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Commit 64aff71e authored by unknown's avatar unknown
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Bug#24156: Loose index scan not used with CREATE TABLE ...SELECT and similar 

           statements
Currently the optimizer evaluates loose index scan only for top-level SELECT
statements
Extend loose index scan applicability by :
 - Test the applicability of loose scan for each sub-select, instead of the
   whole query. This change enables loose index scan for sub-queries.
 - allow non-select statements with SELECT parts (like, e.g. 
   CREATE TABLE .. SELECT ...) to use loose index scan.


mysql-test/r/group_min_max.result:
  Bug#24156: Loose index scan not used with CREATE TABLE ...SELECT and similar
             statements
   - test case
mysql-test/t/group_min_max.test:
  Bug#24156: Loose index scan not used with CREATE TABLE ...SELECT and similar
             statements
   - test case
sql/opt_range.cc:
  Bug#24156: Loose index scan not used with CREATE TABLE ...SELECT and similar
             statements
   - loose index scan will be tried over the current subselect 
     (lex->current_select) instead of the whole query (lex->select_lex).
   - allow non-select statements with SELECT parts (like, e.g. 
     CREATE TABLE .. SELECT ...) to use loose index scan.
parent d15f779d
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Showing with 187 additions and 3 deletions
mysql-test/r/group_min_max.result
View file @ 64aff71e
......@@ -2162,3 +2162,127 @@ SELECT MIN(c) FROM t2 WHERE b = 2 and a = 1 and c > 1 GROUP BY a;
MIN(c)
2
DROP TABLE t1,t2;
CREATE TABLE t1 (a INT, b INT, INDEX (a,b));
INSERT INTO t1 (a, b) VALUES (1,1), (1,2), (1,3), (1,4), (1,5),
(2,2), (2,3), (2,1), (3,1), (4,1), (4,2), (4,3), (4,4), (4,5), (4,6);
EXPLAIN SELECT max(b), a FROM t1 GROUP BY a;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 range NULL a 5 NULL 8 Using index for group-by
FLUSH STATUS;
SELECT max(b), a FROM t1 GROUP BY a;
max(b) a
5 1
3 2
1 3
6 4
SHOW STATUS LIKE 'handler_read__e%';
Variable_name Value
Handler_read_key 8
Handler_read_next 0
EXPLAIN SELECT max(b), a FROM t1 GROUP BY a;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 range NULL a 5 NULL 8 Using index for group-by
FLUSH STATUS;
CREATE TABLE t2 SELECT max(b), a FROM t1 GROUP BY a;
SHOW STATUS LIKE 'handler_read__e%';
Variable_name Value
Handler_read_key 8
Handler_read_next 0
FLUSH STATUS;
SELECT * FROM (SELECT max(b), a FROM t1 GROUP BY a) b;
max(b) a
5 1
3 2
1 3
6 4
SHOW STATUS LIKE 'handler_read__e%';
Variable_name Value
Handler_read_key 8
Handler_read_next 0
FLUSH STATUS;
(SELECT max(b), a FROM t1 GROUP BY a) UNION
(SELECT max(b), a FROM t1 GROUP BY a);
max(b) a
5 1
3 2
1 3
6 4
SHOW STATUS LIKE 'handler_read__e%';
Variable_name Value
Handler_read_key 16
Handler_read_next 0
EXPLAIN (SELECT max(b), a FROM t1 GROUP BY a) UNION
(SELECT max(b), a FROM t1 GROUP BY a);
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY t1 range NULL a 5 NULL 8 Using index for group-by
2 UNION t1 range NULL a 5 NULL 8 Using index for group-by
NULL UNION RESULT <union1,2> ALL NULL NULL NULL NULL NULL
EXPLAIN SELECT (SELECT max(b) FROM t1 GROUP BY a HAVING a < 2) x
FROM t1 AS t1_outer;
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY t1_outer index NULL a 10 NULL 15 Using index
2 SUBQUERY t1 range NULL a 5 NULL 8 Using index for group-by
EXPLAIN SELECT 1 FROM t1 AS t1_outer WHERE EXISTS
(SELECT max(b) FROM t1 GROUP BY a HAVING a < 2);
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY t1_outer index NULL a 10 NULL 15 Using index
2 SUBQUERY t1 index NULL a 10 NULL 8 Using index
EXPLAIN SELECT 1 FROM t1 AS t1_outer WHERE
(SELECT max(b) FROM t1 GROUP BY a HAVING a < 2) > 12;
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY NULL NULL NULL NULL NULL NULL NULL Impossible WHERE
2 SUBQUERY t1 range NULL a 5 NULL 8 Using index for group-by
EXPLAIN SELECT 1 FROM t1 AS t1_outer WHERE
a IN (SELECT max(b) FROM t1 GROUP BY a HAVING a < 2);
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY t1_outer index NULL a 10 NULL 15 Using where; Using index
2 DEPENDENT SUBQUERY t1 index NULL a 10 NULL 8 Using index
EXPLAIN SELECT 1 FROM t1 AS t1_outer GROUP BY a HAVING
a > (SELECT max(b) FROM t1 GROUP BY a HAVING a < 2);
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY t1_outer range NULL a 5 NULL 8 Using index for group-by
2 SUBQUERY t1 range NULL a 5 NULL 8 Using index for group-by
EXPLAIN SELECT 1 FROM t1 AS t1_outer1 JOIN t1 AS t1_outer2
ON t1_outer1.a = (SELECT max(b) FROM t1 GROUP BY a HAVING a < 2)
AND t1_outer1.b = t1_outer2.b;
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY t1_outer1 ref a a 5 const 1 Using where; Using index
1 PRIMARY t1_outer2 index NULL a 10 NULL 15 Using where; Using index
2 SUBQUERY t1 range NULL a 5 NULL 8 Using index for group-by
EXPLAIN SELECT (SELECT (SELECT max(b) FROM t1 GROUP BY a HAVING a < 2) x
FROM t1 AS t1_outer) x2 FROM t1 AS t1_outer2;
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY t1_outer2 index NULL a 10 NULL 15 Using index
2 SUBQUERY t1_outer index NULL a 10 NULL 15 Using index
3 SUBQUERY t1 range NULL a 5 NULL 8 Using index for group-by
CREATE TABLE t3 LIKE t1;
FLUSH STATUS;
INSERT INTO t3 SELECT a,MAX(b) FROM t1 GROUP BY a;
SHOW STATUS LIKE 'handler_read__e%';
Variable_name Value
Handler_read_key 8
Handler_read_next 0
DELETE FROM t3;
FLUSH STATUS;
INSERT INTO t3 SELECT 1, (SELECT MAX(b) FROM t1 GROUP BY a HAVING a < 2)
FROM t1 LIMIT 1;
SHOW STATUS LIKE 'handler_read__e%';
Variable_name Value
Handler_read_key 8
Handler_read_next 0
FLUSH STATUS;
DELETE FROM t3 WHERE (SELECT MAX(b) FROM t1 GROUP BY a HAVING a < 2) > 10000;
SHOW STATUS LIKE 'handler_read__e%';
Variable_name Value
Handler_read_key 8
Handler_read_next 0
FLUSH STATUS;
DELETE FROM t3 WHERE (SELECT (SELECT MAX(b) FROM t1 GROUP BY a HAVING a < 2) x
FROM t1) > 10000;
Warnings:
Error 1242 Subquery returns more than 1 row
SHOW STATUS LIKE 'handler_read__e%';
Variable_name Value
Handler_read_key 8
Handler_read_next 1
DROP TABLE t1,t2,t3;
mysql-test/t/group_min_max.test
View file @ 64aff71e
......@@ -810,3 +810,63 @@ explain SELECT MIN(c) FROM t2 WHERE b = 2 and a = 1 and c > 1 GROUP BY a;
SELECT MIN(c) FROM t2 WHERE b = 2 and a = 1 and c > 1 GROUP BY a;
DROP TABLE t1,t2;
#
# Bug#24156: Loose index scan not used with CREATE TABLE ...SELECT and similar statements
#
CREATE TABLE t1 (a INT, b INT, INDEX (a,b));
INSERT INTO t1 (a, b) VALUES (1,1), (1,2), (1,3), (1,4), (1,5),
(2,2), (2,3), (2,1), (3,1), (4,1), (4,2), (4,3), (4,4), (4,5), (4,6);
EXPLAIN SELECT max(b), a FROM t1 GROUP BY a;
FLUSH STATUS;
SELECT max(b), a FROM t1 GROUP BY a;
SHOW STATUS LIKE 'handler_read__e%';
EXPLAIN SELECT max(b), a FROM t1 GROUP BY a;
FLUSH STATUS;
CREATE TABLE t2 SELECT max(b), a FROM t1 GROUP BY a;
SHOW STATUS LIKE 'handler_read__e%';
FLUSH STATUS;
SELECT * FROM (SELECT max(b), a FROM t1 GROUP BY a) b;
SHOW STATUS LIKE 'handler_read__e%';
FLUSH STATUS;
(SELECT max(b), a FROM t1 GROUP BY a) UNION
(SELECT max(b), a FROM t1 GROUP BY a);
SHOW STATUS LIKE 'handler_read__e%';
EXPLAIN (SELECT max(b), a FROM t1 GROUP BY a) UNION
(SELECT max(b), a FROM t1 GROUP BY a);
EXPLAIN SELECT (SELECT max(b) FROM t1 GROUP BY a HAVING a < 2) x
FROM t1 AS t1_outer;
EXPLAIN SELECT 1 FROM t1 AS t1_outer WHERE EXISTS
(SELECT max(b) FROM t1 GROUP BY a HAVING a < 2);
EXPLAIN SELECT 1 FROM t1 AS t1_outer WHERE
(SELECT max(b) FROM t1 GROUP BY a HAVING a < 2) > 12;
EXPLAIN SELECT 1 FROM t1 AS t1_outer WHERE
a IN (SELECT max(b) FROM t1 GROUP BY a HAVING a < 2);
EXPLAIN SELECT 1 FROM t1 AS t1_outer GROUP BY a HAVING
a > (SELECT max(b) FROM t1 GROUP BY a HAVING a < 2);
EXPLAIN SELECT 1 FROM t1 AS t1_outer1 JOIN t1 AS t1_outer2
ON t1_outer1.a = (SELECT max(b) FROM t1 GROUP BY a HAVING a < 2)
AND t1_outer1.b = t1_outer2.b;
EXPLAIN SELECT (SELECT (SELECT max(b) FROM t1 GROUP BY a HAVING a < 2) x
FROM t1 AS t1_outer) x2 FROM t1 AS t1_outer2;
CREATE TABLE t3 LIKE t1;
FLUSH STATUS;
INSERT INTO t3 SELECT a,MAX(b) FROM t1 GROUP BY a;
SHOW STATUS LIKE 'handler_read__e%';
DELETE FROM t3;
FLUSH STATUS;
INSERT INTO t3 SELECT 1, (SELECT MAX(b) FROM t1 GROUP BY a HAVING a < 2)
FROM t1 LIMIT 1;
SHOW STATUS LIKE 'handler_read__e%';
FLUSH STATUS;
DELETE FROM t3 WHERE (SELECT MAX(b) FROM t1 GROUP BY a HAVING a < 2) > 10000;
SHOW STATUS LIKE 'handler_read__e%';
FLUSH STATUS;
DELETE FROM t3 WHERE (SELECT (SELECT MAX(b) FROM t1 GROUP BY a HAVING a < 2) x
FROM t1) > 10000;
SHOW STATUS LIKE 'handler_read__e%';
DROP TABLE t1,t2,t3;
sql/opt_range.cc
View file @ 64aff71e
......@@ -7445,7 +7445,7 @@ static TRP_GROUP_MIN_MAX *
get_best_group_min_max(PARAM *param, SEL_TREE *tree)
{
THD *thd= param->thd;
JOIN *join= thd->lex->select_lex.join;
JOIN *join= thd->lex->current_select->join;
TABLE *table= param->table;
bool have_min= FALSE; /* TRUE if there is a MIN function. */
bool have_max= FALSE; /* TRUE if there is a MAX function. */
......@@ -7466,7 +7466,7 @@ get_best_group_min_max(PARAM *param, SEL_TREE *tree)
DBUG_ENTER("get_best_group_min_max");
/* Perform few 'cheap' tests whether this access method is applicable. */
if (!join || (thd->lex->sql_command != SQLCOM_SELECT))
if (!join)
DBUG_RETURN(NULL); /* This is not a select statement. */
if ((join->tables != 1) || /* The query must reference one table. */
((!join->group_list) && /* Neither GROUP BY nor a DISTINCT query. */
......@@ -8316,7 +8316,7 @@ TRP_GROUP_MIN_MAX::make_quick(PARAM *param, bool retrieve_full_rows,
DBUG_ENTER("TRP_GROUP_MIN_MAX::make_quick");
quick= new QUICK_GROUP_MIN_MAX_SELECT(param->table,
param->thd->lex->select_lex.join,
param->thd->lex->current_select->join,
have_min, have_max, min_max_arg_part,
group_prefix_len, used_key_parts,
index_info, index, read_cost, records,
......
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