERE clause */
cond_source= 2;
sargable_cond= join->conds;
}
Item **sargable_cond= get_sargable_cond(join, s->table);
select= make_select(s->table, found_const_table_map,
found_const_table_map,
sargable_cond,
*sargable_cond,
(SORT_INFO*) 0,
1, &error);
if (!select)
@ -4966,19 +4969,7 @@ make_join_statistics(JOIN *join, List<TABLE_LIST> &tables_list,
Range analyzer might have modified the condition. Put it the new
condition to where we got it from.
*/
switch (cond_source) {
case 0:
*s->on_expr_ref= select->cond;
break;
case 1:
s->table->pos_in_table_list->embedding->on_expr= select->cond;
break;
case 2:
join->conds= select->cond;
break;
default:
DBUG_ASSERT(0);
}
*sargable_cond= select->cond;
s->quick=select->quick;
s->needed_reg=select->needed_reg;

8
sql/sql_select.h
View file

@ -263,8 +263,12 @@ typedef struct st_join_table {
/*
Pointer to the associated ON expression. on_expr_ref=!NULL except for
degenerate joins.
*on_expr_ref!=NULL for tables that are first inner tables within an outer
join.
Optimization phase: *on_expr_ref!=NULL for tables that are the single
tables on the inner side of the outer join (t1 LEFT JOIN t2 ON...)
Execution phase: *on_expr_ref!=NULL for tables that are first inner tables
within an outer join (which may have multiple tables)
*/
Item **on_expr_ref;
COND_EQUAL *cond_equal; /**< multiple equalities for the on expression */