mariadb/mysql-test/r/limit_rows_examined.result

set @save_join_cache_level = @@join_cache_level;
create table t1 (c1 char(2));
create table t2 (c2 char(2));
insert into t1 values ('bb'), ('cc'), ('aa'), ('dd');
insert into t2 values ('bb'), ('cc'), ('dd'), ('ff');
create table t1i (c1 char(2) key);
create table t2i (c2 char(2) key);
insert into t1i values ('bb'), ('cc'), ('aa'), ('dd');
insert into t2i values ('bb'), ('cc'), ('dd'), ('ff');
=========================================================================
Simple joins
=========================================================================
Simple nested loops join without blocking
set @@join_cache_level=0;
explain
select * from t1, t2 where c1 = c2 LIMIT ROWS EXAMINED 2;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	4	
1	SIMPLE	t2	ALL	NULL	NULL	NULL	NULL	4	Using where
select * from t1, t2 where c1 = c2 LIMIT ROWS EXAMINED 2;
c1	c2
bb	bb
Warnings:
Warning	1931	Query execution was interrupted. The query examined at least 3 rows, which exceeds LIMIT ROWS EXAMINED (2). The query result may be incomplete.
explain
select * from t1i, t2i where c1 = c2 LIMIT ROWS EXAMINED 4;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	SIMPLE	t1i	index	PRIMARY	PRIMARY	2	NULL	4	Using index
1	SIMPLE	t2i	eq_ref	PRIMARY	PRIMARY	2	test.t1i.c1	1	Using index
select * from t1i, t2i where c1 = c2 LIMIT ROWS EXAMINED 4;
c1	c2
bb	bb
Warnings:
Warning	1931	Query execution was interrupted. The query examined at least 5 rows, which exceeds LIMIT ROWS EXAMINED (4). The query result may be incomplete.
Blocked nested loops join, empty result set because of blocking
set @@join_cache_level=1;
explain
select * from t1, t2 where c1 = c2 LIMIT ROWS EXAMINED 6;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	4	
1	SIMPLE	t2	ALL	NULL	NULL	NULL	NULL	4	Using where; Using join buffer (flat, BNL join)
select * from t1, t2 where c1 = c2 LIMIT ROWS EXAMINED 6;
c1	c2
bb	bb
Warnings:
Warning	1931	Query execution was interrupted. The query examined at least 7 rows, which exceeds LIMIT ROWS EXAMINED (6). The query result may be incomplete.
explain
select * from t1i, t2i where c1 = c2 LIMIT ROWS EXAMINED 6;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	SIMPLE	t1i	index	PRIMARY	PRIMARY	2	NULL	4	Using index
1	SIMPLE	t2i	index	PRIMARY	PRIMARY	2	NULL	4	Using where; Using index; Using join buffer (flat, BNL join)
select * from t1i, t2i where c1 = c2 LIMIT ROWS EXAMINED 6;
c1	c2
bb	bb
Warnings:
Warning	1931	Query execution was interrupted. The query examined at least 7 rows, which exceeds LIMIT ROWS EXAMINED (6). The query result may be incomplete.
set @@join_cache_level=6;
explain
select * from t1, t2 where c1 = c2 LIMIT ROWS EXAMINED 3;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	4	Using where
1	SIMPLE	t2	hash_ALL	NULL	#hash#$hj	3	test.t1.c1	4	Using where; Using join buffer (flat, BNLH join)
select * from t1, t2 where c1 = c2 LIMIT ROWS EXAMINED 3;
c1	c2
Warnings:
Warning	1931	Query execution was interrupted. The query examined at least 4 rows, which exceeds LIMIT ROWS EXAMINED (3). The query result may be incomplete.
explain
select * from t1i, t2i where c1 = c2 LIMIT ROWS EXAMINED 6;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	SIMPLE	t1i	index	PRIMARY	PRIMARY	2	NULL	4	Using index
1	SIMPLE	t2i	index	PRIMARY	PRIMARY	2	NULL	4	Using where; Using index; Using join buffer (flat, BNL join)
select * from t1i, t2i where c1 = c2 LIMIT ROWS EXAMINED 6;
c1	c2
bb	bb
Warnings:
Warning	1931	Query execution was interrupted. The query examined at least 7 rows, which exceeds LIMIT ROWS EXAMINED (6). The query result may be incomplete.
Mix LIMIT ROWS EXAMINED with LIMIT
set @@join_cache_level=0;
explain
select * from t1, t2 where c1 < c2 LIMIT 1 ROWS EXAMINED 4;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	4	
1	SIMPLE	t2	ALL	NULL	NULL	NULL	NULL	4	Using where
select * from t1, t2 where c1 < c2 LIMIT 1 ROWS EXAMINED 4;
c1	c2
bb	cc
explain
select * from t1, t2 where c1 < c2 LIMIT 1,1 ROWS EXAMINED 4;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	4	
1	SIMPLE	t2	ALL	NULL	NULL	NULL	NULL	4	Using where
select * from t1, t2 where c1 < c2 LIMIT 1,1 ROWS EXAMINED 4;
c1	c2
bb	dd
Empty table optimized away during constant optimization
create table t0 (c0 int);
explain
select * from t0 LIMIT ROWS EXAMINED 0;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	SIMPLE	t0	system	NULL	NULL	NULL	NULL	0	const row not found
explain
select * from t0 LIMIT ROWS EXAMINED 1;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	SIMPLE	t0	system	NULL	NULL	NULL	NULL	0	const row not found
select * from t0 LIMIT ROWS EXAMINED 1;
c0
drop table t0;
create table t0 (c0 char(2) primary key);
insert into t0 values  ('bb'), ('cc'), ('aa');
explain
select * from t0 where c0 = 'bb' LIMIT ROWS EXAMINED 0;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	SIMPLE	t0	const	PRIMARY	PRIMARY	2	const	1	Using index
select * from t0 where c0 = 'bb' LIMIT ROWS EXAMINED 0;
c0
bb
explain
select * from t0, t1 where c0 = 'bb' and c1 > c0 LIMIT ROWS EXAMINED 0;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	SIMPLE	t0	const	PRIMARY	PRIMARY	2	const	1	Using index
1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	4	Using where
select * from t0, t1 where c0 = 'bb' and c1 > c0 LIMIT ROWS EXAMINED 0;
c0	c1
Warnings:
Warning	1931	Query execution was interrupted. The query examined at least 2 rows, which exceeds LIMIT ROWS EXAMINED (0). The query result may be incomplete.
set @@join_cache_level = @save_join_cache_level;
drop table t0;
=========================================================================
LIMIT ROWS EXAMINED with parameter argument
=========================================================================
set @@join_cache_level=0;
set @l = 2;
Prepared statement parameter
prepare st1 from "select * from t1, t2 where c1 = c2 LIMIT ROWS EXAMINED ?";
execute st1 using @l;
c1	c2
bb	bb
Warnings:
Warning	1931	Query execution was interrupted. The query examined at least 3 rows, which exceeds LIMIT ROWS EXAMINED (2). The query result may be incomplete.
deallocate prepare st1;
User variable (not supported for LIMIT in MariaDB 5.3/MySQL 5.1)
select * from t1, t2 where c1 = c2 LIMIT ROWS EXAMINED @l;
ERROR 42000: You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near '@l' at line 1
Stored procedure parameter
create procedure test_limit_rows(l int)
begin
select * from t1, t2 where c1 = c2 LIMIT ROWS EXAMINED l;
end|
call test_limit_rows(3);
c1	c2
bb	bb
Warnings:
Warning	1931	Query execution was interrupted. The query examined at least 4 rows, which exceeds LIMIT ROWS EXAMINED (3). The query result may be incomplete.
drop procedure test_limit_rows;
set @@join_cache_level = @save_join_cache_level;
=========================================================================
UNIONs (with several LIMIT ROWS EXAMINED clauses)
=========================================================================
(select * from t1, t2 where c1 = c2)
UNION
(select * from t1, t2 where c1 < c2) LIMIT ROWS EXAMINED 6;
c1	c2
bb	bb
Warnings:
Warning	1931	Query execution was interrupted. The query examined at least 8 rows, which exceeds LIMIT ROWS EXAMINED (6). The query result may be incomplete.
(select * from t1, t2 where c1 = c2 LIMIT ROWS EXAMINED 0)
UNION
(select * from t1, t2 where c1 < c2 LIMIT ROWS EXAMINED 6);
c1	c2
bb	bb
Warnings:
Warning	1931	Query execution was interrupted. The query examined at least 8 rows, which exceeds LIMIT ROWS EXAMINED (6). The query result may be incomplete.
select * from t1, t2 where c1 = c2 LIMIT ROWS EXAMINED 0
UNION
select * from t1, t2 where c1 < c2 LIMIT ROWS EXAMINED 6;
ERROR 42000: You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near 'UNION
select * from t1, t2 where c1 < c2 LIMIT ROWS EXAMINED 6' at line 2
(select * from t1, t2 where c1 = c2 LIMIT ROWS EXAMINED 0)
UNION
(select * from t1, t2 where c1 < c2 LIMIT ROWS EXAMINED 0)
LIMIT ROWS EXAMINED 6;
c1	c2
bb	bb
Warnings:
Warning	1931	Query execution was interrupted. The query examined at least 8 rows, which exceeds LIMIT ROWS EXAMINED (6). The query result may be incomplete.
(select * from t1, t2 where c1 = c2 LIMIT ROWS EXAMINED 0)
UNION
(select * from t1, t2 where c1 < c2 LIMIT ROWS EXAMINED 0)
LIMIT 1 ROWS EXAMINED 6;
c1	c2
bb	bb
Warnings:
Warning	1931	Query execution was interrupted. The query examined at least 8 rows, which exceeds LIMIT ROWS EXAMINED (6). The query result may be incomplete.
(select * from t1, t2 where c1 = c2 LIMIT ROWS EXAMINED 0)
UNION
(select * from t1, t2 where c1 < c2 LIMIT ROWS EXAMINED 0)
LIMIT 2 ROWS EXAMINED 10;
c1	c2
bb	bb
cc	cc
Warnings:
Warning	1931	Query execution was interrupted. The query examined at least 12 rows, which exceeds LIMIT ROWS EXAMINED (10). The query result may be incomplete.
=========================================================================
Subqueries (with several LIMIT ROWS EXAMINED clauses)
=========================================================================
Subqueries, semi-join
explain
select * from t1
where c1 IN (select * from t2 where c2 > ' ' LIMIT ROWS EXAMINED 11);
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	PRIMARY	t1	ALL	NULL	NULL	NULL	NULL	4	
1	PRIMARY	<subquery2>	eq_ref	distinct_key	distinct_key	2	func	1	
2	MATERIALIZED	t2	ALL	NULL	NULL	NULL	NULL	4	Using where
select * from t1
where c1 IN (select * from t2 where c2 > ' ' LIMIT ROWS EXAMINED 11);
c1
bb
Warnings:
Warning	1931	Query execution was interrupted. The query examined at least 12 rows, which exceeds LIMIT ROWS EXAMINED (11). The query result may be incomplete.
explain
select * from t1
where c1 IN (select * from t2 where c2 > ' ')
LIMIT ROWS EXAMINED 11;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	PRIMARY	t1	ALL	NULL	NULL	NULL	NULL	4	
1	PRIMARY	<subquery2>	eq_ref	distinct_key	distinct_key	2	func	1	
2	MATERIALIZED	t2	ALL	NULL	NULL	NULL	NULL	4	Using where
select * from t1
where c1 IN (select * from t2 where c2 > ' ')
LIMIT ROWS EXAMINED 11;
c1
bb
Warnings:
Warning	1931	Query execution was interrupted. The query examined at least 12 rows, which exceeds LIMIT ROWS EXAMINED (11). The query result may be incomplete.
explain
select * from t1
where c1 IN (select * from t2 where c2 > ' ' LIMIT ROWS EXAMINED 0)
LIMIT ROWS EXAMINED 11;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	PRIMARY	t1	ALL	NULL	NULL	NULL	NULL	4	
1	PRIMARY	<subquery2>	eq_ref	distinct_key	distinct_key	2	func	1	
2	MATERIALIZED	t2	ALL	NULL	NULL	NULL	NULL	4	Using where
select * from t1
where c1 IN (select * from t2 where c2 > ' ' LIMIT ROWS EXAMINED 0)
LIMIT ROWS EXAMINED 11;
c1
bb
Warnings:
Warning	1931	Query execution was interrupted. The query examined at least 12 rows, which exceeds LIMIT ROWS EXAMINED (11). The query result may be incomplete.
explain
select * from t1i
where c1 IN (select * from t2i where c2 > ' ')
LIMIT ROWS EXAMINED 6;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	PRIMARY	t1i	index	PRIMARY	PRIMARY	2	NULL	4	Using where; Using index
1	PRIMARY	t2i	index	PRIMARY	PRIMARY	2	NULL	4	Using where; Using index; Using join buffer (flat, BNL join)
select * from t1i
where c1 IN (select * from t2i where c2 > ' ')
LIMIT ROWS EXAMINED 6;
c1
bb
Warnings:
Warning	1931	Query execution was interrupted. The query examined at least 7 rows, which exceeds LIMIT ROWS EXAMINED (6). The query result may be incomplete.
Subqueries with IN-TO-EXISTS
set @@optimizer_switch='semijoin=off,in_to_exists=on,materialization=off';
explain
select * from t1
where c1 IN (select * from t2 where c2 > ' ' LIMIT ROWS EXAMINED 4);
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	PRIMARY	t1	ALL	NULL	NULL	NULL	NULL	4	Using where
2	DEPENDENT SUBQUERY	t2	ALL	NULL	NULL	NULL	NULL	4	Using where
select * from t1
where c1 IN (select * from t2 where c2 > ' ' LIMIT ROWS EXAMINED 4);
c1
bb
Warnings:
Warning	1931	Query execution was interrupted. The query examined at least 5 rows, which exceeds LIMIT ROWS EXAMINED (4). The query result may be incomplete.
explain
select * from t1
where c1 IN (select * from t2 where c2 > ' ')
LIMIT ROWS EXAMINED 4;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	PRIMARY	t1	ALL	NULL	NULL	NULL	NULL	4	Using where
2	DEPENDENT SUBQUERY	t2	ALL	NULL	NULL	NULL	NULL	4	Using where
select * from t1
where c1 IN (select * from t2 where c2 > ' ')
LIMIT ROWS EXAMINED 4;
c1
bb
Warnings:
Warning	1931	Query execution was interrupted. The query examined at least 5 rows, which exceeds LIMIT ROWS EXAMINED (4). The query result may be incomplete.
explain
select * from t1
where c1 IN (select * from t2 where c2 > ' ' LIMIT ROWS EXAMINED 0)
LIMIT ROWS EXAMINED 4;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	PRIMARY	t1	ALL	NULL	NULL	NULL	NULL	4	Using where
2	DEPENDENT SUBQUERY	t2	ALL	NULL	NULL	NULL	NULL	4	Using where
select * from t1
where c1 IN (select * from t2 where c2 > ' ' LIMIT ROWS EXAMINED 0)
LIMIT ROWS EXAMINED 4;
c1
bb
Warnings:
Warning	1931	Query execution was interrupted. The query examined at least 5 rows, which exceeds LIMIT ROWS EXAMINED (4). The query result may be incomplete.
explain
select * from t1i
where c1 IN (select * from t2i where c2 > ' ')
LIMIT ROWS EXAMINED 9;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	PRIMARY	t1i	index	NULL	PRIMARY	2	NULL	4	Using where; Using index
2	DEPENDENT SUBQUERY	t2i	unique_subquery	PRIMARY	PRIMARY	2	func	1	Using index; Using where
select * from t1i
where c1 IN (select * from t2i where c2 > ' ')
LIMIT ROWS EXAMINED 9;
c1
bb
Warnings:
Warning	1931	Query execution was interrupted. The query examined at least 12 rows, which exceeds LIMIT ROWS EXAMINED (9). The query result may be incomplete.
Same as above, without subquery cache
set @@optimizer_switch='subquery_cache=off';
select * from t1
where c1 IN (select * from t2 where c2 > ' ' LIMIT ROWS EXAMINED 2);
c1
bb
Warnings:
Warning	1931	Query execution was interrupted. The query examined at least 3 rows, which exceeds LIMIT ROWS EXAMINED (2). The query result may be incomplete.
select * from t1
where c1 IN (select * from t2 where c2 > ' ')
LIMIT ROWS EXAMINED 2;
c1
bb
Warnings:
Warning	1931	Query execution was interrupted. The query examined at least 3 rows, which exceeds LIMIT ROWS EXAMINED (2). The query result may be incomplete.
select * from t1
where c1 IN (select * from t2 where c2 > ' ' LIMIT ROWS EXAMINED 0)
LIMIT ROWS EXAMINED 2;
c1
bb
Warnings:
Warning	1931	Query execution was interrupted. The query examined at least 3 rows, which exceeds LIMIT ROWS EXAMINED (2). The query result may be incomplete.
select * from t1i
where c1 IN (select * from t2i where c2 > ' ')
LIMIT ROWS EXAMINED 5;
c1
bb
Warnings:
Warning	1931	Query execution was interrupted. The query examined at least 7 rows, which exceeds LIMIT ROWS EXAMINED (5). The query result may be incomplete.
Subqueries with materialization
set @@optimizer_switch='semijoin=off,in_to_exists=off,materialization=on,subquery_cache=on';
explain
select * from t1
where c1 IN (select * from t2 where c2 > ' ' LIMIT ROWS EXAMINED 13);
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	PRIMARY	t1	ALL	NULL	NULL	NULL	NULL	4	Using where
2	MATERIALIZED	t2	ALL	NULL	NULL	NULL	NULL	4	Using where
select * from t1
where c1 IN (select * from t2 where c2 > ' ' LIMIT ROWS EXAMINED 13);
c1
bb
Warnings:
Warning	1931	Query execution was interrupted. The query examined at least 14 rows, which exceeds LIMIT ROWS EXAMINED (13). The query result may be incomplete.
explain
select * from t1
where c1 IN (select * from t2 where c2 > ' ') LIMIT ROWS EXAMINED 13;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	PRIMARY	t1	ALL	NULL	NULL	NULL	NULL	4	Using where
2	MATERIALIZED	t2	ALL	NULL	NULL	NULL	NULL	4	Using where
select * from t1
where c1 IN (select * from t2 where c2 > ' ') LIMIT ROWS EXAMINED 13;
c1
bb
Warnings:
Warning	1931	Query execution was interrupted. The query examined at least 14 rows, which exceeds LIMIT ROWS EXAMINED (13). The query result may be incomplete.
explain
select * from t1
where c1 IN (select * from t2 where c2 > ' ' LIMIT ROWS EXAMINED 0)
LIMIT ROWS EXAMINED 13;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	PRIMARY	t1	ALL	NULL	NULL	NULL	NULL	4	Using where
2	MATERIALIZED	t2	ALL	NULL	NULL	NULL	NULL	4	Using where
select * from t1
where c1 IN (select * from t2 where c2 > ' ' LIMIT ROWS EXAMINED 0)
LIMIT ROWS EXAMINED 13;
c1
bb
Warnings:
Warning	1931	Query execution was interrupted. The query examined at least 14 rows, which exceeds LIMIT ROWS EXAMINED (13). The query result may be incomplete.
explain
select * from t1i
where c1 IN (select * from t2i where c2 > ' ') LIMIT ROWS EXAMINED 17;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	PRIMARY	t1i	index	NULL	PRIMARY	2	NULL	4	Using where; Using index
2	MATERIALIZED	t2i	index	PRIMARY	PRIMARY	2	NULL	4	Using where; Using index
select * from t1i
where c1 IN (select * from t2i where c2 > ' ') LIMIT ROWS EXAMINED 17;
c1
bb
Warnings:
Warning	1931	Query execution was interrupted. The query examined at least 18 rows, which exceeds LIMIT ROWS EXAMINED (17). The query result may be incomplete.
set @@optimizer_switch='default';
=========================================================================
Views and derived tables
=========================================================================
create view v1 as
select * from t1 where c1 IN (select * from t2 where c2 > ' ' LIMIT ROWS EXAMINED 13);
ERROR 42000: This version of MariaDB doesn't yet support 'LIMIT ROWS EXAMINED inside views'
create view v1 as
select * from t1 where c1 IN (select * from t2 where c2 > ' ');
select * from v1;
c1
bb
cc
dd
select * from v1 LIMIT ROWS EXAMINED 17;
c1
bb
cc
dd
Warnings:
Warning	1931	Query execution was interrupted. The query examined at least 18 rows, which exceeds LIMIT ROWS EXAMINED (17). The query result may be incomplete.
select * from v1 LIMIT ROWS EXAMINED 16;
c1
bb
cc
Warnings:
Warning	1931	Query execution was interrupted. The query examined at least 18 rows, which exceeds LIMIT ROWS EXAMINED (16). The query result may be incomplete.
select * from v1 LIMIT ROWS EXAMINED 11;
c1
bb
Warnings:
Warning	1931	Query execution was interrupted. The query examined at least 12 rows, which exceeds LIMIT ROWS EXAMINED (11). The query result may be incomplete.
drop view v1;
explain
select *
from (select * from t1
where c1 IN (select * from t2 where c2 > ' ' LIMIT ROWS EXAMINED 0)) as tmp
LIMIT ROWS EXAMINED 11;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	PRIMARY	t1	ALL	NULL	NULL	NULL	NULL	4	Using where
3	MATERIALIZED	t2	ALL	NULL	NULL	NULL	NULL	4	Using where
select *
from (select * from t1
where c1 IN (select * from t2 where c2 > ' ' LIMIT ROWS EXAMINED 0)) as tmp
LIMIT ROWS EXAMINED 11;
c1
bb
Warnings:
Warning	1931	Query execution was interrupted. The query examined at least 12 rows, which exceeds LIMIT ROWS EXAMINED (11). The query result may be incomplete.
=========================================================================
Aggregation
=========================================================================
create table t3 (c1 char(2), c2 int);
insert into t3 values
('aa', 1), ('aa', 2),
('bb', 3), ('bb', 4), ('bb', 5);
explain
select c1, sum(c2) from t3 group by c1;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	SIMPLE	t3	ALL	NULL	NULL	NULL	NULL	5	Using temporary; Using filesort
select c1, sum(c2) from t3 group by c1;
c1	sum(c2)
aa	3
bb	12
explain
select c1, sum(c2) from t3 group by c1 LIMIT ROWS EXAMINED 0;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	SIMPLE	t3	ALL	NULL	NULL	NULL	NULL	5	Using temporary; Using filesort
select c1, sum(c2) from t3 group by c1 LIMIT ROWS EXAMINED 0;
c1	sum(c2)
Warnings:
Warning	1931	Query execution was interrupted. The query examined at least 1 rows, which exceeds LIMIT ROWS EXAMINED (0). The query result may be incomplete.
select c1, sum(c2) from t3 group by c1 LIMIT ROWS EXAMINED 1;
c1	sum(c2)
Warnings:
Warning	1931	Query execution was interrupted. The query examined at least 3 rows, which exceeds LIMIT ROWS EXAMINED (1). The query result may be incomplete.
select c1, sum(c2) from t3 group by c1 LIMIT ROWS EXAMINED 20;
c1	sum(c2)
aa	3
Warnings:
Warning	1931	Query execution was interrupted. The query examined at least 21 rows, which exceeds LIMIT ROWS EXAMINED (20). The query result may be incomplete.
select c1, sum(c2) from t3 group by c1 LIMIT ROWS EXAMINED 21;
c1	sum(c2)
aa	3
bb	12
create table t3i (c1 char(2), c2 int);
create index it3i on t3i(c1);
create index it3j on t3i(c2,c1);
insert into t3i values
('aa', 1), ('aa', 2),
('bb', 3), ('bb', 4), ('bb', 5);
explain
select c1, sum(c2) from t3i group by c1 LIMIT ROWS EXAMINED 0;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	SIMPLE	t3i	index	NULL	it3j	8	NULL	5	Using index; Using temporary; Using filesort
select c1, sum(c2) from t3i group by c1 LIMIT ROWS EXAMINED 0;
c1	sum(c2)
Warnings:
Warning	1931	Query execution was interrupted. The query examined at least 1 rows, which exceeds LIMIT ROWS EXAMINED (0). The query result may be incomplete.
select c1, sum(c2) from t3i group by c1 LIMIT ROWS EXAMINED 1;
c1	sum(c2)
Warnings:
Warning	1931	Query execution was interrupted. The query examined at least 3 rows, which exceeds LIMIT ROWS EXAMINED (1). The query result may be incomplete.
select c1, sum(c2) from t3i group by c1 LIMIT ROWS EXAMINED 20;
c1	sum(c2)
aa	3
Warnings:
Warning	1931	Query execution was interrupted. The query examined at least 21 rows, which exceeds LIMIT ROWS EXAMINED (20). The query result may be incomplete.
select c1, sum(c2) from t3i group by c1 LIMIT ROWS EXAMINED 21;
c1	sum(c2)
aa	3
bb	12
Aggregation without grouping
explain
select min(c2) from t3 LIMIT ROWS EXAMINED 5;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	SIMPLE	t3	ALL	NULL	NULL	NULL	NULL	5	
select min(c2) from t3 LIMIT ROWS EXAMINED 5;
min(c2)
Warnings:
Warning	1931	Query execution was interrupted. The query examined at least 6 rows, which exceeds LIMIT ROWS EXAMINED (5). The query result may be incomplete.
select max(c2) from t3 LIMIT ROWS EXAMINED 6;
max(c2)
5
select max(c2) from t3 LIMIT ROWS EXAMINED 0;
max(c2)
Warnings:
Warning	1931	Query execution was interrupted. The query examined at least 1 rows, which exceeds LIMIT ROWS EXAMINED (0). The query result may be incomplete.
explain
select max(c2) from t3 where c2 > 10 LIMIT ROWS EXAMINED 5;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	SIMPLE	t3	ALL	NULL	NULL	NULL	NULL	5	Using where
select max(c2) from t3 where c2 > 10 LIMIT ROWS EXAMINED 5;
max(c2)
Warnings:
Warning	1931	Query execution was interrupted. The query examined at least 6 rows, which exceeds LIMIT ROWS EXAMINED (5). The query result may be incomplete.
select max(c2) from t3 where c2 > 10 LIMIT ROWS EXAMINED 6;
max(c2)
NULL
select max(c2) from t3 where c2 > 10 LIMIT ROWS EXAMINED 0;
max(c2)
Warnings:
Warning	1931	Query execution was interrupted. The query examined at least 1 rows, which exceeds LIMIT ROWS EXAMINED (0). The query result may be incomplete.
explain
select count(c2) from t3 LIMIT ROWS EXAMINED 5;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	SIMPLE	t3	ALL	NULL	NULL	NULL	NULL	5	
select count(c2) from t3 LIMIT ROWS EXAMINED 5;
count(c2)
Warnings:
Warning	1931	Query execution was interrupted. The query examined at least 6 rows, which exceeds LIMIT ROWS EXAMINED (5). The query result may be incomplete.
select count(c2) from t3 LIMIT ROWS EXAMINED 6;
count(c2)
5
select count(c2) from t3 LIMIT ROWS EXAMINED 0;
count(c2)
Warnings:
Warning	1931	Query execution was interrupted. The query examined at least 1 rows, which exceeds LIMIT ROWS EXAMINED (0). The query result may be incomplete.
explain
select count(c2) from t3 where c2 > 10 LIMIT ROWS EXAMINED 5;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	SIMPLE	t3	ALL	NULL	NULL	NULL	NULL	5	Using where
select count(c2) from t3 where c2 > 10 LIMIT ROWS EXAMINED 5;
count(c2)
Warnings:
Warning	1931	Query execution was interrupted. The query examined at least 6 rows, which exceeds LIMIT ROWS EXAMINED (5). The query result may be incomplete.
select count(c2) from t3 where c2 > 10 LIMIT ROWS EXAMINED 6;
count(c2)
0
explain
select sum(c2) from t3 LIMIT ROWS EXAMINED 5;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	SIMPLE	t3	ALL	NULL	NULL	NULL	NULL	5	
select sum(c2) from t3 LIMIT ROWS EXAMINED 5;
sum(c2)
Warnings:
Warning	1931	Query execution was interrupted. The query examined at least 6 rows, which exceeds LIMIT ROWS EXAMINED (5). The query result may be incomplete.
select sum(c2) from t3 LIMIT ROWS EXAMINED 6;
sum(c2)
15
The query result is found during optimization, LIMIT ROWS EXAMINED has no effect.
explain
select max(c1) from t3i LIMIT ROWS EXAMINED 0;
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
select max(c1) from t3i LIMIT ROWS EXAMINED 0;
max(c1)
bb
create table t3_empty like t3;
explain
select max(c1) from t3_empty LIMIT ROWS EXAMINED 0;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	SIMPLE	t3_empty	system	NULL	NULL	NULL	NULL	0	const row not found
select max(c1) from t3_empty LIMIT ROWS EXAMINED 0;
max(c1)
NULL
drop table t3_empty;
=========================================================================
Sorting
=========================================================================
explain
select c1, c2 from t3 order by c2, c1 LIMIT ROWS EXAMINED 2;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	SIMPLE	t3	ALL	NULL	NULL	NULL	NULL	5	Using filesort
select c1, c2 from t3 order by c2, c1 LIMIT ROWS EXAMINED 2;
ERROR HY000: Sort aborted: 
explain
select c1, c2 from t3i order by c2, c1 LIMIT ROWS EXAMINED 2;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	SIMPLE	t3i	index	NULL	it3j	8	NULL	5	Using index
select c1, c2 from t3i order by c2, c1 LIMIT ROWS EXAMINED 2;
c1	c2
aa	1
aa	2
Warnings:
Warning	1931	Query execution was interrupted. The query examined at least 3 rows, which exceeds LIMIT ROWS EXAMINED (2). The query result may be incomplete.
explain
select c1, c2 from t3i order by c2, c1 desc LIMIT ROWS EXAMINED 2;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	SIMPLE	t3i	index	NULL	it3j	8	NULL	5	Using index; Using filesort
select c1, c2 from t3i order by c2, c1 desc LIMIT ROWS EXAMINED 2;
ERROR HY000: Sort aborted: 
drop table t3,t3i;
=========================================================================
INSERT/DELETE/UPDATE
=========================================================================
INSERT ... SELECT
CREATE TABLE t4 (a int);
INSERT INTO t4 values (1), (2);
INSERT INTO t4 SELECT a + 2 FROM t4 LIMIT ROWS EXAMINED 0;
Warnings:
Warning	1931	Query execution was interrupted. The query examined at least 1 rows, which exceeds LIMIT ROWS EXAMINED (0). The query result may be incomplete.
select * from t4;
a
1
2
INSERT INTO t4 SELECT a + 2 FROM t4 LIMIT ROWS EXAMINED 6;
Warnings:
Warning	1931	Query execution was interrupted. The query examined at least 8 rows, which exceeds LIMIT ROWS EXAMINED (6). The query result may be incomplete.
select * from t4;
a
1
2
3
drop table t4;
DELETE - LIMIT ROWS EXAMINED not supported
CREATE TABLE t4 (a int);
INSERT INTO t4 values (1), (2);
DELETE FROM t4 WHERE t4.a > 0 LIMIT ROWS EXAMINED 0;
ERROR 42000: You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near 'EXAMINED 0' at line 1
DELETE FROM t4 WHERE t4.a > 0 LIMIT 0 ROWS EXAMINED 0;
ERROR 42000: You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near 'EXAMINED 0' at line 1
drop table t4;
UPDATE - LIMIT ROWS EXAMINED not supported
CREATE TABLE t4 (a int);
INSERT INTO t4 values (1), (2);
update t4 set a=a+10 LIMIT ROWS EXAMINED 0;
ERROR 42000: You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near 'EXAMINED 0' at line 1
update t4 set a=a+10 LIMIT 0 ROWS EXAMINED 0;
ERROR 42000: You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near 'EXAMINED 0' at line 1
drop table t4;
drop table t1,t2,t1i,t2i;
=========================================================================
Test cases for bugs
=========================================================================

MDEV-115

SET @@optimizer_switch='in_to_exists=on,outer_join_with_cache=on';
CREATE TABLE t1 ( a VARCHAR(3) ) ENGINE=MyISAM;
INSERT INTO t1 VALUES ('USA'),('CAN');
CREATE TABLE t2 ( b INT );
INSERT INTO t2 VALUES (3899),(3914),(3888);
CREATE TABLE t3 ( c VARCHAR(33), d INT );
INSERT INTO t3 VALUES ('USASpanish',8),('USATagalog',0),('USAVietnamese',0);
EXPLAIN
SELECT DISTINCT a AS field1 FROM t1, t2 
WHERE EXISTS (SELECT c FROM t3 LEFT JOIN t2 ON b = d) 
HAVING field1 > 'aaa' LIMIT ROWS EXAMINED 20;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	PRIMARY	t1	ALL	NULL	NULL	NULL	NULL	2	Using temporary
1	PRIMARY	t2	ALL	NULL	NULL	NULL	NULL	3	Using join buffer (flat, BNL join)
2	SUBQUERY	t3	ALL	NULL	NULL	NULL	NULL	3	
2	SUBQUERY	t2	ALL	NULL	NULL	NULL	NULL	3	Using where; Using join buffer (flat, BNL join)
SELECT DISTINCT a AS field1 FROM t1, t2 
WHERE EXISTS (SELECT c FROM t3 LEFT JOIN t2 ON b = d) 
HAVING field1 > 'aaa' LIMIT ROWS EXAMINED 20;
field1
Warnings:
Warning	1931	Query execution was interrupted. The query examined at least 21 rows, which exceeds LIMIT ROWS EXAMINED (20). The query result may be incomplete.
EXPLAIN
SELECT DISTINCT a FROM t1, t2  HAVING a > ' ' LIMIT ROWS EXAMINED 14;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	2	Using temporary
1	SIMPLE	t2	ALL	NULL	NULL	NULL	NULL	3	Using join buffer (flat, BNL join)
SELECT DISTINCT a FROM t1, t2  HAVING a > ' ' LIMIT ROWS EXAMINED 14;
a
USA
Warnings:
Warning	1931	Query execution was interrupted. The query examined at least 15 rows, which exceeds LIMIT ROWS EXAMINED (14). The query result may be incomplete.
SELECT DISTINCT a FROM t1, t2  HAVING a > ' ' LIMIT ROWS EXAMINED 15;
a
USA
CAN
Warnings:
Warning	1931	Query execution was interrupted. The query examined at least 16 rows, which exceeds LIMIT ROWS EXAMINED (15). The query result may be incomplete.
SELECT DISTINCT a FROM t1, t2  HAVING a > ' ' LIMIT ROWS EXAMINED 16;
a
USA
CAN
Warnings:
Warning	1931	Query execution was interrupted. The query examined at least 17 rows, which exceeds LIMIT ROWS EXAMINED (16). The query result may be incomplete.
drop table t1,t2,t3;
set @@optimizer_switch='default';

MDEV-153

CREATE TABLE t1 ( a TIME, b DATETIME, KEY(a), KEY(b) ) ENGINE=MyISAM;
INSERT INTO t1 VALUES 
('21:22:34.025509', '2002-02-13 17:30:06.013935'), 
('10:50:38.059966', '2008-09-27 00:34:58.026613'), 
('00:21:38.058143', '2007-05-28 00:00:00');
CREATE TABLE t2 ( c INT, d TIME, e DATETIME, f VARCHAR(1), KEY(c) ) ENGINE=MyISAM;
INSERT INTO t2 VALUES
(0, '11:03:22.062907', '2007-06-02 11:16:01.053212', 'a'), 
(0, '08:14:05.001407', '1900-01-01 00:00:00', 'm'), 
(5, '19:03:16.024974', '1900-01-01 00:00:00', 'f'), 
(1, '07:23:34.034234', '2000-11-26 05:01:11.054228', 'z'), 
(6, '12:29:32.019411', '2006-02-13 00:00:00', 'f'), 
(6, '06:07:10.010496', '2007-06-08 04:35:26.020373', 'a'), 
(7, '22:55:09.020772', '2005-04-27 00:00:00', 'i');
EXPLAIN
SELECT a AS field1, alias2.d AS field2, alias2.f AS field3, alias2.e AS field4, b AS field5
FROM t1, t2 AS alias2, t2 AS alias3 
WHERE alias3.c IN ( SELECT 1 UNION SELECT 6 ) 
GROUP BY field1, field2, field3, field4, field5
LIMIT ROWS EXAMINED 120;
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	PRIMARY	t1	ALL	NULL	NULL	NULL	NULL	3	Using temporary; Using filesort
1	PRIMARY	alias2	ALL	NULL	NULL	NULL	NULL	7	Using join buffer (flat, BNL join)
1	PRIMARY	alias3	index	NULL	c	5	NULL	7	Using where; Using index; Using join buffer (incremental, BNL join)
2	DEPENDENT SUBQUERY	NULL	NULL	NULL	NULL	NULL	NULL	NULL	No tables used
3	DEPENDENT UNION	NULL	NULL	NULL	NULL	NULL	NULL	NULL	No tables used
NULL	UNION RESULT	<union2,3>	ALL	NULL	NULL	NULL	NULL	NULL	
FLUSH STATUS;
SELECT a AS field1, alias2.d AS field2, alias2.f AS field3, alias2.e AS field4, b AS field5
FROM t1, t2 AS alias2, t2 AS alias3 
WHERE alias3.c IN ( SELECT 1 UNION SELECT 6 ) 
GROUP BY field1, field2, field3, field4, field5
LIMIT ROWS EXAMINED 120;
ERROR HY000: Sort aborted: 
SHOW STATUS LIKE 'Handler_read%';
Variable_name	Value
Handler_read_first	0
Handler_read_key	5
Handler_read_last	0
Handler_read_next	0
Handler_read_prev	0
Handler_read_retry	0
Handler_read_rnd	0
Handler_read_rnd_deleted	0
Handler_read_rnd_next	46
SHOW STATUS LIKE 'Handler_tmp%';
Variable_name	Value
Handler_tmp_update	0
Handler_tmp_write	70
FLUSH STATUS;
SELECT a AS field1, alias2.d AS field2, alias2.f AS field3, alias2.e AS field4, b AS field5
FROM t1, t2 AS alias2, t2 AS alias3 
WHERE alias3.c IN ( SELECT 1 UNION SELECT 6 ) 
GROUP BY field1, field2, field3, field4, field5
LIMIT ROWS EXAMINED 124;
field1	field2	field3	field4	field5
00:21:38	06:07:10	a	2007-06-08 04:35:26	2007-05-28 00:00:00
Warnings:
Warning	1931	Query execution was interrupted. The query examined at least 125 rows, which exceeds LIMIT ROWS EXAMINED (124). The query result may be incomplete.
SHOW STATUS LIKE 'Handler_read%';
Variable_name	Value
Handler_read_first	0
Handler_read_key	5
Handler_read_last	0
Handler_read_next	0
Handler_read_prev	0
Handler_read_retry	0
Handler_read_rnd	2
Handler_read_rnd_deleted	1
Handler_read_rnd_next	47
SHOW STATUS LIKE 'Handler_tmp%';
Variable_name	Value
Handler_tmp_update	0
Handler_tmp_write	70
drop table t1, t2;

MDEV-161 LIMIT_ROWS EXAMINED: query with the limit and NOT EXISTS, without GROUP BY or aggregate,
returns rows, while the same query without the limit returns empty set

CREATE TABLE t1 ( a INT, b INT );
INSERT INTO t1 VALUES (3911,17),(3847,33),(3857,26);
CREATE TABLE t2 ( c VARCHAR(16) );
INSERT INTO t2 VALUES ('English'),('French'),('German');
CREATE TABLE t3 ( d INT, e VARCHAR(32) );
INSERT INTO t3 VALUES (3813,'United States'),(3814,'United States');
SELECT * FROM t1 AS alias1, t2 AS alias2 
WHERE NOT EXISTS (
SELECT * FROM t1 LEFT OUTER JOIN t3 
ON (d = a) 
WHERE b <= alias1.b OR e != alias2.c  
);
a	b	c
SELECT * FROM t1 AS alias1, t2 AS alias2 
WHERE NOT EXISTS ( 
SELECT * FROM t1 LEFT OUTER JOIN t3 
ON (d = a) 
WHERE b <= alias1.b OR e != alias2.c  
) LIMIT ROWS EXAMINED 20;
a	b	c
Warnings:
Warning	1931	Query execution was interrupted. The query examined at least 25 rows, which exceeds LIMIT ROWS EXAMINED (20). The query result may be incomplete.
drop table t1, t2, t3;

MDEV-174: LIMIT ROWS EXAMINED: Assertion `0' failed in net_end_statement(THD*)
with subquery in SELECT, constant table, aggregate function

CREATE TABLE t1 ( a INT );
CREATE TABLE t2 ( b INT, c INT, KEY(c) );
INSERT INTO t2 VALUES 
(5, 0),(3, 4),(6, 1),
(5, 8),(4, 9),(8, 1);
SELECT (SELECT MAX(c) FROM t1, t2)
FROM t2
WHERE c = (SELECT MAX(b) FROM t2)
LIMIT ROWS EXAMINED 3;
(SELECT MAX(c) FROM t1, t2)
Warnings:
Warning	1931	Query execution was interrupted. The query examined at least 10 rows, which exceeds LIMIT ROWS EXAMINED (3). The query result may be incomplete.
drop table t1, t2;

MDEV-178: LIMIT ROWS EXAMINED: Assertion `0' failed in net_end_statement(THD*) on the
2nd PS execution, with DISTINCT, FROM subquery or view in SELECT, JOIN in nested subquery

CREATE TABLE t1 ( a INT );
INSERT INTO t1 VALUES (2),(3),(150);
CREATE TABLE t2 ( b INT );
INSERT INTO t2 VALUES (2),(17),(3),(6);
CREATE VIEW v AS
SELECT DISTINCT * FROM t1 WHERE a > (SELECT COUNT(*) FROM t1, t2 WHERE a = b);
PREPARE ps FROM 'SELECT * FROM v LIMIT ROWS EXAMINED 21';
EXECUTE ps;
a
3
Warnings:
Warning	1931	Query execution was interrupted. The query examined at least 22 rows, which exceeds LIMIT ROWS EXAMINED (21). The query result may be incomplete.
EXECUTE ps;
a
3
Warnings:
Warning	1931	Query execution was interrupted. The query examined at least 22 rows, which exceeds LIMIT ROWS EXAMINED (21). The query result may be incomplete.
drop view v;
drop table t1, t2;