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MDEV-6768 Wrong result with aggregate with join with no result set

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When a query does implicit grouping and join operation produces an empty
result set, a NULL-complemented row combination is generated.
However, constant table fields still show non-NULL values.

What happens in the is that end_send_group() is called with a
const row but without any rows matching the WHERE clause.
This last part is shown by 'join->first_record' not being set.

This causes item->no_rows_in_result() to be called for all items to reset
all sum functions to their initial state. However fields are not set
to NULL.

The used fix is to produce NULL-complemented records for constant tables
as well. Also, reset the constant table's records back in case we're
in a subquery which may get re-executed.
An alternative fix would have item->no_rows_in_result() also work
with Item_field objects.

There is some other issues with the code:
- join->no_rows_in_result_called is used but never set.
- Tables that are used with group functions are not properly marked as
  maybe_null, which is required if the table rows should be regarded as
  null-complemented (not existing).
- The code that tries to detect if mixed_implicit_grouping should be set
  didn't take into account all usage of fields and sum functions.
- Item_func::restore_to_before_no_rows_in_result() called the wrong
  function.
- join->clear() does not use a table_map argument to clear_tables(),
  which caused it to ignore constant tables.
- unclear_tables() does not correctly restore status to what is
  was before clear_tables().

Main bug fix was to always use a table_map argument to clear_tables() and
always use join->clear() and clear_tables() together with unclear_tables().

Other fixes:
- Fixed Item_func::restore_to_before_no_rows_in_result()
- Set 'join->no_rows_in_result_called' when no_rows_in_result_set()
  is called.
- Removed not used argument from setup_end_select_func().
- More code comments
- Ensure that end_send_group() modifies the same fields as are in the
  result set.
- Changed return_zero_rows() to use pointers instead of references,
  similar to the rest of the code.

Reviewer: Sergei Petrunia <sergey@mariadb.com>
This commit is contained in:
Monty
2023-03-31 19:35:04 +03:00
parent c0adb05b30
commit 16258677b3
8 changed files with 397 additions and 107 deletions
Download Patch File Download Diff File Expand all files Collapse all files

110
mysql-test/main/group_min_max.result
View File

@ -4095,5 +4095,115 @@ MIN(pk) a
5 10
DROP TABLE t1;
#
# MDEV-6768 Wrong result with agregate with join with no resultset
#
create table t1
(
PARENT_ID int(10) unsigned NOT NULL AUTO_INCREMENT,
PARENT_FIELD VARCHAR(10),
PRIMARY KEY (PARENT_ID)
) engine=innodb;
create table t2
(
CHILD_ID INT NOT NULL AUTO_INCREMENT,
PARENT_ID INT NOT NULL,
CHILD_FIELD varchar(10),
PRIMARY KEY (CHILD_ID)
)engine=innodb;
INSERT INTO t1 (PARENT_FIELD)
SELECT 'AAAA';
INSERT INTO t2 (PARENT_ID, CHILD_FIELD)
SELECT 1, 'BBBB';
explain select
t1.PARENT_ID,
min(CHILD_FIELD)
from t1 straight_join t2
where t1.PARENT_ID = 1
and t1.PARENT_ID = t2.PARENT_ID
and t2.CHILD_FIELD = "ZZZZ";
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 const PRIMARY PRIMARY 4 const 1 Using index
1 SIMPLE t2 ALL NULL NULL NULL NULL 1 Using where
select
t1.PARENT_ID,
min(CHILD_FIELD)
from t1 straight_join t2
where t1.PARENT_ID = 1
and t1.PARENT_ID = t2.PARENT_ID
and t2.CHILD_FIELD = "ZZZZ";
PARENT_ID min(CHILD_FIELD)
NULL NULL
select
1,
min(CHILD_FIELD)
from t1 straight_join t2
where t1.PARENT_ID = 1
and t1.PARENT_ID = t2.PARENT_ID
and t2.CHILD_FIELD = "ZZZZ";
1 min(CHILD_FIELD)
1 NULL
select
IFNULL(t1.PARENT_ID,1),
min(CHILD_FIELD)
from t1 straight_join t2
where t1.PARENT_ID = 1
and t1.PARENT_ID = t2.PARENT_ID
and t2.CHILD_FIELD = "ZZZZ";
IFNULL(t1.PARENT_ID,1) min(CHILD_FIELD)
1 NULL
# Check that things works with MyISAM (which has different explain)
alter table t1 engine=myisam;
alter table t2 engine=myisam;
explain select
t1.PARENT_ID,
min(CHILD_FIELD)
from t1 straight_join t2
where t1.PARENT_ID = 1
and t1.PARENT_ID = t2.PARENT_ID
and t2.CHILD_FIELD = "ZZZZ";
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE NULL NULL NULL NULL NULL NULL NULL Impossible WHERE noticed after reading const tables
select
t1.PARENT_ID,
min(CHILD_FIELD)
from t1 straight_join t2
where t1.PARENT_ID = 1
and t1.PARENT_ID = t2.PARENT_ID
and t2.CHILD_FIELD = "ZZZZ";
PARENT_ID min(CHILD_FIELD)
NULL NULL
drop table t1,t2;
# Check that things works if sub queries are re-executed
create table t1 (a int primary key, b int);
create table t2 (a int primary key, b int);
create table t3 (a int primary key, b int);
insert into t1 values (1,1),(2,2),(3,3);
insert into t2 values (1,1),(2,2),(3,3);
insert into t3 values (1,1),(3,3);
explain
select *,
(select
CONCAT('t2:', IFNULL(t2.a, 't2a-null'), ';',
'min_t3_b:', IFNULL(min(t3.b), 't3b-null'))
from t2,t3
where t2.a=1 and t1.b = t3.a) as s1
from t1;
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY t1 ALL NULL NULL NULL NULL 3
2 DEPENDENT SUBQUERY t2 const PRIMARY PRIMARY 4 const 1 Using index
2 DEPENDENT SUBQUERY t3 eq_ref PRIMARY PRIMARY 4 test.t1.b 1
select *,
(select
CONCAT('t2:', IFNULL(t2.a, 't2a-null'), ';',
'min_t3_b:', IFNULL(min(t3.b), 't3b-null'))
from t2,t3
where t2.a=1 and t1.b = t3.a) as s1
from t1;
a b s1
1 1 t2:1;min_t3_b:1
2 2 t2:t2a-null;min_t3_b:t3b-null
3 3 t2:1;min_t3_b:3
drop table t1,t2,t3;
#
# End of 10.5 tests
#

110
mysql-test/main/group_min_max.test
View File

@ -1748,6 +1748,116 @@ SELECT MIN(pk), a FROM t1 WHERE pk <> 1 GROUP BY a;
DROP TABLE t1;
--echo #
--echo # MDEV-6768 Wrong result with agregate with join with no resultset
--echo #
create table t1
(
PARENT_ID int(10) unsigned NOT NULL AUTO_INCREMENT,
PARENT_FIELD VARCHAR(10),
PRIMARY KEY (PARENT_ID)
) engine=innodb;
create table t2
(
CHILD_ID INT NOT NULL AUTO_INCREMENT,
PARENT_ID INT NOT NULL,
CHILD_FIELD varchar(10),
PRIMARY KEY (CHILD_ID)
)engine=innodb;
INSERT INTO t1 (PARENT_FIELD)
SELECT 'AAAA';
INSERT INTO t2 (PARENT_ID, CHILD_FIELD)
SELECT 1, 'BBBB';
explain select
t1.PARENT_ID,
min(CHILD_FIELD)
from t1 straight_join t2
where t1.PARENT_ID = 1
and t1.PARENT_ID = t2.PARENT_ID
and t2.CHILD_FIELD = "ZZZZ";
select
t1.PARENT_ID,
min(CHILD_FIELD)
from t1 straight_join t2
where t1.PARENT_ID = 1
and t1.PARENT_ID = t2.PARENT_ID
and t2.CHILD_FIELD = "ZZZZ";
select
1,
min(CHILD_FIELD)
from t1 straight_join t2
where t1.PARENT_ID = 1
and t1.PARENT_ID = t2.PARENT_ID
and t2.CHILD_FIELD = "ZZZZ";
select
IFNULL(t1.PARENT_ID,1),
min(CHILD_FIELD)
from t1 straight_join t2
where t1.PARENT_ID = 1
and t1.PARENT_ID = t2.PARENT_ID
and t2.CHILD_FIELD = "ZZZZ";
--echo # Check that things works with MyISAM (which has different explain)
alter table t1 engine=myisam;
alter table t2 engine=myisam;
explain select
t1.PARENT_ID,
min(CHILD_FIELD)
from t1 straight_join t2
where t1.PARENT_ID = 1
and t1.PARENT_ID = t2.PARENT_ID
and t2.CHILD_FIELD = "ZZZZ";
select
t1.PARENT_ID,
min(CHILD_FIELD)
from t1 straight_join t2
where t1.PARENT_ID = 1
and t1.PARENT_ID = t2.PARENT_ID
and t2.CHILD_FIELD = "ZZZZ";
drop table t1,t2;
--echo # Check that things works if sub queries are re-executed
create table t1 (a int primary key, b int);
create table t2 (a int primary key, b int);
create table t3 (a int primary key, b int);
insert into t1 values (1,1),(2,2),(3,3);
insert into t2 values (1,1),(2,2),(3,3);
insert into t3 values (1,1),(3,3);
explain
select *,
(select
CONCAT('t2:', IFNULL(t2.a, 't2a-null'), ';',
'min_t3_b:', IFNULL(min(t3.b), 't3b-null'))
from t2,t3
where t2.a=1 and t1.b = t3.a) as s1
from t1;
select *,
(select
CONCAT('t2:', IFNULL(t2.a, 't2a-null'), ';',
'min_t3_b:', IFNULL(min(t3.b), 't3b-null'))
from t2,t3
where t2.a=1 and t1.b = t3.a) as s1
from t1;
drop table t1,t2,t3;
--echo #
--echo # End of 10.5 tests
--echo #

2
mysql-test/main/type_timestamp.result
View File

@ -1230,6 +1230,8 @@ SELECT * FROM t1 HAVING MIN(t1.c1) >= ALL(SELECT 'a' UNION SELECT 'r');
c1
Warnings:
Warning 1292 Truncated incorrect datetime value: 'r'
SELECT * FROM t1 HAVING MIN(t1.c1) > 0;
c1
DROP TABLE t1;
CREATE TABLE t1 (c1 timestamp);
INSERT INTO t1 VALUES ('2010-01-01 00:00:00');

1
mysql-test/main/type_timestamp.test
View File

@ -810,6 +810,7 @@ DROP TABLE t1;
CREATE TABLE t1 (c1 timestamp);
SELECT MIN(t1.c1) AS k1 FROM t1 HAVING (k1 >= ALL(SELECT 'a' UNION SELECT 'r'));
SELECT * FROM t1 HAVING MIN(t1.c1) >= ALL(SELECT 'a' UNION SELECT 'r');
SELECT * FROM t1 HAVING MIN(t1.c1) > 0;
DROP TABLE t1;
CREATE TABLE t1 (c1 timestamp);

2
sql/item_func.h
View File

@ -380,7 +380,7 @@ public:
{
for (uint i= 0; i < arg_count; i++)
{
args[i]->no_rows_in_result();
args[i]->restore_to_before_no_rows_in_result();
}
}
void convert_const_compared_to_int_field(THD *thd);

238
sql/sql_select.cc
View File

@ -141,10 +141,10 @@ static void update_depend_map_for_order(JOIN *join, ORDER *order);
static ORDER *remove_const(JOIN *join,ORDER *first_order,COND *cond,
bool change_list, bool *simple_order);
static int return_zero_rows(JOIN *join, select_result *res,
List<TABLE_LIST> &tables,
List<Item> &fields, bool send_row,
List<TABLE_LIST> *tables,
List<Item> *fields, bool send_row,
ulonglong select_options, const char *info,
Item *having, List<Item> &all_fields);
Item *having, List<Item> *all_fields);
static COND *build_equal_items(JOIN *join, COND *cond,
COND_EQUAL *inherited,
List<TABLE_LIST> *join_list,
@ -1165,11 +1165,40 @@ int SELECT_LEX::vers_setup_conds(THD *thd, TABLE_LIST *tables)
DBUG_RETURN(0);
}
/*****************************************************************************
Check fields, find best join, do the select and output fields.
mysql_select assumes that all tables are already opened
*****************************************************************************/
/*
Check if we have a field reference. If yes, we have to use
mixed_implicit_grouping.
*/
static bool check_list_for_field(List<Item> *items)
{
List_iterator_fast <Item> select_it(*items);
Item *select_el;
while ((select_el= select_it++))
{
if (select_el->with_field)
return true;
}
return false;
}
static bool check_list_for_field(ORDER *order)
{
for (; order; order= order->next)
{
if (order->item[0]->with_field)
return true;
}
return false;
}
/**
Prepare of whole select (including sub queries in future).
@ -1248,52 +1277,44 @@ JOIN::prepare(TABLE_LIST *tables_init, COND *conds_init, uint og_num,
DBUG_RETURN(-1);
/*
TRUE if the SELECT list mixes elements with and without grouping,
and there is no GROUP BY clause. Mixing non-aggregated fields with
aggregate functions in the SELECT list is a MySQL extenstion that
is allowed only if the ONLY_FULL_GROUP_BY sql mode is not set.
mixed_implicit_grouping will be set to TRUE if the SELECT list
mixes elements with and without grouping, and there is no GROUP BY
clause.
Mixing non-aggregated fields with aggregate functions in the
SELECT list or HAVING is a MySQL extension that is allowed only if
the ONLY_FULL_GROUP_BY sql mode is not set.
*/
mixed_implicit_grouping= false;
if ((~thd->variables.sql_mode & MODE_ONLY_FULL_GROUP_BY) &&
select_lex->with_sum_func && !group_list)
{
List_iterator_fast <Item> select_it(fields_list);
Item *select_el; /* Element of the SELECT clause, can be an expression. */
bool found_field_elem= false;
bool found_sum_func_elem= false;
while ((select_el= select_it++))
if (check_list_for_field(&fields_list) ||
check_list_for_field(order))
{
if (select_el->with_sum_func())
found_sum_func_elem= true;
if (select_el->with_field)
found_field_elem= true;
if (found_sum_func_elem && found_field_elem)
{
mixed_implicit_grouping= true;
break;
}
}
}
table_count= select_lex->leaf_tables.elements;
TABLE_LIST *tbl;
List_iterator_fast<TABLE_LIST> li(select_lex->leaf_tables);
mixed_implicit_grouping= true; // mark for future
while ((tbl= li++))
{
/*
If the query uses implicit grouping where the select list contains both
aggregate functions and non-aggregate fields, any non-aggregated field
may produce a NULL value. Set all fields of each table as nullable before
semantic analysis to take into account this change of nullability.
If the query uses implicit grouping where the select list
contains both aggregate functions and non-aggregate fields,
any non-aggregated field may produce a NULL value. Set all
fields of each table as nullable before semantic analysis to
take into account this change of nullability.
Note: this loop doesn't touch tables inside merged semi-joins, because
subquery-to-semijoin conversion has not been done yet. This is intended.
Note: this loop doesn't touch tables inside merged
semi-joins, because subquery-to-semijoin conversion has not
been done yet. This is intended.
*/
if (mixed_implicit_grouping && tbl->table)
if (tbl->table)
tbl->table->maybe_null= 1;
}
}
}
table_count= select_lex->leaf_tables.elements;
uint real_og_num= og_num;
if (skip_order_by &&
@ -3838,7 +3859,7 @@ bool JOIN::make_aggr_tables_info()
set_items_ref_array(items0);
if (join_tab)
join_tab[exec_join_tab_cnt() + aggr_tables - 1].next_select=
setup_end_select_func(this, NULL);
setup_end_select_func(this);
group= has_group_by;
DBUG_RETURN(false);
@ -4216,13 +4237,7 @@ JOIN::reinit()
}
}
/* Reset of sum functions */
if (sum_funcs)
{
Item_sum *func, **func_ptr= sum_funcs;
while ((func= *(func_ptr++)))
func->clear();
}
clear_sum_funcs();
if (no_rows_in_result_called)
{
@ -4507,12 +4522,12 @@ void JOIN::exec_inner()
}
else
{
(void) return_zero_rows(this, result, select_lex->leaf_tables,
*columns_list,
(void) return_zero_rows(this, result, &select_lex->leaf_tables,
columns_list,
send_row_on_empty_set(),
select_options,
zero_result_cause,
having ? having : tmp_having, all_fields);
having ? having : tmp_having, &all_fields);
DBUG_VOID_RETURN;
}
}
@ -14768,10 +14783,36 @@ ORDER *simple_remove_const(ORDER *order, COND *where)
}
/*
Set all fields in the table to have a null value
@param tables Table list
*/
static void make_tables_null_complemented(List<TABLE_LIST> *tables)
{
List_iterator<TABLE_LIST> ti(*tables);
TABLE_LIST *table;
while ((table= ti++))
{
/*
Don't touch semi-join materialization tables, as the a join_free()
call may have freed them (and HAVING clause can't have references to
them anyway).
*/
if (!table->is_jtbm())
{
TABLE *tbl= table->table;
mark_as_null_row(tbl); // Set fields to NULL
}
}
}
static int
return_zero_rows(JOIN *join, select_result *result, List<TABLE_LIST> &tables,
List<Item> &fields, bool send_row, ulonglong select_options,
const char *info, Item *having, List<Item> &all_fields)
return_zero_rows(JOIN *join, select_result *result, List<TABLE_LIST> *tables,
List<Item> *fields, bool send_row, ulonglong select_options,
const char *info, Item *having, List<Item> *all_fields)
{
DBUG_ENTER("return_zero_rows");
@ -14787,24 +14828,15 @@ return_zero_rows(JOIN *join, select_result *result, List<TABLE_LIST> &tables,
Set all tables to have NULL row. This is needed as we will be evaluating
HAVING condition.
*/
List_iterator<TABLE_LIST> ti(tables);
TABLE_LIST *table;
while ((table= ti++))
{
/*
Don't touch semi-join materialization tables, as the above join_free()
call has freed them (and HAVING clause can't have references to them
anyway).
*/
if (!table->is_jtbm())
mark_as_null_row(table->table); // All fields are NULL
}
List_iterator_fast<Item> it(all_fields);
make_tables_null_complemented(tables);
List_iterator_fast<Item> it(*all_fields);
Item *item;
/*
Inform all items (especially aggregating) to calculate HAVING correctly,
also we will need it for sending results.
*/
join->no_rows_in_result_called= 1;
while ((item= it++))
item->no_rows_in_result();
if (having && having->val_int() == 0)
@ -14818,12 +14850,12 @@ return_zero_rows(JOIN *join, select_result *result, List<TABLE_LIST> &tables,
join->thd->limit_found_rows= 0;
}
if (!(result->send_result_set_metadata(fields,
if (!(result->send_result_set_metadata(*fields,
Protocol::SEND_NUM_ROWS | Protocol::SEND_EOF)))
{
bool send_error= FALSE;
if (send_row)
send_error= result->send_data_with_check(fields, join->unit, 0) > 0;
send_error= result->send_data_with_check(*fields, join->unit, 0) > 0;
if (likely(!send_error))
result->send_eof(); // Should be safe
}
@ -14839,31 +14871,25 @@ return_zero_rows(JOIN *join, select_result *result, List<TABLE_LIST> &tables,
}
/**
used only in JOIN::clear (always) and in do_select()
(if there where no matching rows)
Reset table rows to contain a null-complement row (all fields are null)
Used only in JOIN::clear() and in do_select() if there where no matching rows.
@param join JOIN
@param cleared_tables If not null, clear also const tables and mark all
cleared tables in the map. cleared_tables is only
set when called from do_select() when there is a
group function and there where no matching rows.
@param cleared_tables Used to mark all cleared tables in the map. Needed for
unclear_tables() to know which tables to restore to
their original state.
*/
static void clear_tables(JOIN *join, table_map *cleared_tables)
{
/*
must clear only the non-const tables as const tables are not re-calculated.
*/
DBUG_ASSERT(cleared_tables);
for (uint i= 0 ; i < join->table_count ; i++)
{
TABLE *table= join->table[i];
if (table->null_row)
continue; // Nothing more to do
if (!(table->map & join->const_table_map) || cleared_tables)
{
if (cleared_tables)
{
(*cleared_tables)|= (((table_map) 1) << i);
if (table->s->null_bytes)
{
@ -14873,15 +14899,14 @@ static void clear_tables(JOIN *join, table_map *cleared_tables)
*/
memcpy(table->record[1], table->null_flags, table->s->null_bytes);
}
}
mark_as_null_row(table); // All fields are NULL
}
}
}
/**
Reverse null marking for tables and restore null bits.
This return the tables to the state of before clear_tables().
We have to do this because the tables may be re-used in a sub query
and the subquery will assume that the const tables contains the original
@ -20519,9 +20544,9 @@ void set_postjoin_aggr_write_func(JOIN_TAB *tab)
end_select function to use. This function can't fail.
*/
Next_select_func setup_end_select_func(JOIN *join, JOIN_TAB *tab)
Next_select_func setup_end_select_func(JOIN *join)
{
TMP_TABLE_PARAM *tmp_tbl= tab ? tab->tmp_table_param : &join->tmp_table_param;
TMP_TABLE_PARAM *tmp_tbl= &join->tmp_table_param;
/*
Choose method for presenting result to user. Use end_send_group
@ -20591,7 +20616,7 @@ do_select(JOIN *join, Procedure *procedure)
join->duplicate_rows= join->send_records=0;
if (join->only_const_tables() && !join->need_tmp)
{
Next_select_func end_select= setup_end_select_func(join, NULL);
Next_select_func end_select= setup_end_select_func(join);
/*
HAVING will be checked after processing aggregate functions,
@ -21077,6 +21102,7 @@ sub_select(JOIN *join,JOIN_TAB *join_tab,bool end_of_records)
}
}
/* Restore state if mark_as_null_row() have been called */
if (join_tab->last_inner)
{
JOIN_TAB *last_inner_tab= join_tab->last_inner;
@ -22461,11 +22487,18 @@ end_send_group(JOIN *join, JOIN_TAB *join_tab __attribute__((unused)),
{
int idx= -1;
enum_nested_loop_state ok_code= NESTED_LOOP_OK;
/*
join_tab can be 0 in the case all tables are const tables and we did not
need a temporary table to store the result.
In this case we use the original given fields, which is stored in
join->fields.
*/
List<Item> *fields= join_tab ? (join_tab-1)->fields : join->fields;
DBUG_ENTER("end_send_group");
if (!join->items3.is_null() && !join->set_group_rpa)
{
/* Move ref_pointer_array to points to items3 */
join->set_group_rpa= true;
join->set_items_ref_array(join->items3);
}
@ -22473,10 +22506,12 @@ end_send_group(JOIN *join, JOIN_TAB *join_tab __attribute__((unused)),
if (!join->first_record || end_of_records ||
(idx=test_if_group_changed(join->group_fields)) >= 0)
{
if (!join->group_sent &&
(join->first_record ||
(end_of_records && !join->group && !join->group_optimized_away)))
{
table_map cleared_tables= (table_map) 0;
if (join->procedure)
join->procedure->end_group();
if (idx < (int) join->send_group_parts)
@ -22499,11 +22534,13 @@ end_send_group(JOIN *join, JOIN_TAB *join_tab __attribute__((unused)),
{
if (!join->first_record)
{
List_iterator_fast<Item> it(*join->fields);
Item *item;
/* No matching rows for group function */
join->clear();
List_iterator_fast<Item> it(*fields);
Item *item;
join->no_rows_in_result_called= 1;
join->clear(&cleared_tables);
while ((item= it++))
item->no_rows_in_result();
}
@ -22531,6 +22568,13 @@ end_send_group(JOIN *join, JOIN_TAB *join_tab __attribute__((unused)),
if (join->rollup_send_data((uint) (idx+1)))
error= 1;
}
if (join->no_rows_in_result_called)
{
/* Restore null tables to original state */
join->no_rows_in_result_called= 0;
if (cleared_tables)
unclear_tables(join, &cleared_tables);
}
}
if (unlikely(error > 0))
DBUG_RETURN(NESTED_LOOP_ERROR); /* purecov: inspected */
@ -22835,6 +22879,7 @@ end_write_group(JOIN *join, JOIN_TAB *join_tab __attribute__((unused)),
{
if (join->first_record || (end_of_records && !join->group))
{
table_map cleared_tables= (table_map) 0;
if (join->procedure)
join->procedure->end_group();
int send_group_parts= join->send_group_parts;
@ -22843,7 +22888,7 @@ end_write_group(JOIN *join, JOIN_TAB *join_tab __attribute__((unused)),
if (!join->first_record)
{
/* No matching rows for group function */
join->clear();
join->clear(&cleared_tables);
}
copy_sum_funcs(join->sum_funcs,
join->sum_funcs_end[send_group_parts]);
@ -22866,6 +22911,8 @@ end_write_group(JOIN *join, JOIN_TAB *join_tab __attribute__((unused)),
DBUG_RETURN(NESTED_LOOP_ERROR);
}
}
if (cleared_tables)
unclear_tables(join, &cleared_tables);
if (end_of_records)
goto end;
}
@ -26965,11 +27012,8 @@ int JOIN::rollup_write_data(uint idx, TMP_TABLE_PARAM *tmp_table_param_arg, TABL
(end_send_group/end_write_group)
*/
void JOIN::clear()
void inline JOIN::clear_sum_funcs()
{
clear_tables(this, 0);
copy_fields(&tmp_table_param);
if (sum_funcs)
{
Item_sum *func, **func_ptr= sum_funcs;
@ -26979,6 +27023,22 @@ void JOIN::clear()
}
/*
Prepare for returning 'empty row' when there is no matching row.
- Mark all tables with mark_as_null_row()
- Make a copy of of all simple SELECT items
- Reset all sum functions to NULL or 0.
*/
void JOIN::clear(table_map *cleared_tables)
{
clear_tables(this, cleared_tables);
copy_fields(&tmp_table_param);
clear_sum_funcs();
}
/**
Print an EXPLAIN line with all NULLs and given message in the 'Extra' column

5
sql/sql_select.h
View File

@ -227,7 +227,7 @@ enum sj_strategy_enum
typedef enum_nested_loop_state
(*Next_select_func)(JOIN *, struct st_join_table *, bool);
Next_select_func setup_end_select_func(JOIN *join, JOIN_TAB *tab);
Next_select_func setup_end_select_func(JOIN *join);
int rr_sequential(READ_RECORD *info);
int rr_sequential_and_unpack(READ_RECORD *info);
Item *remove_pushed_top_conjuncts(THD *thd, Item *cond);
@ -1767,7 +1767,8 @@ public:
void join_free();
/** Cleanup this JOIN, possibly for reuse */
void cleanup(bool full);
void clear();
void clear(table_map *cleared_tables);
void inline clear_sum_funcs();
bool send_row_on_empty_set()
{
return (do_send_rows && implicit_grouping && !group_optimized_away &&

8
sql/table.h
View File

@ -3306,10 +3306,16 @@ inline void mark_as_null_row(TABLE *table)
bfill(table->null_flags,table->s->null_bytes,255);
}
/*
Restore table to state before mark_as_null_row() call.
This assumes that the caller has restored table->null_flags,
as is done in unclear_tables().
*/
inline void unmark_as_null_row(TABLE *table)
{
table->null_row= 0;
table->status= STATUS_NO_RECORD;
table->status&= ~STATUS_NULL_ROW;
}
bool is_simple_order(ORDER *order);