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Fixes done while working on MDEV-4119:

Browse Source 
Fixed several optimizer issues relatied to GROUP BY:

a) Refering to a SELECT column in HAVING sometimes calculated it twice, which caused problems with non determinstic functions

b) Removing duplicate fields and constants from GROUP BY was done too late for "using index for group by" optimization to work

c) EXPLAIN SELECT ... GROUP BY did wrongly show 'Using filesort' in some cases involving "Using index for group-by"


a) was fixed by:
- Changed last argument to Item::split_sum_func2() from bool to int to allow more flags
- Added flag argument to Item::split_sum_func() to allow on to specify if the item was in the SELECT part
- Mark all split_sum_func() calls from SELECT with SPLIT_SUM_SELECT
- Changed split_sum_func2() to do nothing if called with an argument that is not a sum function and doesn't include sum functions, if we are not an argument to SELECT.

This ensures that in a case like
select a*sum(b) as f1 from t1 where a=1 group by c having f1 <= 10;

That 'a' in the SELECT part is stored as a reference in the temporary table togeher with sum(b) while the 'a' in having isn't (not needed as 'a' is already a reference to a column in the result)

b) was fixed by:
- Added an extra remove_const() pass for GROUP BY arguments before make_join_statistics() in case of one table SELECT.

This allowes get_best_group_min_max() to optimize things better.

c) was fixed by:
- Added test for group by optimization in JOIN::exec_inner for
  select->quick->get_type() == QUICK_SELECT_I::QS_TYPE_GROUP_MIN_MAX

item.cc:
- Simplifed Item::split_sum_func2()
  - Split test to make them faster and easier to read
  - Changed last argument to Item::split_sum_func2() from bool to int to allow more flags
  - Added flag argument to Item::split_sum_func() to allow on to specify if the item was in the SELECT part
  - Changed split_sum_func2() to do nothing if called with an argument that is not a sum function and doesn't include sum functions, if we are not an argument to SELECT.

opt_range.cc:
- Simplified get_best_group_min_max() by calcuating first how many group_by elements.
- Use join->group instead of join->group_list to test if group by, as join->group_list may be NULL if everything was optimized away.

sql_select.cc:
- Added an extra remove_const() pass for GROUP BY arguments before make_join_statistics() in case of one table SELECT.
- Use group instead of group_list to test if group by, as group_list may be NULL if everything was optimized away.
- Moved printing of "Error in remove_const" to remove_const() instead of having it in caller.
- Simplified some if tests by re-ordering code.
- update_depend_map_for_order() and remove_const() fixed to handle the case where make_join_statistics() has not yet been called (join->join_tab is 0 in this case)
This commit is contained in:
Monty 2015-07-05 12:39:46 +03:00
parent 79af0b3823
commit 86377d078e
14 changed files with 329 additions and 136 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

88
mysql-test/r/group_by.result
View File

@ -522,6 +522,7 @@ NULL 9
3
b 1
drop table t1;
set big_tables=0;
create table t1 (a int not null, b int not null);
insert into t1 values (1,1),(1,2),(3,1),(3,2),(2,2),(2,1);
create table t2 (a int not null, b int not null, key(a));
@ -659,7 +660,10 @@ insert into t1 (a,b) values (1,2),(1,3),(2,5);
select a, 0.1*0+1 r2, sum(1) r1 from t1 where a = 1 group by a having r1>1 and r2=1;
a r2 r1
1 1.0 2
select a, round(rand(100)*10) r2, sum(1) r1 from t1 where a = 1 group by a having r1>1 and r2<=2;
select a, round(rand(100)*10) r2, sum(1) r1 from t1 where a = 1 group by a having r1>1 and r2<=2;
a r2 r1
1 2 2
select a, round(rand(100)*10) r2, sum(1) r1 from t1 group by a having r1>1 and r2<=2;
a r2 r1
1 2 2
select a,sum(b) from t1 where a=1 group by c;
@ -668,6 +672,12 @@ a sum(b)
select a*sum(b) from t1 where a=1 group by c;
a*sum(b)
5
select a*sum(b) as f1 from t1 where a=1 group by c having f1 <= 10;
f1
5
select a,a*sum(b) as f1 from t1 where a=1 group by c having a*sum(b)+0 <= 10;
a f1
1 5
select sum(a)*sum(b) from t1 where a=1 group by c;
sum(a)*sum(b)
10
@ -1988,12 +1998,12 @@ SHOW SESSION STATUS LIKE 'Sort_scan%';
Variable_name Value
Sort_scan 0
EXPLAIN SELECT SQL_BIG_RESULT col1 AS field1, col1 AS field2
FROM t1 GROUP BY field1, field2;;
FROM t1 GROUP BY field1, field2;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 index NULL idx 5 NULL 20 Using index; Using filesort
FLUSH STATUS;
SELECT SQL_BIG_RESULT col1 AS field1, col1 AS field2
FROM t1 GROUP BY field1, field2;;
FROM t1 GROUP BY field1, field2;
field1 field2
1 1
2 2
@ -2082,6 +2092,58 @@ f1 f2
19 19
20 20
explain
select col1 f1, col1 f2 from t1 group by f1;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 index NULL idx 5 NULL 20 Using index
select col1 f1, col1 f2 from t1 group by f1;
f1 f2
1 1
2 2
3 3
4 4
5 5
6 6
7 7
8 8
9 9
10 10
11 11
12 12
13 13
14 14
15 15
16 16
17 17
18 18
19 19
20 20
explain
select col1 f1, col1 f2 from t1 group by f1, f2;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 index NULL idx 5 NULL 20 Using index
select col1 f1, col1 f2 from t1 group by f1, f2;
f1 f2
1 1
2 2
3 3
4 4
5 5
6 6
7 7
8 8
9 9
10 10
11 11
12 12
13 13
14 14
15 15
16 16
17 17
18 18
19 19
20 20
explain
select col1 f1, col1 f2 from t1 group by f2 order by f2, f1;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 index NULL idx 5 NULL 20 Using index
@ -2141,6 +2203,22 @@ INSERT INTO t2(col1, col2) VALUES
(1,20),(2,19),(3,18),(4,17),(5,16),(6,15),(7,14),(8,13),(9,12),(10,11),
(11,10),(12,9),(13,8),(14,7),(15,6),(16,5),(17,4),(18,3),(19,2),(20,1);
explain
select col1 f1, col2 f2, col1 f3 from t2 group by f1;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t2 range NULL idx 5 NULL 7 Using index for group-by
explain
select SQL_BIG_RESULT col1 f1, col2 f2, col1 f3 from t2 group by f1;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t2 range NULL idx 5 NULL 7 Using index for group-by
explain
select col1 f1, col2 f2, col1 f3 from t2 group by f1, f2;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t2 index NULL idx 10 NULL 20 Using index
explain
select col1 f1, col1 f2 from t2 group by f1, 1+1;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t2 range NULL idx 5 NULL 7 Using index for group-by
explain
select col1 f1, col2 f2, col1 f3 from t2 group by f1, f2, f3+0;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t2 index NULL idx 10 NULL 20 Using index; Using temporary; Using filesort
@ -2167,6 +2245,10 @@ f1 f2 f3
19 2 19
20 1 20
explain
select col1 f1, col2 f2, col1 f3 from t2 order by f1,f2;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t2 index NULL idx 10 NULL 20 Using index
explain
select col1 f1, col2 f2, col1 f3 from t2 order by f1, f2, f3+0;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t2 index NULL idx 10 NULL 20 Using index; Using filesort

30
mysql-test/t/group_by.test
View File

@ -394,6 +394,7 @@ select a,count(*) from t1 group by a;
set big_tables=1;
select a,count(*) from t1 group by a;
drop table t1;
set big_tables=0;
#
# Test of GROUP BY ... ORDER BY NULL optimization
@ -485,9 +486,12 @@ create table t1 (a integer, b integer, c integer);
insert into t1 (a,b) values (1,2),(1,3),(2,5);
select a, 0.1*0+1 r2, sum(1) r1 from t1 where a = 1 group by a having r1>1 and r2=1;
# rand(100)*10 will be < 2 only for the first row (of 6)
select a, round(rand(100)*10) r2, sum(1) r1 from t1 where a = 1 group by a having r1>1 and r2<=2;
select a, round(rand(100)*10) r2, sum(1) r1 from t1 where a = 1 group by a having r1>1 and r2<=2;
select a, round(rand(100)*10) r2, sum(1) r1 from t1 group by a having r1>1 and r2<=2;
select a,sum(b) from t1 where a=1 group by c;
select a*sum(b) from t1 where a=1 group by c;
select a*sum(b) as f1 from t1 where a=1 group by c having f1 <= 10;
select a,a*sum(b) as f1 from t1 where a=1 group by c having a*sum(b)+0 <= 10;
select sum(a)*sum(b) from t1 where a=1 group by c;
select a,sum(b) from t1 where a=1 group by c having a=1;
select a as d,sum(b) from t1 where a=1 group by c having d=1;
@ -1346,9 +1350,9 @@ let $query=SELECT SQL_BIG_RESULT col1 AS field1, col1 AS field2
FROM t1 GROUP BY field1, field2;
# Needs to be range to exercise bug
--eval EXPLAIN $query;
--eval EXPLAIN $query
FLUSH STATUS;
--eval $query;
--eval $query
SHOW SESSION STATUS LIKE 'Sort_scan%';
CREATE VIEW v1 AS SELECT * FROM t1;
@ -1368,6 +1372,14 @@ explain
select col1 f1, col1 f2 from t1 order by f2, f1+0;
select col1 f1, col1 f2 from t1 order by f2, f1+0;
explain
select col1 f1, col1 f2 from t1 group by f1;
select col1 f1, col1 f2 from t1 group by f1;
explain
select col1 f1, col1 f2 from t1 group by f1, f2;
select col1 f1, col1 f2 from t1 group by f1, f2;
explain
select col1 f1, col1 f2 from t1 group by f2 order by f2, f1;
select col1 f1, col1 f2 from t1 group by f2 order by f2, f1;
@ -1376,6 +1388,7 @@ explain
select col1 f1, col1 f2 from t1 group by f1, f2 order by f2, f1;
select col1 f1, col1 f2 from t1 group by f1, f2 order by f2, f1;
CREATE TABLE t2(
col1 int,
col2 int,
@ -1385,10 +1398,21 @@ INSERT INTO t2(col1, col2) VALUES
(1,20),(2,19),(3,18),(4,17),(5,16),(6,15),(7,14),(8,13),(9,12),(10,11),
(11,10),(12,9),(13,8),(14,7),(15,6),(16,5),(17,4),(18,3),(19,2),(20,1);
explain
select col1 f1, col2 f2, col1 f3 from t2 group by f1;
explain
select SQL_BIG_RESULT col1 f1, col2 f2, col1 f3 from t2 group by f1;
explain
select col1 f1, col2 f2, col1 f3 from t2 group by f1, f2;
explain
select col1 f1, col1 f2 from t2 group by f1, 1+1;
explain
select col1 f1, col2 f2, col1 f3 from t2 group by f1, f2, f3+0;
select col1 f1, col2 f2, col1 f3 from t2 group by f1, f2, f3+0;
explain
select col1 f1, col2 f2, col1 f3 from t2 order by f1,f2;
explain
select col1 f1, col2 f2, col1 f3 from t2 order by f1, f2, f3+0;
select col1 f1, col2 f2, col1 f3 from t2 order by f1, f2, f3+0;

121
sql/item.cc
View File

@ -1705,69 +1705,98 @@ public:
@param thd Thread handler
@param ref_pointer_array Pointer to array of reference fields
@param fields All fields in select
@param fields All fields in select
@param ref Pointer to item
@param skip_registered <=> function be must skipped for registered
SUM items
@param split_flags Zero or more of the following flags
SPLIT_FUNC_SKIP_REGISTERED:
Function be must skipped for registered SUM
SUM items
SPLIT_FUNC_SELECT
We are called on the select level and have to
register items operated on sum function
@note
This is from split_sum_func2() for items that should be split
All found SUM items are added FIRST in the fields list and
we replace the item with a reference.
If this is an item in the SELECT list then we also have to split out
all arguments to functions used together with the sum function.
For example in case of SELECT A*sum(B) we have to split out both
A and sum(B).
This is not needed for ORDER BY, GROUP BY or HAVING as all references
to items in the select list are already of type REF
thd->fatal_error() may be called if we are out of memory
*/
void Item::split_sum_func2(THD *thd, Item **ref_pointer_array,
List<Item> &fields, Item **ref,
bool skip_registered)
uint split_flags)
{
/* An item of type Item_sum is registered <=> ref_by != 0 */
if (type() == SUM_FUNC_ITEM && skip_registered &&
((Item_sum *) this)->ref_by)
return;
if ((type() != SUM_FUNC_ITEM && with_sum_func) ||
(type() == FUNC_ITEM &&
(((Item_func *) this)->functype() == Item_func::ISNOTNULLTEST_FUNC ||
((Item_func *) this)->functype() == Item_func::TRIG_COND_FUNC)))
if (unlikely(type() == SUM_FUNC_ITEM))
{
/* Will split complicated items and ignore simple ones */
split_sum_func(thd, ref_pointer_array, fields);
/* An item of type Item_sum is registered if ref_by != 0 */
if ((split_flags & SPLIT_SUM_SKIP_REGISTERED) &&
((Item_sum *) this)->ref_by)
return;
}
else if ((type() == SUM_FUNC_ITEM || (used_tables() & ~PARAM_TABLE_BIT)) &&
type() != SUBSELECT_ITEM &&
(type() != REF_ITEM ||
((Item_ref*)this)->ref_type() == Item_ref::VIEW_REF))
else
{
/*
Replace item with a reference so that we can easily calculate
it (in case of sum functions) or copy it (in case of fields)
/* Not a SUM() function */
if (unlikely((!with_sum_func && !(split_flags & SPLIT_SUM_SELECT))))
{
/*
This is not a SUM function and there are no SUM functions inside.
Nothing more to do.
*/
return;
}
if (likely(with_sum_func ||
(type() == FUNC_ITEM &&
(((Item_func *) this)->functype() ==
Item_func::ISNOTNULLTEST_FUNC ||
((Item_func *) this)->functype() ==
Item_func::TRIG_COND_FUNC))))
{
/* Will call split_sum_func2() for all items */
split_sum_func(thd, ref_pointer_array, fields, split_flags);
return;
}
The test above is to ensure we don't do a reference for things
that are constants (PARAM_TABLE_BIT is in effect a constant)
or already referenced (for example an item in HAVING)
Exception is Item_direct_view_ref which we need to convert to
Item_ref to allow fields from view being stored in tmp table.
*/
Item_aggregate_ref *item_ref;
uint el= fields.elements;
/*
If this is an item_ref, get the original item
This is a safety measure if this is called for things that is
already a reference.
*/
Item *real_itm= real_item();
ref_pointer_array[el]= real_itm;
if (!(item_ref= new Item_aggregate_ref(&thd->lex->current_select->context,
ref_pointer_array + el, 0, name)))
return; // fatal_error is set
if (type() == SUM_FUNC_ITEM)
item_ref->depended_from= ((Item_sum *) this)->depended_from();
fields.push_front(real_itm);
thd->change_item_tree(ref, item_ref);
if (unlikely((!(used_tables() & ~PARAM_TABLE_BIT) ||
type() == SUBSELECT_ITEM ||
(type() == REF_ITEM &&
((Item_ref*)this)->ref_type() != Item_ref::VIEW_REF))))
return;
}
/*
Replace item with a reference so that we can easily calculate
it (in case of sum functions) or copy it (in case of fields)
The test above is to ensure we don't do a reference for things
that are constants (PARAM_TABLE_BIT is in effect a constant)
or already referenced (for example an item in HAVING)
Exception is Item_direct_view_ref which we need to convert to
Item_ref to allow fields from view being stored in tmp table.
*/
Item_aggregate_ref *item_ref;
uint el= fields.elements;
/*
If this is an item_ref, get the original item
This is a safety measure if this is called for things that is
already a reference.
*/
Item *real_itm= real_item();
ref_pointer_array[el]= real_itm;
if (!(item_ref= new Item_aggregate_ref(&thd->lex->current_select->context,
ref_pointer_array + el, 0, name)))
return; // fatal_error is set
if (type() == SUM_FUNC_ITEM)
item_ref->depended_from= ((Item_sum *) this)->depended_from();
fields.push_front(real_itm);
thd->change_item_tree(ref, item_ref);
}

8
sql/item.h
View File

@ -74,6 +74,10 @@ char_to_byte_length_safe(uint32 char_length_arg, uint32 mbmaxlen_arg)
}
/* Bits for the split_sum_func() function */
#define SPLIT_SUM_SKIP_REGISTERED 1 /* Skip registered funcs */
#define SPLIT_SUM_SELECT 2 /* SELECT item; Split all parts */
/*
"Declared Type Collation"
A combination of collation and its derivation.
@ -1169,10 +1173,10 @@ public:
return false;
}
virtual void split_sum_func(THD *thd, Item **ref_pointer_array,
List<Item> &fields) {}
List<Item> &fields, uint flags) {}
/* Called for items that really have to be split */
void split_sum_func2(THD *thd, Item **ref_pointer_array, List<Item> &fields,
Item **ref, bool skip_registered);
Item **ref, uint flags);
virtual bool get_date(MYSQL_TIME *ltime, ulonglong fuzzydate);
bool get_time(MYSQL_TIME *ltime)
{ return get_date(ltime, TIME_TIME_ONLY | TIME_INVALID_DATES); }

5
sql/item_cmpfunc.cc
View File

@ -4575,12 +4575,13 @@ void Item_cond::traverse_cond(Cond_traverser traverser,
*/
void Item_cond::split_sum_func(THD *thd, Item **ref_pointer_array,
List<Item> &fields)
List<Item> &fields, uint flags)
{
List_iterator<Item> li(list);
Item *item;
while ((item= li++))
item->split_sum_func2(thd, ref_pointer_array, fields, li.ref(), TRUE);
item->split_sum_func2(thd, ref_pointer_array, fields, li.ref(),
flags | SPLIT_SUM_SKIP_REGISTERED);
}

3
sql/item_cmpfunc.h
View File

@ -1759,7 +1759,8 @@ public:
SARGABLE_PARAM **sargables);
SEL_TREE *get_mm_tree(RANGE_OPT_PARAM *param, Item **cond_ptr);
virtual void print(String *str, enum_query_type query_type);
void split_sum_func(THD *thd, Item **ref_pointer_array, List<Item> &fields);
void split_sum_func(THD *thd, Item **ref_pointer_array, List<Item> &fields,
uint flags);
friend int setup_conds(THD *thd, TABLE_LIST *tables, TABLE_LIST *leaves,
COND **conds);
void top_level_item() { abort_on_null=1; }

5
sql/item_func.cc
View File

@ -419,11 +419,12 @@ Item *Item_func::compile(Item_analyzer analyzer, uchar **arg_p,
*/
void Item_func::split_sum_func(THD *thd, Item **ref_pointer_array,
List<Item> &fields)
List<Item> &fields, uint flags)
{
Item **arg, **arg_end;
for (arg= args, arg_end= args+arg_count; arg != arg_end ; arg++)
(*arg)->split_sum_func2(thd, ref_pointer_array, fields, arg, TRUE);
(*arg)->split_sum_func2(thd, ref_pointer_array, fields, arg,
flags | SPLIT_SUM_SKIP_REGISTERED);
}

3
sql/item_func.h
View File

@ -143,7 +143,8 @@ public:
sync_with_sum_func_and_with_field(list);
list.empty(); // Fields are used
}
void split_sum_func(THD *thd, Item **ref_pointer_array, List<Item> &fields);
void split_sum_func(THD *thd, Item **ref_pointer_array, List<Item> &fields,
uint flags);
virtual void print(String *str, enum_query_type query_type);
void print_op(String *str, enum_query_type query_type);
void print_args(String *str, uint from, enum_query_type query_type);

5
sql/item_row.cc
View File

@ -101,11 +101,12 @@ void Item_row::cleanup()
void Item_row::split_sum_func(THD *thd, Item **ref_pointer_array,
List<Item> &fields)
List<Item> &fields, uint flags)
{
Item **arg, **arg_end;
for (arg= args, arg_end= args + arg_count; arg != arg_end ; arg++)
(*arg)->split_sum_func2(thd, ref_pointer_array, fields, arg, TRUE);
(*arg)->split_sum_func2(thd, ref_pointer_array, fields, arg,
flags | SPLIT_SUM_SKIP_REGISTERED);
}

3
sql/item_row.h
View File

@ -75,7 +75,8 @@ public:
bool fix_fields(THD *thd, Item **ref);
void fix_after_pullout(st_select_lex *new_parent, Item **ref);
void cleanup();
void split_sum_func(THD *thd, Item **ref_pointer_array, List<Item> &fields);
void split_sum_func(THD *thd, Item **ref_pointer_array, List<Item> &fields,
uint flags);
table_map used_tables() const { return used_tables_cache; };
bool const_item() const { return const_item_cache; };
enum Item_result result_type() const { return ROW_RESULT; }

26
sql/opt_range.cc
View File

@ -12811,6 +12811,7 @@ get_best_group_min_max(PARAM *param, SEL_TREE *tree, double read_time)
uint key_infix_len= 0; /* Length of key_infix. */
TRP_GROUP_MIN_MAX *read_plan= NULL; /* The eventually constructed TRP. */
uint key_part_nr;
uint elements_in_group;
ORDER *tmp_group;
Item *item;
Item_field *item_field;
@ -12892,10 +12893,12 @@ get_best_group_min_max(PARAM *param, SEL_TREE *tree, double read_time)
}
/* Check (GA4) - that there are no expressions among the group attributes. */
elements_in_group= 0;
for (tmp_group= join->group_list; tmp_group; tmp_group= tmp_group->next)
{
if ((*tmp_group->item)->real_item()->type() != Item::FIELD_ITEM)
DBUG_RETURN(NULL);
elements_in_group++;
}
/*
@ -12944,8 +12947,16 @@ get_best_group_min_max(PARAM *param, SEL_TREE *tree, double read_time)
there are cases Loose Scan over a multi-part index is useful).
*/
if (!table->covering_keys.is_set(cur_index))
goto next_index;
continue;
/*
This function is called on the precondition that the index is covering.
Therefore if the GROUP BY list contains more elements than the index,
these are duplicates. The GROUP BY list cannot be a prefix of the index.
*/
if (elements_in_group > table->actual_n_key_parts(cur_index_info))
continue;
/*
Unless extended keys can be used for cur_index:
If the current storage manager is such that it appends the primary key to
@ -13006,13 +13017,6 @@ get_best_group_min_max(PARAM *param, SEL_TREE *tree, double read_time)
else
goto next_index;
}
/*
This function is called on the precondition that the index is covering.
Therefore if the GROUP BY list contains more elements than the index,
these are duplicates. The GROUP BY list cannot be a prefix of the index.
*/
if (cur_part == end_part && tmp_group)
goto next_index;
}
/*
Check (GA2) if this is a DISTINCT query.
@ -13022,8 +13026,8 @@ get_best_group_min_max(PARAM *param, SEL_TREE *tree, double read_time)
Later group_fields_array of ORDER objects is used to convert the query
to a GROUP query.
*/
if ((!join->group_list && join->select_distinct) ||
is_agg_distinct)
if ((!join->group && join->select_distinct) ||
is_agg_distinct)
{
if (!is_agg_distinct)
{

3
sql/sql_base.cc
View File

@ -7935,7 +7935,8 @@ bool setup_fields(THD *thd, Item **ref_pointer_array,
*(ref++)= item;
if (item->with_sum_func && item->type() != Item::SUM_FUNC_ITEM &&
sum_func_list)
item->split_sum_func(thd, ref_pointer_array, *sum_func_list);
item->split_sum_func(thd, ref_pointer_array, *sum_func_list,
SPLIT_SUM_SELECT);
thd->lex->used_tables|= item->used_tables();
thd->lex->current_select->cur_pos_in_select_list++;
}

164
sql/sql_select.cc
View File

@ -854,7 +854,7 @@ JOIN::prepare(Item ***rref_pointer_array,
real_order= TRUE;
if (item->with_sum_func && item->type() != Item::SUM_FUNC_ITEM)
item->split_sum_func(thd, ref_pointer_array, all_fields);
item->split_sum_func(thd, ref_pointer_array, all_fields, 0);
}
if (!real_order)
order= NULL;
@ -862,7 +862,7 @@ JOIN::prepare(Item ***rref_pointer_array,
if (having && having->with_sum_func)
having->split_sum_func2(thd, ref_pointer_array, all_fields,
&having, TRUE);
&having, SPLIT_SUM_SKIP_REGISTERED);
if (select_lex->inner_sum_func_list)
{
Item_sum *end=select_lex->inner_sum_func_list;
@ -871,7 +871,7 @@ JOIN::prepare(Item ***rref_pointer_array,
{
item_sum= item_sum->next;
item_sum->split_sum_func2(thd, ref_pointer_array,
all_fields, item_sum->ref_by, FALSE);
all_fields, item_sum->ref_by, 0);
} while (item_sum != end);
}
@ -1334,6 +1334,24 @@ TODO: make view to decide if it is possible to write to WHERE directly or make S
/* get_sort_by_table() call used to be here: */
MEM_UNDEFINED(&sort_by_table, sizeof(sort_by_table));
/*
We have to remove constants and duplicates from group_list before
calling make_join_statistics() as this may call get_best_group_min_max()
which needs a simplfied group_list.
*/
simple_group= 1;
if (group_list && table_count == 1)
{
group_list= remove_const(this, group_list, conds,
rollup.state == ROLLUP::STATE_NONE,
&simple_group);
if (thd->is_error())
{
error= 1;
DBUG_RETURN(1);
}
}
/* Calculate how to do the join */
THD_STAGE_INFO(thd, stage_statistics);
if (make_join_statistics(this, select_lex->leaf_tables, &keyuse) ||
@ -1549,7 +1567,6 @@ TODO: make view to decide if it is possible to write to WHERE directly or make S
if (thd->is_error())
{
error= 1;
DBUG_PRINT("error",("Error from remove_const"));
DBUG_RETURN(1);
}
@ -1572,14 +1589,14 @@ TODO: make view to decide if it is possible to write to WHERE directly or make S
The FROM clause must contain a single non-constant table.
*/
if (table_count - const_tables == 1 && (group_list || select_distinct) &&
if (table_count - const_tables == 1 && (group || select_distinct) &&
!tmp_table_param.sum_func_count &&
(!join_tab[const_tables].select ||
!join_tab[const_tables].select->quick ||
join_tab[const_tables].select->quick->get_type() !=
QUICK_SELECT_I::QS_TYPE_GROUP_MIN_MAX))
{
if (group_list && rollup.state == ROLLUP::STATE_NONE &&
if (group && rollup.state == ROLLUP::STATE_NONE &&
list_contains_unique_index(join_tab[const_tables].table,
find_field_in_order_list,
(void *) group_list))
@ -1625,7 +1642,7 @@ TODO: make view to decide if it is possible to write to WHERE directly or make S
select_distinct= 0;
}
}
if (group_list || tmp_table_param.sum_func_count)
if (group || tmp_table_param.sum_func_count)
{
if (! hidden_group_fields && rollup.state == ROLLUP::STATE_NONE)
select_distinct=0;
@ -1690,32 +1707,29 @@ TODO: make view to decide if it is possible to write to WHERE directly or make S
else if (thd->is_fatal_error) // End of memory
DBUG_RETURN(1);
}
simple_group= 0;
if (group)
{
ORDER *old_group_list;
group_list= remove_const(this, (old_group_list= group_list), conds,
/*
Update simple_group and group_list as we now have more information, like
which tables or columns are constant.
*/
group_list= remove_const(this, group_list, conds,
rollup.state == ROLLUP::STATE_NONE,
&simple_group);
&simple_group);
if (thd->is_error())
{
error= 1;
DBUG_PRINT("error",("Error from remove_const"));
DBUG_RETURN(1);
}
if (old_group_list && !group_list)
if (!group_list)
{
DBUG_ASSERT(group);
/* The output has only one row */
order=0;
simple_order=1;
select_distinct= 0;
group_optimized_away= 1;
}
}
if (!group_list && group)
{
order=0; // The output has only one row
simple_order=1;
select_distinct= 0; // No need in distinct for 1 row
group_optimized_away= 1;
}
calc_group_buffer(this, group_list);
send_group_parts= tmp_table_param.group_parts; /* Save org parts */
if (procedure && procedure->group)
@ -1725,7 +1739,6 @@ TODO: make view to decide if it is possible to write to WHERE directly or make S
if (thd->is_error())
{
error= 1;
DBUG_PRINT("error",("Error from remove_const"));
DBUG_RETURN(1);
}
calc_group_buffer(this, group_list);
@ -1876,14 +1889,6 @@ TODO: make view to decide if it is possible to write to WHERE directly or make S
if ((select_lex->options & OPTION_SCHEMA_TABLE))
optimize_schema_tables_reads(this);
tmp_having= having;
if (select_options & SELECT_DESCRIBE)
{
error= 0;
goto derived_exit;
}
having= 0;
/*
The loose index scan access method guarantees that all grouping or
duplicate row elimination (for distinct) is already performed
@ -1907,6 +1912,11 @@ TODO: make view to decide if it is possible to write to WHERE directly or make S
error= 0;
tmp_having= having;
if (select_options & SELECT_DESCRIBE)
goto derived_exit;
having= 0;
DBUG_RETURN(0);
setup_subq_exit:
@ -1944,8 +1954,9 @@ int JOIN::init_execution()
/*
Enable LIMIT ROWS EXAMINED during query execution if:
(1) This JOIN is the outermost query (not a subquery or derived table)
This ensures that the limit is enabled when actual execution begins, and
not if a subquery is evaluated during optimization of the outer query.
This ensures that the limit is enabled when actual execution begins,
and not if a subquery is evaluated during optimization of the outer
query.
(2) This JOIN is not the result of a UNION. In this case do not apply the
limit in order to produce the partial query result stored in the
UNION temp table.
@ -2561,19 +2572,26 @@ void JOIN::exec_inner()
simple_order= simple_group;
skip_sort_order= 0;
}
bool made_call= false;
if (order &&
(order != group_list || !(select_options & SELECT_BIG_RESULT)) &&
(const_tables == table_count ||
((simple_order || skip_sort_order) &&
(made_call=true) &&
test_if_skip_sort_order(&join_tab[const_tables], order,
select_limit, 0,
&join_tab[const_tables].table->
if (order && join_tab)
{
bool made_call= false;
SQL_SELECT *select= join_tab[const_tables].select;
if ((order != group_list ||
!(select_options & SELECT_BIG_RESULT) ||
(select && select->quick &&
select->quick->get_type() ==
QUICK_SELECT_I::QS_TYPE_GROUP_MIN_MAX)) &&
(const_tables == table_count ||
((simple_order || skip_sort_order) &&
(made_call=true) &&
test_if_skip_sort_order(&join_tab[const_tables], order,
select_limit, 0,
&join_tab[const_tables].table->
keys_in_use_for_query))))
order=0;
if (made_call)
join_tab[const_tables].update_explain_data(const_tables);
order=0;
if (made_call)
join_tab[const_tables].update_explain_data(const_tables);
}
having= tmp_having;
select_describe(this, need_tmp,
order != 0 && !skip_sort_order,
@ -12022,7 +12040,8 @@ static void update_depend_map_for_order(JOIN *join, ORDER *order)
order->used= 0;
// Not item_sum(), RAND() and no reference to table outside of sub select
if (!(order->depend_map & (OUTER_REF_TABLE_BIT | RAND_TABLE_BIT))
&& !order->item[0]->with_sum_func)
&& !order->item[0]->with_sum_func &&
join->join_tab)
{
for (JOIN_TAB **tab=join->map2table;
depend_map ;
@ -12050,7 +12069,8 @@ static void update_depend_map_for_order(JOIN *join, ORDER *order)
@param cond WHERE statement
@param change_list Set to 1 if we should remove things from list.
If this is not set, then only simple_order is
calculated.
calculated. This is not set when we
are using ROLLUP
@param simple_order Set to 1 if we are only using simple
expressions.
@ -12062,6 +12082,7 @@ static ORDER *
remove_const(JOIN *join,ORDER *first_order, COND *cond,
bool change_list, bool *simple_order)
{
*simple_order= 1;
if (join->table_count == join->const_tables)
return change_list ? 0 : first_order; // No need to sort
@ -12072,23 +12093,37 @@ remove_const(JOIN *join,ORDER *first_order, COND *cond,
bool first_is_base_table= FALSE;
DBUG_ENTER("remove_const");
if (join->join_tab[join->const_tables].table)
{
first_table= join->join_tab[join->const_tables].table->map;
first_is_base_table= TRUE;
}
/*
Cleanup to avoid interference of calls of this function for
ORDER BY and GROUP BY
Join tab is set after make_join_statistics() has been called.
In case of one table with GROUP BY this function is called before
join_tab is set for the GROUP_BY expression
*/
for (JOIN_TAB *tab= join->join_tab + join->const_tables;
tab < join->join_tab + join->table_count;
tab++)
tab->cached_eq_ref_table= FALSE;
if (join->join_tab)
{
if (join->join_tab[join->const_tables].table)
{
first_table= join->join_tab[join->const_tables].table->map;
first_is_base_table= TRUE;
}
/*
Cleanup to avoid interference of calls of this function for
ORDER BY and GROUP BY
*/
for (JOIN_TAB *tab= join->join_tab + join->const_tables;
tab < join->join_tab + join->table_count;
tab++)
tab->cached_eq_ref_table= FALSE;
*simple_order= *join->join_tab[join->const_tables].on_expr_ref ? 0 : 1;
}
else
{
first_is_base_table= FALSE;
first_table= 0; // Not used, for gcc
}
prev_ptr= &first_order;
*simple_order= *join->join_tab[join->const_tables].on_expr_ref ? 0 : 1;
/* NOTE: A variable of not_const_tables ^ first_table; breaks gcc 2.7 */
@ -12134,7 +12169,8 @@ remove_const(JOIN *join,ORDER *first_order, COND *cond,
DBUG_PRINT("info",("removing: %s", order->item[0]->full_name()));
continue;
}
if (first_is_base_table && (ref=order_tables & (not_const_tables ^ first_table)))
if (first_is_base_table &&
(ref=order_tables & (not_const_tables ^ first_table)))
{
if (!(order_tables & first_table) &&
only_eq_ref_tables(join,first_order, ref))
@ -12165,6 +12201,10 @@ remove_const(JOIN *join,ORDER *first_order, COND *cond,
*prev_ptr=0;
if (prev_ptr == &first_order) // Nothing to sort/group
*simple_order=1;
#ifndef DBUG_OFF
if (join->thd->is_error())
DBUG_PRINT("error",("Error from remove_const"));
#endif
DBUG_PRINT("exit",("simple_order: %d",(int) *simple_order));
DBUG_RETURN(first_order);
}
@ -20985,6 +21025,8 @@ create_sort_index(THD *thd, JOIN *join, ORDER *order,
and thus force sorting on disk unless a group min-max optimization
is going to be used as it is applied now only for one table queries
with covering indexes.
The expections is if we are already using the index for GROUP BY
(in which case sort would be free) or ORDER and GROUP BY are different.
*/
if ((order != join->group_list ||
!(join->select_options & SELECT_BIG_RESULT) ||

1
sql/sql_select.h
View File

@ -1327,6 +1327,7 @@ public:
table_count= 0;
top_join_tab_count= 0;
const_tables= 0;
const_table_map= 0;
eliminated_tables= 0;
join_list= 0;
implicit_grouping= FALSE;