Commit d3dd6fa0 authored by unknown's avatar unknown
Browse files

Bug #16792 query with subselect, join, and group not returning proper values 

 Treat queries with no FROM and aggregate functions as normal queries,
so the aggregate function get correctly calculated as if there is 1 row. 
This means that they will be considered to have one row, so COUNT(*) will return
1 instead of 0. Other aggregates will behave in compatible manner.


mysql-test/r/func_gconcat.result:
  Bug #16792 query with subselect, join, and group not returning proper values
   - test case. Note how it improves the support for DUAL.
mysql-test/r/func_group.result:
  Bug #16792 query with subselect, join, and group not returning proper values
   - test case. Note how it improves the support for DUAL.
mysql-test/r/subselect.result:
  Bug #16792 query with subselect, join, and group not returning proper values
   - consequence of (SELECT MAX(<const>)) now returning <const> instead of 0
mysql-test/t/func_group.test:
  Bug #16792 query with subselect, join, and group not returning proper values
   - test case.
sql/opt_sum.cc:
  Bug #16792 query with subselect, join, and group not returning proper values
   - cannot do the optimization if the index is already opened by (say) UPDATE
     as it invloves opening reading and closing the index.
sql/sql_select.cc:
  Bug #16792 query with subselect, join, and group not returning proper values
   - Treat queries with no FROM and aggregate functions as normal queries,
  so the aggregate function get correctly calculated as if there is 1 row.
parent 84ece59c

mysql-test/r/func_gconcat.result

+2 −2
Original line number Diff line number Diff line
@@ -559,14 +559,14 @@ COUNT(*) GROUP_CONCAT(DISTINCT t2.somename SEPARATOR ' |') 
DROP TABLE t1,t2;

select * from (select group_concat('c') from DUAL) t;

group_concat('c')

NULL

c

create table t1 ( a int not null default 0);

select * from (select group_concat(a) from t1) t2;

group_concat(a)

NULL

select group_concat('x') UNION ALL select 1;

group_concat('x')

NULL

x

1

drop table t1;

CREATE TABLE t1 (id int, a varchar(9));

mysql-test/r/func_group.result

+20 −4
Original line number Diff line number Diff line
@@ -794,7 +794,7 @@ min(7) 
NULL

select min(7) from DUAL;

min(7)

NULL

7

explain select min(7) from t2m join t1m;

id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra

1	SIMPLE	NULL	NULL	NULL	NULL	NULL	NULL	NULL	Select tables optimized away
@@ -809,7 +809,7 @@ max(7) 
NULL

select max(7) from DUAL;

max(7)

NULL

7

explain select max(7) from t2m join t1m;

id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra

1	SIMPLE	NULL	NULL	NULL	NULL	NULL	NULL	NULL	Select tables optimized away
@@ -848,7 +848,7 @@ min(7) 
NULL

select min(7) from DUAL;

min(7)

NULL

7

explain select min(7) from t2i join t1i;

id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra

1	SIMPLE	t2i	ALL	NULL	NULL	NULL	NULL	1
@@ -864,7 +864,7 @@ max(7) 
NULL

select max(7) from DUAL;

max(7)

NULL

7

explain select max(7) from t2i join t1i;

id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra

1	SIMPLE	t2i	ALL	NULL	NULL	NULL	NULL	1
@@ -942,3 +942,19 @@ EXPLAIN SELECT MAX(b) FROM t1; 
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra

1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	2	

DROP TABLE t1;

CREATE TABLE t1 (a INT, b INT);

INSERT INTO t1 VALUES (1,1),(1,2),(2,3);

SELECT (SELECT COUNT(DISTINCT t1.b)) FROM t1 GROUP BY t1.a;

(SELECT COUNT(DISTINCT t1.b))

1

1

SELECT (SELECT COUNT(DISTINCT 12)) FROM t1 GROUP BY t1.a;

(SELECT COUNT(DISTINCT 12))

1

1

SELECT AVG(2), BIT_AND(2), BIT_OR(2), BIT_XOR(2), COUNT(*), COUNT(12),

COUNT(DISTINCT 12), MIN(2),MAX(2),STD(2), VARIANCE(2),SUM(2),

GROUP_CONCAT(2),GROUP_CONCAT(DISTINCT 2);

AVG(2)	BIT_AND(2)	BIT_OR(2)	BIT_XOR(2)	COUNT(*)	COUNT(12)	COUNT(DISTINCT 12)	MIN(2)	MAX(2)	STD(2)	VARIANCE(2)	SUM(2)	GROUP_CONCAT(2)	GROUP_CONCAT(DISTINCT 2)

2.0000	2	2	2	1	1	1	2	2	0.0000	0.0000	2	2	2

DROP TABLE t1;

mysql-test/r/subselect.result

+2 −2
Original line number Diff line number Diff line
@@ -1001,7 +1001,7 @@ INSERT INTO t1 VALUES (1); 
UPDATE t1 SET i=i+1 WHERE i=(SELECT MAX(i));

select * from t1;

i

1

2

drop table t1;

CREATE TABLE t1 (a int(1));

EXPLAIN EXTENDED SELECT (SELECT RAND() FROM t1) FROM t1;
@@ -1193,7 +1193,7 @@ UPDATE t1 SET t.i=i+(SELECT MAX(i) FROM (SELECT 1) t); 
ERROR 42S02: Unknown table 't' in field list

select * from t1;

i

1

3

drop table t1;

CREATE TABLE t1 (

id int(11) default NULL

mysql-test/t/func_group.test

+14 −0
Original line number Diff line number Diff line
@@ -617,4 +617,18 @@ SELECT MAX(b) FROM t1; 
EXPLAIN SELECT MAX(b) FROM t1;

DROP TABLE t1;



#

# Bug #16792  query with subselect, join, and group not returning proper values

#

CREATE TABLE t1 (a INT, b INT);

INSERT INTO t1 VALUES (1,1),(1,2),(2,3);



SELECT (SELECT COUNT(DISTINCT t1.b)) FROM t1 GROUP BY t1.a;

SELECT (SELECT COUNT(DISTINCT 12)) FROM t1 GROUP BY t1.a;

# an attempt to test all aggregate function with no table.

SELECT AVG(2), BIT_AND(2), BIT_OR(2), BIT_XOR(2), COUNT(*), COUNT(12),

       COUNT(DISTINCT 12), MIN(2),MAX(2),STD(2), VARIANCE(2),SUM(2),

       GROUP_CONCAT(2),GROUP_CONCAT(DISTINCT 2);

DROP TABLE t1;



# End of 4.1 tests

sql/opt_sum.cc

+2 −2
Original line number Diff line number Diff line
@@ -182,7 +182,7 @@ int opt_sum_query(TABLE_LIST *tables, List<Item> &all_fields,COND *conds) 
            Type of range for the key part for this field will be

            returned in range_fl.

          */

          if ((outer_tables & table->map) ||

          if (table->file->inited || (outer_tables & table->map) ||

              !find_key_for_maxmin(0, &ref, item_field->field, conds,

                                   &range_fl, &prefix_len))

          {
@@ -269,7 +269,7 @@ int opt_sum_query(TABLE_LIST *tables, List<Item> &all_fields,COND *conds) 
            Type of range for the key part for this field will be

            returned in range_fl.

          */

          if ((outer_tables & table->map) ||

          if (table->file->inited || (outer_tables & table->map) ||

	          !find_key_for_maxmin(1, &ref, item_field->field, conds,

				                   &range_fl, &prefix_len))

          {