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	- Renamed "Using join cache" to "Using join buffer". - "Using join buffer" is now printed on the last table that "reads" from the join buffer cache.
		
			
				
	
	
		
			658 lines
		
	
	
		
			40 KiB
		
	
	
	
		
			Plaintext
		
	
	
	
	
	
			
		
		
	
	
			658 lines
		
	
	
		
			40 KiB
		
	
	
	
		
			Plaintext
		
	
	
	
	
	
drop table if exists t1,t2,t3,t4,t5,t6,t7;
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create table t1 (
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c11 integer,c12 integer,c13 integer,c14 integer,c15 integer,c16 integer,
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primary key (c11)
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);
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create table t2 (
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c21 integer,c22 integer,c23 integer,c24 integer,c25 integer,c26 integer
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);
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create table t3 (
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c31 integer,c32 integer,c33 integer,c34 integer,c35 integer,c36 integer,
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primary key (c31)
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);
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create table t4 (
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c41 integer,c42 integer,c43 integer,c44 integer,c45 integer,c46 integer
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);
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create table t5 (
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c51 integer,c52 integer,c53 integer,c54 integer,c55 integer,c56 integer,
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primary key (c51)
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);
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create table t6 (
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c61 integer,c62 integer,c63 integer,c64 integer,c65 integer,c66 integer
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);
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create table t7 (
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c71 integer,c72 integer,c73 integer,c74 integer,c75 integer,c76 integer,
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primary key (c71)
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);
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insert into t1 values (1,2,3,4,5,6);
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insert into t1 values (2,2,3,4,5,6);
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insert into t1 values (3,2,3,4,5,6);
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insert into t2 values (1,2,3,4,5,6);
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insert into t2 values (2,2,3,4,5,6);
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insert into t2 values (3,2,3,4,5,6);
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insert into t2 values (4,2,3,4,5,6);
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insert into t2 values (5,2,3,4,5,6);
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insert into t2 values (6,2,3,4,5,6);
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insert into t3 values (1,2,3,4,5,6);
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insert into t3 values (2,2,3,4,5,6);
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insert into t3 values (3,2,3,4,5,6);
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insert into t3 values (4,2,3,4,5,6);
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insert into t3 values (5,2,3,4,5,6);
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insert into t3 values (6,2,3,4,5,6);
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insert into t3 values (7,2,3,4,5,6);
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insert into t3 values (8,2,3,4,5,6);
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insert into t3 values (9,2,3,4,5,6);
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insert into t4 values (1,2,3,4,5,6);
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insert into t4 values (2,2,3,4,5,6);
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insert into t4 values (3,2,3,4,5,6);
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insert into t4 values (4,2,3,4,5,6);
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insert into t4 values (5,2,3,4,5,6);
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insert into t4 values (6,2,3,4,5,6);
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insert into t4 values (7,2,3,4,5,6);
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insert into t4 values (8,2,3,4,5,6);
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insert into t4 values (9,2,3,4,5,6);
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insert into t4 values (10,2,3,4,5,6);
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insert into t4 values (11,2,3,4,5,6);
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insert into t4 values (12,2,3,4,5,6);
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insert into t5 values (1,2,3,4,5,6);
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insert into t5 values (2,2,3,4,5,6);
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insert into t5 values (3,2,3,4,5,6);
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insert into t5 values (4,2,3,4,5,6);
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insert into t5 values (5,2,3,4,5,6);
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insert into t5 values (6,2,3,4,5,6);
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insert into t5 values (7,2,3,4,5,6);
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insert into t5 values (8,2,3,4,5,6);
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insert into t5 values (9,2,3,4,5,6);
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insert into t5 values (10,2,3,4,5,6);
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insert into t5 values (11,2,3,4,5,6);
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insert into t5 values (12,2,3,4,5,6);
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insert into t5 values (13,2,3,4,5,6);
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insert into t5 values (14,2,3,4,5,6);
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insert into t5 values (15,2,3,4,5,6);
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insert into t6 values (1,2,3,4,5,6);
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insert into t6 values (2,2,3,4,5,6);
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insert into t6 values (3,2,3,4,5,6);
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insert into t6 values (4,2,3,4,5,6);
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insert into t6 values (5,2,3,4,5,6);
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insert into t6 values (6,2,3,4,5,6);
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insert into t6 values (7,2,3,4,5,6);
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insert into t6 values (8,2,3,4,5,6);
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insert into t6 values (9,2,3,4,5,6);
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insert into t6 values (10,2,3,4,5,6);
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insert into t6 values (11,2,3,4,5,6);
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insert into t6 values (12,2,3,4,5,6);
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insert into t6 values (13,2,3,4,5,6);
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insert into t6 values (14,2,3,4,5,6);
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insert into t6 values (15,2,3,4,5,6);
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insert into t6 values (16,2,3,4,5,6);
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insert into t6 values (17,2,3,4,5,6);
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insert into t6 values (18,2,3,4,5,6);
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insert into t7 values (1,2,3,4,5,6);
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insert into t7 values (2,2,3,4,5,6);
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insert into t7 values (3,2,3,4,5,6);
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insert into t7 values (4,2,3,4,5,6);
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insert into t7 values (5,2,3,4,5,6);
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insert into t7 values (6,2,3,4,5,6);
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insert into t7 values (7,2,3,4,5,6);
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insert into t7 values (8,2,3,4,5,6);
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insert into t7 values (9,2,3,4,5,6);
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insert into t7 values (10,2,3,4,5,6);
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insert into t7 values (11,2,3,4,5,6);
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insert into t7 values (12,2,3,4,5,6);
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insert into t7 values (13,2,3,4,5,6);
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insert into t7 values (14,2,3,4,5,6);
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insert into t7 values (15,2,3,4,5,6);
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insert into t7 values (16,2,3,4,5,6);
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insert into t7 values (17,2,3,4,5,6);
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insert into t7 values (18,2,3,4,5,6);
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insert into t7 values (19,2,3,4,5,6);
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insert into t7 values (20,2,3,4,5,6);
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insert into t7 values (21,2,3,4,5,6);
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select @@optimizer_search_depth;
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@@optimizer_search_depth
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62
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select @@optimizer_prune_level;
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@@optimizer_prune_level
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1
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set optimizer_search_depth=63;
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select @@optimizer_search_depth;
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@@optimizer_search_depth
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63
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explain select t1.c11 from t1, t2, t3, t4, t5, t6, t7 where t1.c12 = t2.c21 and t2.c22 = t3.c31 and t3.c32 = t4.c41 and t4.c42 = t5.c51 and t5.c52 = t6.c61 and t6.c62 = t7.c71;
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id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
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1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	3	
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1	SIMPLE	t2	ALL	NULL	NULL	NULL	NULL	6	Using where; Using join buffer
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1	SIMPLE	t3	eq_ref	PRIMARY	PRIMARY	4	test.t2.c22	1	
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1	SIMPLE	t4	ALL	NULL	NULL	NULL	NULL	12	Using where; Using join buffer
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1	SIMPLE	t5	eq_ref	PRIMARY	PRIMARY	4	test.t4.c42	1	
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1	SIMPLE	t6	ALL	NULL	NULL	NULL	NULL	18	Using where; Using join buffer
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1	SIMPLE	t7	eq_ref	PRIMARY	PRIMARY	4	test.t6.c62	1	Using index
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show status like 'Last_query_cost';
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Variable_name	Value
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Last_query_cost	821.837037
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explain select t1.c11 from t7, t6, t5, t4, t3, t2, t1 where t1.c12 = t2.c21 and t2.c22 = t3.c31 and t3.c32 = t4.c41 and t4.c42 = t5.c51 and t5.c52 = t6.c61 and t6.c62 = t7.c71;
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id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
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1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	3	
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1	SIMPLE	t2	ALL	NULL	NULL	NULL	NULL	6	Using where; Using join buffer
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1	SIMPLE	t3	eq_ref	PRIMARY	PRIMARY	4	test.t2.c22	1	
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1	SIMPLE	t4	ALL	NULL	NULL	NULL	NULL	12	Using where; Using join buffer
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1	SIMPLE	t5	eq_ref	PRIMARY	PRIMARY	4	test.t4.c42	1	
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1	SIMPLE	t6	ALL	NULL	NULL	NULL	NULL	18	Using where; Using join buffer
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1	SIMPLE	t7	eq_ref	PRIMARY	PRIMARY	4	test.t6.c62	1	Using index
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show status like 'Last_query_cost';
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Variable_name	Value
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Last_query_cost	821.837037
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explain select t1.c11 from t1, t2, t3, t4, t5, t6, t7 where t1.c11 = t2.c21 and t1.c12 = t3.c31 and t1.c13 = t4.c41 and t1.c14 = t5.c51 and t1.c15 = t6.c61 and t1.c16 = t7.c71;
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id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
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1	SIMPLE	t1	ALL	PRIMARY	NULL	NULL	NULL	3	
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1	SIMPLE	t2	ALL	NULL	NULL	NULL	NULL	6	Using where; Using join buffer
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1	SIMPLE	t3	eq_ref	PRIMARY	PRIMARY	4	test.t1.c12	1	Using index
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1	SIMPLE	t4	ALL	NULL	NULL	NULL	NULL	12	Using where; Using join buffer
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1	SIMPLE	t5	eq_ref	PRIMARY	PRIMARY	4	test.t1.c14	1	Using index
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1	SIMPLE	t6	ALL	NULL	NULL	NULL	NULL	18	Using where; Using join buffer
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1	SIMPLE	t7	eq_ref	PRIMARY	PRIMARY	4	test.t1.c16	1	Using index
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show status like 'Last_query_cost';
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Variable_name	Value
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Last_query_cost	794.837037
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explain select t1.c11 from t7, t6, t5, t4, t3, t2, t1 where t1.c11 = t2.c21 and t1.c12 = t3.c31 and t1.c13 = t4.c41 and t1.c14 = t5.c51 and t1.c15 = t6.c61 and t1.c16 = t7.c71;
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id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
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1	SIMPLE	t1	ALL	PRIMARY	NULL	NULL	NULL	3	
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1	SIMPLE	t2	ALL	NULL	NULL	NULL	NULL	6	Using where; Using join buffer
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1	SIMPLE	t3	eq_ref	PRIMARY	PRIMARY	4	test.t1.c12	1	Using index
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1	SIMPLE	t4	ALL	NULL	NULL	NULL	NULL	12	Using where; Using join buffer
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1	SIMPLE	t5	eq_ref	PRIMARY	PRIMARY	4	test.t1.c14	1	Using index
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1	SIMPLE	t6	ALL	NULL	NULL	NULL	NULL	18	Using where; Using join buffer
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1	SIMPLE	t7	eq_ref	PRIMARY	PRIMARY	4	test.t1.c16	1	Using index
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show status like 'Last_query_cost';
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Variable_name	Value
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Last_query_cost	794.837037
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explain select t1.c11 from t1, t2, t3, t4, t5, t6, t7 where t1.c11 = t2.c21 and t1.c12 = t3.c31 and t1.c13 = t4.c41 and t1.c14 = t5.c51 and t1.c15 = t6.c61 and t1.c16 = t7.c71 and t2.c22 = t3.c32 and t2.c23 = t4.c42 and t2.c24 = t5.c52 and t2.c25 = t6.c62 and t2.c26 = t7.c72 and t3.c33 = t4.c43 and t3.c34 = t5.c53 and t3.c35 = t6.c63 and t3.c36 = t7.c73 and t4.c42 = t5.c54 and t4.c43 = t6.c64 and t4.c44 = t7.c74 and t5.c52 = t6.c65 and t5.c53 = t7.c75 and t6.c62 = t7.c76;
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id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
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1	SIMPLE	t1	ALL	PRIMARY	NULL	NULL	NULL	3	
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1	SIMPLE	t2	ALL	NULL	NULL	NULL	NULL	6	Using where; Using join buffer
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1	SIMPLE	t3	eq_ref	PRIMARY	PRIMARY	4	test.t1.c12	1	Using where
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1	SIMPLE	t4	ALL	NULL	NULL	NULL	NULL	12	Using where; Using join buffer
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1	SIMPLE	t5	eq_ref	PRIMARY	PRIMARY	4	test.t1.c14	1	Using where
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1	SIMPLE	t6	ALL	NULL	NULL	NULL	NULL	18	Using where; Using join buffer
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1	SIMPLE	t7	eq_ref	PRIMARY	PRIMARY	4	test.t1.c16	1	Using where
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show status like 'Last_query_cost';
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Variable_name	Value
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Last_query_cost	794.837037
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explain select t1.c11 from t7, t6, t5, t4, t3, t2, t1 where t1.c11 = t2.c21 and t1.c12 = t3.c31 and t1.c13 = t4.c41 and t1.c14 = t5.c51 and t1.c15 = t6.c61 and t1.c16 = t7.c71 and t2.c22 = t3.c32 and t2.c23 = t4.c42 and t2.c24 = t5.c52 and t2.c25 = t6.c62 and t2.c26 = t7.c72 and t3.c33 = t4.c43 and t3.c34 = t5.c53 and t3.c35 = t6.c63 and t3.c36 = t7.c73 and t4.c42 = t5.c54 and t4.c43 = t6.c64 and t4.c44 = t7.c74 and t5.c52 = t6.c65 and t5.c53 = t7.c75 and t6.c62 = t7.c76;
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id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
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1	SIMPLE	t1	ALL	PRIMARY	NULL	NULL	NULL	3	
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1	SIMPLE	t2	ALL	NULL	NULL	NULL	NULL	6	Using where; Using join buffer
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1	SIMPLE	t3	eq_ref	PRIMARY	PRIMARY	4	test.t1.c12	1	Using where
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1	SIMPLE	t4	ALL	NULL	NULL	NULL	NULL	12	Using where; Using join buffer
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1	SIMPLE	t5	eq_ref	PRIMARY	PRIMARY	4	test.t1.c14	1	Using where
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1	SIMPLE	t6	ALL	NULL	NULL	NULL	NULL	18	Using where; Using join buffer
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1	SIMPLE	t7	eq_ref	PRIMARY	PRIMARY	4	test.t1.c16	1	Using where
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show status like 'Last_query_cost';
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Variable_name	Value
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Last_query_cost	794.837037
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set optimizer_prune_level=0;
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select @@optimizer_prune_level;
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@@optimizer_prune_level
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0
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set optimizer_search_depth=0;
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select @@optimizer_search_depth;
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@@optimizer_search_depth
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0
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explain select t1.c11 from t1, t2, t3, t4, t5, t6, t7 where t1.c12 = t2.c21 and t2.c22 = t3.c31 and t3.c32 = t4.c41 and t4.c42 = t5.c51 and t5.c52 = t6.c61 and t6.c62 = t7.c71;
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id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
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1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	3	
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1	SIMPLE	t2	ALL	NULL	NULL	NULL	NULL	6	Using where; Using join buffer
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1	SIMPLE	t3	eq_ref	PRIMARY	PRIMARY	4	test.t2.c22	1	
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1	SIMPLE	t4	ALL	NULL	NULL	NULL	NULL	12	Using where; Using join buffer
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1	SIMPLE	t5	eq_ref	PRIMARY	PRIMARY	4	test.t4.c42	1	
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1	SIMPLE	t6	ALL	NULL	NULL	NULL	NULL	18	Using where; Using join buffer
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1	SIMPLE	t7	eq_ref	PRIMARY	PRIMARY	4	test.t6.c62	1	Using index
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show status like 'Last_query_cost';
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Variable_name	Value
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Last_query_cost	821.837037
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explain select t1.c11 from t7, t6, t5, t4, t3, t2, t1 where t1.c12 = t2.c21 and t2.c22 = t3.c31 and t3.c32 = t4.c41 and t4.c42 = t5.c51 and t5.c52 = t6.c61 and t6.c62 = t7.c71;
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id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
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1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	3	
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1	SIMPLE	t2	ALL	NULL	NULL	NULL	NULL	6	Using where; Using join buffer
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1	SIMPLE	t3	eq_ref	PRIMARY	PRIMARY	4	test.t2.c22	1	
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1	SIMPLE	t4	ALL	NULL	NULL	NULL	NULL	12	Using where; Using join buffer
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1	SIMPLE	t5	eq_ref	PRIMARY	PRIMARY	4	test.t4.c42	1	
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1	SIMPLE	t6	ALL	NULL	NULL	NULL	NULL	18	Using where; Using join buffer
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1	SIMPLE	t7	eq_ref	PRIMARY	PRIMARY	4	test.t6.c62	1	Using index
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show status like 'Last_query_cost';
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Variable_name	Value
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Last_query_cost	821.837037
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explain select t1.c11 from t1, t2, t3, t4, t5, t6, t7 where t1.c11 = t2.c21 and t1.c12 = t3.c31 and t1.c13 = t4.c41 and t1.c14 = t5.c51 and t1.c15 = t6.c61 and t1.c16 = t7.c71;
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id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
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1	SIMPLE	t2	ALL	NULL	NULL	NULL	NULL	6	
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1	SIMPLE	t4	ALL	NULL	NULL	NULL	NULL	12	Using join buffer
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1	SIMPLE	t1	eq_ref	PRIMARY	PRIMARY	4	test.t2.c21	1	Using where
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1	SIMPLE	t3	eq_ref	PRIMARY	PRIMARY	4	test.t1.c12	1	Using index
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1	SIMPLE	t5	eq_ref	PRIMARY	PRIMARY	4	test.t1.c14	1	Using index
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1	SIMPLE	t6	ALL	NULL	NULL	NULL	NULL	18	Using where; Using join buffer
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1	SIMPLE	t7	eq_ref	PRIMARY	PRIMARY	4	test.t1.c16	1	Using index
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show status like 'Last_query_cost';
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Variable_name	Value
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Last_query_cost	289.418727
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explain select t1.c11 from t7, t6, t5, t4, t3, t2, t1 where t1.c11 = t2.c21 and t1.c12 = t3.c31 and t1.c13 = t4.c41 and t1.c14 = t5.c51 and t1.c15 = t6.c61 and t1.c16 = t7.c71;
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id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
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1	SIMPLE	t2	ALL	NULL	NULL	NULL	NULL	6	
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1	SIMPLE	t4	ALL	NULL	NULL	NULL	NULL	12	Using join buffer
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1	SIMPLE	t1	eq_ref	PRIMARY	PRIMARY	4	test.t2.c21	1	Using where
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1	SIMPLE	t3	eq_ref	PRIMARY	PRIMARY	4	test.t1.c12	1	Using index
 | 
						|
1	SIMPLE	t5	eq_ref	PRIMARY	PRIMARY	4	test.t1.c14	1	Using index
 | 
						|
1	SIMPLE	t6	ALL	NULL	NULL	NULL	NULL	18	Using where; Using join buffer
 | 
						|
1	SIMPLE	t7	eq_ref	PRIMARY	PRIMARY	4	test.t1.c16	1	Using index
 | 
						|
show status like 'Last_query_cost';
 | 
						|
Variable_name	Value
 | 
						|
Last_query_cost	289.418727
 | 
						|
explain select t1.c11 from t1, t2, t3, t4, t5, t6, t7 where t1.c11 = t2.c21 and t1.c12 = t3.c31 and t1.c13 = t4.c41 and t1.c14 = t5.c51 and t1.c15 = t6.c61 and t1.c16 = t7.c71 and t2.c22 = t3.c32 and t2.c23 = t4.c42 and t2.c24 = t5.c52 and t2.c25 = t6.c62 and t2.c26 = t7.c72 and t3.c33 = t4.c43 and t3.c34 = t5.c53 and t3.c35 = t6.c63 and t3.c36 = t7.c73 and t4.c42 = t5.c54 and t4.c43 = t6.c64 and t4.c44 = t7.c74 and t5.c52 = t6.c65 and t5.c53 = t7.c75 and t6.c62 = t7.c76;
 | 
						|
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 | 
						|
1	SIMPLE	t2	ALL	NULL	NULL	NULL	NULL	6	
 | 
						|
1	SIMPLE	t4	ALL	NULL	NULL	NULL	NULL	12	Using where; Using join buffer
 | 
						|
1	SIMPLE	t1	eq_ref	PRIMARY	PRIMARY	4	test.t2.c21	1	Using where
 | 
						|
1	SIMPLE	t3	eq_ref	PRIMARY	PRIMARY	4	test.t1.c12	1	Using where
 | 
						|
1	SIMPLE	t5	eq_ref	PRIMARY	PRIMARY	4	test.t1.c14	1	Using where
 | 
						|
1	SIMPLE	t6	ALL	NULL	NULL	NULL	NULL	18	Using where; Using join buffer
 | 
						|
1	SIMPLE	t7	eq_ref	PRIMARY	PRIMARY	4	test.t1.c16	1	Using where
 | 
						|
show status like 'Last_query_cost';
 | 
						|
Variable_name	Value
 | 
						|
Last_query_cost	289.418727
 | 
						|
explain select t1.c11 from t7, t6, t5, t4, t3, t2, t1 where t1.c11 = t2.c21 and t1.c12 = t3.c31 and t1.c13 = t4.c41 and t1.c14 = t5.c51 and t1.c15 = t6.c61 and t1.c16 = t7.c71 and t2.c22 = t3.c32 and t2.c23 = t4.c42 and t2.c24 = t5.c52 and t2.c25 = t6.c62 and t2.c26 = t7.c72 and t3.c33 = t4.c43 and t3.c34 = t5.c53 and t3.c35 = t6.c63 and t3.c36 = t7.c73 and t4.c42 = t5.c54 and t4.c43 = t6.c64 and t4.c44 = t7.c74 and t5.c52 = t6.c65 and t5.c53 = t7.c75 and t6.c62 = t7.c76;
 | 
						|
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 | 
						|
1	SIMPLE	t2	ALL	NULL	NULL	NULL	NULL	6	
 | 
						|
1	SIMPLE	t4	ALL	NULL	NULL	NULL	NULL	12	Using where; Using join buffer
 | 
						|
1	SIMPLE	t1	eq_ref	PRIMARY	PRIMARY	4	test.t2.c21	1	Using where
 | 
						|
1	SIMPLE	t3	eq_ref	PRIMARY	PRIMARY	4	test.t1.c12	1	Using where
 | 
						|
1	SIMPLE	t5	eq_ref	PRIMARY	PRIMARY	4	test.t1.c14	1	Using where
 | 
						|
1	SIMPLE	t6	ALL	NULL	NULL	NULL	NULL	18	Using where; Using join buffer
 | 
						|
1	SIMPLE	t7	eq_ref	PRIMARY	PRIMARY	4	test.t1.c16	1	Using where
 | 
						|
show status like 'Last_query_cost';
 | 
						|
Variable_name	Value
 | 
						|
Last_query_cost	289.418727
 | 
						|
set optimizer_search_depth=1;
 | 
						|
select @@optimizer_search_depth;
 | 
						|
@@optimizer_search_depth
 | 
						|
1
 | 
						|
explain select t1.c11 from t1, t2, t3, t4, t5, t6, t7 where t1.c12 = t2.c21 and t2.c22 = t3.c31 and t3.c32 = t4.c41 and t4.c42 = t5.c51 and t5.c52 = t6.c61 and t6.c62 = t7.c71;
 | 
						|
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 | 
						|
1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	3	
 | 
						|
1	SIMPLE	t2	ALL	NULL	NULL	NULL	NULL	6	Using where; Using join buffer
 | 
						|
1	SIMPLE	t3	eq_ref	PRIMARY	PRIMARY	4	test.t2.c22	1	
 | 
						|
1	SIMPLE	t4	ALL	NULL	NULL	NULL	NULL	12	Using where; Using join buffer
 | 
						|
1	SIMPLE	t5	eq_ref	PRIMARY	PRIMARY	4	test.t4.c42	1	
 | 
						|
1	SIMPLE	t6	ALL	NULL	NULL	NULL	NULL	18	Using where; Using join buffer
 | 
						|
1	SIMPLE	t7	eq_ref	PRIMARY	PRIMARY	4	test.t6.c62	1	Using index
 | 
						|
show status like 'Last_query_cost';
 | 
						|
Variable_name	Value
 | 
						|
Last_query_cost	821.837037
 | 
						|
explain select t1.c11 from t7, t6, t5, t4, t3, t2, t1 where t1.c12 = t2.c21 and t2.c22 = t3.c31 and t3.c32 = t4.c41 and t4.c42 = t5.c51 and t5.c52 = t6.c61 and t6.c62 = t7.c71;
 | 
						|
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 | 
						|
1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	3	
 | 
						|
1	SIMPLE	t2	ALL	NULL	NULL	NULL	NULL	6	Using where; Using join buffer
 | 
						|
1	SIMPLE	t3	eq_ref	PRIMARY	PRIMARY	4	test.t2.c22	1	
 | 
						|
1	SIMPLE	t4	ALL	NULL	NULL	NULL	NULL	12	Using where; Using join buffer
 | 
						|
1	SIMPLE	t5	eq_ref	PRIMARY	PRIMARY	4	test.t4.c42	1	
 | 
						|
1	SIMPLE	t6	ALL	NULL	NULL	NULL	NULL	18	Using where; Using join buffer
 | 
						|
1	SIMPLE	t7	eq_ref	PRIMARY	PRIMARY	4	test.t6.c62	1	Using index
 | 
						|
show status like 'Last_query_cost';
 | 
						|
Variable_name	Value
 | 
						|
Last_query_cost	821.837037
 | 
						|
explain select t1.c11 from t1, t2, t3, t4, t5, t6, t7 where t1.c11 = t2.c21 and t1.c12 = t3.c31 and t1.c13 = t4.c41 and t1.c14 = t5.c51 and t1.c15 = t6.c61 and t1.c16 = t7.c71;
 | 
						|
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 | 
						|
1	SIMPLE	t1	ALL	PRIMARY	NULL	NULL	NULL	3	
 | 
						|
1	SIMPLE	t3	eq_ref	PRIMARY	PRIMARY	4	test.t1.c12	1	Using index
 | 
						|
1	SIMPLE	t5	eq_ref	PRIMARY	PRIMARY	4	test.t1.c14	1	Using index
 | 
						|
1	SIMPLE	t7	eq_ref	PRIMARY	PRIMARY	4	test.t1.c16	1	Using index
 | 
						|
1	SIMPLE	t2	ALL	NULL	NULL	NULL	NULL	6	Using where; Using join buffer
 | 
						|
1	SIMPLE	t4	ALL	NULL	NULL	NULL	NULL	12	Using where; Using join buffer
 | 
						|
1	SIMPLE	t6	ALL	NULL	NULL	NULL	NULL	18	Using where; Using join buffer
 | 
						|
show status like 'Last_query_cost';
 | 
						|
Variable_name	Value
 | 
						|
Last_query_cost	794.837037
 | 
						|
explain select t1.c11 from t7, t6, t5, t4, t3, t2, t1 where t1.c11 = t2.c21 and t1.c12 = t3.c31 and t1.c13 = t4.c41 and t1.c14 = t5.c51 and t1.c15 = t6.c61 and t1.c16 = t7.c71;
 | 
						|
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 | 
						|
1	SIMPLE	t1	ALL	PRIMARY	NULL	NULL	NULL	3	
 | 
						|
1	SIMPLE	t3	eq_ref	PRIMARY	PRIMARY	4	test.t1.c12	1	Using index
 | 
						|
1	SIMPLE	t5	eq_ref	PRIMARY	PRIMARY	4	test.t1.c14	1	Using index
 | 
						|
1	SIMPLE	t7	eq_ref	PRIMARY	PRIMARY	4	test.t1.c16	1	Using index
 | 
						|
1	SIMPLE	t2	ALL	NULL	NULL	NULL	NULL	6	Using where; Using join buffer
 | 
						|
1	SIMPLE	t4	ALL	NULL	NULL	NULL	NULL	12	Using where; Using join buffer
 | 
						|
1	SIMPLE	t6	ALL	NULL	NULL	NULL	NULL	18	Using where; Using join buffer
 | 
						|
show status like 'Last_query_cost';
 | 
						|
Variable_name	Value
 | 
						|
Last_query_cost	794.837037
 | 
						|
explain select t1.c11 from t1, t2, t3, t4, t5, t6, t7 where t1.c11 = t2.c21 and t1.c12 = t3.c31 and t1.c13 = t4.c41 and t1.c14 = t5.c51 and t1.c15 = t6.c61 and t1.c16 = t7.c71 and t2.c22 = t3.c32 and t2.c23 = t4.c42 and t2.c24 = t5.c52 and t2.c25 = t6.c62 and t2.c26 = t7.c72 and t3.c33 = t4.c43 and t3.c34 = t5.c53 and t3.c35 = t6.c63 and t3.c36 = t7.c73 and t4.c42 = t5.c54 and t4.c43 = t6.c64 and t4.c44 = t7.c74 and t5.c52 = t6.c65 and t5.c53 = t7.c75 and t6.c62 = t7.c76;
 | 
						|
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 | 
						|
1	SIMPLE	t1	ALL	PRIMARY	NULL	NULL	NULL	3	
 | 
						|
1	SIMPLE	t3	eq_ref	PRIMARY	PRIMARY	4	test.t1.c12	1	
 | 
						|
1	SIMPLE	t5	eq_ref	PRIMARY	PRIMARY	4	test.t1.c14	1	Using where
 | 
						|
1	SIMPLE	t7	eq_ref	PRIMARY	PRIMARY	4	test.t1.c16	1	Using where
 | 
						|
1	SIMPLE	t2	ALL	NULL	NULL	NULL	NULL	6	Using where; Using join buffer
 | 
						|
1	SIMPLE	t4	ALL	NULL	NULL	NULL	NULL	12	Using where; Using join buffer
 | 
						|
1	SIMPLE	t6	ALL	NULL	NULL	NULL	NULL	18	Using where; Using join buffer
 | 
						|
show status like 'Last_query_cost';
 | 
						|
Variable_name	Value
 | 
						|
Last_query_cost	794.837037
 | 
						|
explain select t1.c11 from t7, t6, t5, t4, t3, t2, t1 where t1.c11 = t2.c21 and t1.c12 = t3.c31 and t1.c13 = t4.c41 and t1.c14 = t5.c51 and t1.c15 = t6.c61 and t1.c16 = t7.c71 and t2.c22 = t3.c32 and t2.c23 = t4.c42 and t2.c24 = t5.c52 and t2.c25 = t6.c62 and t2.c26 = t7.c72 and t3.c33 = t4.c43 and t3.c34 = t5.c53 and t3.c35 = t6.c63 and t3.c36 = t7.c73 and t4.c42 = t5.c54 and t4.c43 = t6.c64 and t4.c44 = t7.c74 and t5.c52 = t6.c65 and t5.c53 = t7.c75 and t6.c62 = t7.c76;
 | 
						|
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 | 
						|
1	SIMPLE	t1	ALL	PRIMARY	NULL	NULL	NULL	3	
 | 
						|
1	SIMPLE	t3	eq_ref	PRIMARY	PRIMARY	4	test.t1.c12	1	
 | 
						|
1	SIMPLE	t5	eq_ref	PRIMARY	PRIMARY	4	test.t1.c14	1	Using where
 | 
						|
1	SIMPLE	t7	eq_ref	PRIMARY	PRIMARY	4	test.t1.c16	1	Using where
 | 
						|
1	SIMPLE	t2	ALL	NULL	NULL	NULL	NULL	6	Using where; Using join buffer
 | 
						|
1	SIMPLE	t4	ALL	NULL	NULL	NULL	NULL	12	Using where; Using join buffer
 | 
						|
1	SIMPLE	t6	ALL	NULL	NULL	NULL	NULL	18	Using where; Using join buffer
 | 
						|
show status like 'Last_query_cost';
 | 
						|
Variable_name	Value
 | 
						|
Last_query_cost	794.837037
 | 
						|
set optimizer_search_depth=62;
 | 
						|
select @@optimizer_search_depth;
 | 
						|
@@optimizer_search_depth
 | 
						|
62
 | 
						|
explain select t1.c11 from t1, t2, t3, t4, t5, t6, t7 where t1.c12 = t2.c21 and t2.c22 = t3.c31 and t3.c32 = t4.c41 and t4.c42 = t5.c51 and t5.c52 = t6.c61 and t6.c62 = t7.c71;
 | 
						|
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 | 
						|
1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	3	
 | 
						|
1	SIMPLE	t2	ALL	NULL	NULL	NULL	NULL	6	Using where; Using join buffer
 | 
						|
1	SIMPLE	t3	eq_ref	PRIMARY	PRIMARY	4	test.t2.c22	1	
 | 
						|
1	SIMPLE	t4	ALL	NULL	NULL	NULL	NULL	12	Using where; Using join buffer
 | 
						|
1	SIMPLE	t5	eq_ref	PRIMARY	PRIMARY	4	test.t4.c42	1	
 | 
						|
1	SIMPLE	t6	ALL	NULL	NULL	NULL	NULL	18	Using where; Using join buffer
 | 
						|
1	SIMPLE	t7	eq_ref	PRIMARY	PRIMARY	4	test.t6.c62	1	Using index
 | 
						|
show status like 'Last_query_cost';
 | 
						|
Variable_name	Value
 | 
						|
Last_query_cost	821.837037
 | 
						|
explain select t1.c11 from t7, t6, t5, t4, t3, t2, t1 where t1.c12 = t2.c21 and t2.c22 = t3.c31 and t3.c32 = t4.c41 and t4.c42 = t5.c51 and t5.c52 = t6.c61 and t6.c62 = t7.c71;
 | 
						|
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 | 
						|
1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	3	
 | 
						|
1	SIMPLE	t2	ALL	NULL	NULL	NULL	NULL	6	Using where; Using join buffer
 | 
						|
1	SIMPLE	t3	eq_ref	PRIMARY	PRIMARY	4	test.t2.c22	1	
 | 
						|
1	SIMPLE	t4	ALL	NULL	NULL	NULL	NULL	12	Using where; Using join buffer
 | 
						|
1	SIMPLE	t5	eq_ref	PRIMARY	PRIMARY	4	test.t4.c42	1	
 | 
						|
1	SIMPLE	t6	ALL	NULL	NULL	NULL	NULL	18	Using where; Using join buffer
 | 
						|
1	SIMPLE	t7	eq_ref	PRIMARY	PRIMARY	4	test.t6.c62	1	Using index
 | 
						|
show status like 'Last_query_cost';
 | 
						|
Variable_name	Value
 | 
						|
Last_query_cost	821.837037
 | 
						|
explain select t1.c11 from t1, t2, t3, t4, t5, t6, t7 where t1.c11 = t2.c21 and t1.c12 = t3.c31 and t1.c13 = t4.c41 and t1.c14 = t5.c51 and t1.c15 = t6.c61 and t1.c16 = t7.c71;
 | 
						|
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 | 
						|
1	SIMPLE	t2	ALL	NULL	NULL	NULL	NULL	6	
 | 
						|
1	SIMPLE	t4	ALL	NULL	NULL	NULL	NULL	12	Using join buffer
 | 
						|
1	SIMPLE	t1	eq_ref	PRIMARY	PRIMARY	4	test.t2.c21	1	Using where
 | 
						|
1	SIMPLE	t3	eq_ref	PRIMARY	PRIMARY	4	test.t1.c12	1	Using index
 | 
						|
1	SIMPLE	t5	eq_ref	PRIMARY	PRIMARY	4	test.t1.c14	1	Using index
 | 
						|
1	SIMPLE	t6	ALL	NULL	NULL	NULL	NULL	18	Using where; Using join buffer
 | 
						|
1	SIMPLE	t7	eq_ref	PRIMARY	PRIMARY	4	test.t1.c16	1	Using index
 | 
						|
show status like 'Last_query_cost';
 | 
						|
Variable_name	Value
 | 
						|
Last_query_cost	289.418727
 | 
						|
explain select t1.c11 from t7, t6, t5, t4, t3, t2, t1 where t1.c11 = t2.c21 and t1.c12 = t3.c31 and t1.c13 = t4.c41 and t1.c14 = t5.c51 and t1.c15 = t6.c61 and t1.c16 = t7.c71;
 | 
						|
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 | 
						|
1	SIMPLE	t2	ALL	NULL	NULL	NULL	NULL	6	
 | 
						|
1	SIMPLE	t4	ALL	NULL	NULL	NULL	NULL	12	Using join buffer
 | 
						|
1	SIMPLE	t1	eq_ref	PRIMARY	PRIMARY	4	test.t2.c21	1	Using where
 | 
						|
1	SIMPLE	t3	eq_ref	PRIMARY	PRIMARY	4	test.t1.c12	1	Using index
 | 
						|
1	SIMPLE	t5	eq_ref	PRIMARY	PRIMARY	4	test.t1.c14	1	Using index
 | 
						|
1	SIMPLE	t6	ALL	NULL	NULL	NULL	NULL	18	Using where; Using join buffer
 | 
						|
1	SIMPLE	t7	eq_ref	PRIMARY	PRIMARY	4	test.t1.c16	1	Using index
 | 
						|
show status like 'Last_query_cost';
 | 
						|
Variable_name	Value
 | 
						|
Last_query_cost	289.418727
 | 
						|
explain select t1.c11 from t1, t2, t3, t4, t5, t6, t7 where t1.c11 = t2.c21 and t1.c12 = t3.c31 and t1.c13 = t4.c41 and t1.c14 = t5.c51 and t1.c15 = t6.c61 and t1.c16 = t7.c71 and t2.c22 = t3.c32 and t2.c23 = t4.c42 and t2.c24 = t5.c52 and t2.c25 = t6.c62 and t2.c26 = t7.c72 and t3.c33 = t4.c43 and t3.c34 = t5.c53 and t3.c35 = t6.c63 and t3.c36 = t7.c73 and t4.c42 = t5.c54 and t4.c43 = t6.c64 and t4.c44 = t7.c74 and t5.c52 = t6.c65 and t5.c53 = t7.c75 and t6.c62 = t7.c76;
 | 
						|
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 | 
						|
1	SIMPLE	t2	ALL	NULL	NULL	NULL	NULL	6	
 | 
						|
1	SIMPLE	t4	ALL	NULL	NULL	NULL	NULL	12	Using where; Using join buffer
 | 
						|
1	SIMPLE	t1	eq_ref	PRIMARY	PRIMARY	4	test.t2.c21	1	Using where
 | 
						|
1	SIMPLE	t3	eq_ref	PRIMARY	PRIMARY	4	test.t1.c12	1	Using where
 | 
						|
1	SIMPLE	t5	eq_ref	PRIMARY	PRIMARY	4	test.t1.c14	1	Using where
 | 
						|
1	SIMPLE	t6	ALL	NULL	NULL	NULL	NULL	18	Using where; Using join buffer
 | 
						|
1	SIMPLE	t7	eq_ref	PRIMARY	PRIMARY	4	test.t1.c16	1	Using where
 | 
						|
show status like 'Last_query_cost';
 | 
						|
Variable_name	Value
 | 
						|
Last_query_cost	289.418727
 | 
						|
explain select t1.c11 from t7, t6, t5, t4, t3, t2, t1 where t1.c11 = t2.c21 and t1.c12 = t3.c31 and t1.c13 = t4.c41 and t1.c14 = t5.c51 and t1.c15 = t6.c61 and t1.c16 = t7.c71 and t2.c22 = t3.c32 and t2.c23 = t4.c42 and t2.c24 = t5.c52 and t2.c25 = t6.c62 and t2.c26 = t7.c72 and t3.c33 = t4.c43 and t3.c34 = t5.c53 and t3.c35 = t6.c63 and t3.c36 = t7.c73 and t4.c42 = t5.c54 and t4.c43 = t6.c64 and t4.c44 = t7.c74 and t5.c52 = t6.c65 and t5.c53 = t7.c75 and t6.c62 = t7.c76;
 | 
						|
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 | 
						|
1	SIMPLE	t2	ALL	NULL	NULL	NULL	NULL	6	
 | 
						|
1	SIMPLE	t4	ALL	NULL	NULL	NULL	NULL	12	Using where; Using join buffer
 | 
						|
1	SIMPLE	t1	eq_ref	PRIMARY	PRIMARY	4	test.t2.c21	1	Using where
 | 
						|
1	SIMPLE	t3	eq_ref	PRIMARY	PRIMARY	4	test.t1.c12	1	Using where
 | 
						|
1	SIMPLE	t5	eq_ref	PRIMARY	PRIMARY	4	test.t1.c14	1	Using where
 | 
						|
1	SIMPLE	t6	ALL	NULL	NULL	NULL	NULL	18	Using where; Using join buffer
 | 
						|
1	SIMPLE	t7	eq_ref	PRIMARY	PRIMARY	4	test.t1.c16	1	Using where
 | 
						|
show status like 'Last_query_cost';
 | 
						|
Variable_name	Value
 | 
						|
Last_query_cost	289.418727
 | 
						|
set optimizer_prune_level=1;
 | 
						|
select @@optimizer_prune_level;
 | 
						|
@@optimizer_prune_level
 | 
						|
1
 | 
						|
set optimizer_search_depth=0;
 | 
						|
select @@optimizer_search_depth;
 | 
						|
@@optimizer_search_depth
 | 
						|
0
 | 
						|
explain select t1.c11 from t1, t2, t3, t4, t5, t6, t7 where t1.c12 = t2.c21 and t2.c22 = t3.c31 and t3.c32 = t4.c41 and t4.c42 = t5.c51 and t5.c52 = t6.c61 and t6.c62 = t7.c71;
 | 
						|
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 | 
						|
1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	3	
 | 
						|
1	SIMPLE	t2	ALL	NULL	NULL	NULL	NULL	6	Using where; Using join buffer
 | 
						|
1	SIMPLE	t3	eq_ref	PRIMARY	PRIMARY	4	test.t2.c22	1	
 | 
						|
1	SIMPLE	t4	ALL	NULL	NULL	NULL	NULL	12	Using where; Using join buffer
 | 
						|
1	SIMPLE	t5	eq_ref	PRIMARY	PRIMARY	4	test.t4.c42	1	
 | 
						|
1	SIMPLE	t6	ALL	NULL	NULL	NULL	NULL	18	Using where; Using join buffer
 | 
						|
1	SIMPLE	t7	eq_ref	PRIMARY	PRIMARY	4	test.t6.c62	1	Using index
 | 
						|
show status like 'Last_query_cost';
 | 
						|
Variable_name	Value
 | 
						|
Last_query_cost	821.837037
 | 
						|
explain select t1.c11 from t7, t6, t5, t4, t3, t2, t1 where t1.c12 = t2.c21 and t2.c22 = t3.c31 and t3.c32 = t4.c41 and t4.c42 = t5.c51 and t5.c52 = t6.c61 and t6.c62 = t7.c71;
 | 
						|
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 | 
						|
1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	3	
 | 
						|
1	SIMPLE	t2	ALL	NULL	NULL	NULL	NULL	6	Using where; Using join buffer
 | 
						|
1	SIMPLE	t3	eq_ref	PRIMARY	PRIMARY	4	test.t2.c22	1	
 | 
						|
1	SIMPLE	t4	ALL	NULL	NULL	NULL	NULL	12	Using where; Using join buffer
 | 
						|
1	SIMPLE	t5	eq_ref	PRIMARY	PRIMARY	4	test.t4.c42	1	
 | 
						|
1	SIMPLE	t6	ALL	NULL	NULL	NULL	NULL	18	Using where; Using join buffer
 | 
						|
1	SIMPLE	t7	eq_ref	PRIMARY	PRIMARY	4	test.t6.c62	1	Using index
 | 
						|
show status like 'Last_query_cost';
 | 
						|
Variable_name	Value
 | 
						|
Last_query_cost	821.837037
 | 
						|
explain select t1.c11 from t1, t2, t3, t4, t5, t6, t7 where t1.c11 = t2.c21 and t1.c12 = t3.c31 and t1.c13 = t4.c41 and t1.c14 = t5.c51 and t1.c15 = t6.c61 and t1.c16 = t7.c71;
 | 
						|
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 | 
						|
1	SIMPLE	t1	ALL	PRIMARY	NULL	NULL	NULL	3	
 | 
						|
1	SIMPLE	t2	ALL	NULL	NULL	NULL	NULL	6	Using where; Using join buffer
 | 
						|
1	SIMPLE	t3	eq_ref	PRIMARY	PRIMARY	4	test.t1.c12	1	Using index
 | 
						|
1	SIMPLE	t4	ALL	NULL	NULL	NULL	NULL	12	Using where; Using join buffer
 | 
						|
1	SIMPLE	t5	eq_ref	PRIMARY	PRIMARY	4	test.t1.c14	1	Using index
 | 
						|
1	SIMPLE	t6	ALL	NULL	NULL	NULL	NULL	18	Using where; Using join buffer
 | 
						|
1	SIMPLE	t7	eq_ref	PRIMARY	PRIMARY	4	test.t1.c16	1	Using index
 | 
						|
show status like 'Last_query_cost';
 | 
						|
Variable_name	Value
 | 
						|
Last_query_cost	794.837037
 | 
						|
explain select t1.c11 from t7, t6, t5, t4, t3, t2, t1 where t1.c11 = t2.c21 and t1.c12 = t3.c31 and t1.c13 = t4.c41 and t1.c14 = t5.c51 and t1.c15 = t6.c61 and t1.c16 = t7.c71;
 | 
						|
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 | 
						|
1	SIMPLE	t1	ALL	PRIMARY	NULL	NULL	NULL	3	
 | 
						|
1	SIMPLE	t2	ALL	NULL	NULL	NULL	NULL	6	Using where; Using join buffer
 | 
						|
1	SIMPLE	t3	eq_ref	PRIMARY	PRIMARY	4	test.t1.c12	1	Using index
 | 
						|
1	SIMPLE	t4	ALL	NULL	NULL	NULL	NULL	12	Using where; Using join buffer
 | 
						|
1	SIMPLE	t5	eq_ref	PRIMARY	PRIMARY	4	test.t1.c14	1	Using index
 | 
						|
1	SIMPLE	t6	ALL	NULL	NULL	NULL	NULL	18	Using where; Using join buffer
 | 
						|
1	SIMPLE	t7	eq_ref	PRIMARY	PRIMARY	4	test.t1.c16	1	Using index
 | 
						|
show status like 'Last_query_cost';
 | 
						|
Variable_name	Value
 | 
						|
Last_query_cost	794.837037
 | 
						|
explain select t1.c11 from t1, t2, t3, t4, t5, t6, t7 where t1.c11 = t2.c21 and t1.c12 = t3.c31 and t1.c13 = t4.c41 and t1.c14 = t5.c51 and t1.c15 = t6.c61 and t1.c16 = t7.c71 and t2.c22 = t3.c32 and t2.c23 = t4.c42 and t2.c24 = t5.c52 and t2.c25 = t6.c62 and t2.c26 = t7.c72 and t3.c33 = t4.c43 and t3.c34 = t5.c53 and t3.c35 = t6.c63 and t3.c36 = t7.c73 and t4.c42 = t5.c54 and t4.c43 = t6.c64 and t4.c44 = t7.c74 and t5.c52 = t6.c65 and t5.c53 = t7.c75 and t6.c62 = t7.c76;
 | 
						|
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 | 
						|
1	SIMPLE	t1	ALL	PRIMARY	NULL	NULL	NULL	3	
 | 
						|
1	SIMPLE	t2	ALL	NULL	NULL	NULL	NULL	6	Using where; Using join buffer
 | 
						|
1	SIMPLE	t3	eq_ref	PRIMARY	PRIMARY	4	test.t1.c12	1	Using where
 | 
						|
1	SIMPLE	t4	ALL	NULL	NULL	NULL	NULL	12	Using where; Using join buffer
 | 
						|
1	SIMPLE	t5	eq_ref	PRIMARY	PRIMARY	4	test.t1.c14	1	Using where
 | 
						|
1	SIMPLE	t6	ALL	NULL	NULL	NULL	NULL	18	Using where; Using join buffer
 | 
						|
1	SIMPLE	t7	eq_ref	PRIMARY	PRIMARY	4	test.t1.c16	1	Using where
 | 
						|
show status like 'Last_query_cost';
 | 
						|
Variable_name	Value
 | 
						|
Last_query_cost	794.837037
 | 
						|
explain select t1.c11 from t7, t6, t5, t4, t3, t2, t1 where t1.c11 = t2.c21 and t1.c12 = t3.c31 and t1.c13 = t4.c41 and t1.c14 = t5.c51 and t1.c15 = t6.c61 and t1.c16 = t7.c71 and t2.c22 = t3.c32 and t2.c23 = t4.c42 and t2.c24 = t5.c52 and t2.c25 = t6.c62 and t2.c26 = t7.c72 and t3.c33 = t4.c43 and t3.c34 = t5.c53 and t3.c35 = t6.c63 and t3.c36 = t7.c73 and t4.c42 = t5.c54 and t4.c43 = t6.c64 and t4.c44 = t7.c74 and t5.c52 = t6.c65 and t5.c53 = t7.c75 and t6.c62 = t7.c76;
 | 
						|
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 | 
						|
1	SIMPLE	t1	ALL	PRIMARY	NULL	NULL	NULL	3	
 | 
						|
1	SIMPLE	t2	ALL	NULL	NULL	NULL	NULL	6	Using where; Using join buffer
 | 
						|
1	SIMPLE	t3	eq_ref	PRIMARY	PRIMARY	4	test.t1.c12	1	Using where
 | 
						|
1	SIMPLE	t4	ALL	NULL	NULL	NULL	NULL	12	Using where; Using join buffer
 | 
						|
1	SIMPLE	t5	eq_ref	PRIMARY	PRIMARY	4	test.t1.c14	1	Using where
 | 
						|
1	SIMPLE	t6	ALL	NULL	NULL	NULL	NULL	18	Using where; Using join buffer
 | 
						|
1	SIMPLE	t7	eq_ref	PRIMARY	PRIMARY	4	test.t1.c16	1	Using where
 | 
						|
show status like 'Last_query_cost';
 | 
						|
Variable_name	Value
 | 
						|
Last_query_cost	794.837037
 | 
						|
set optimizer_search_depth=1;
 | 
						|
select @@optimizer_search_depth;
 | 
						|
@@optimizer_search_depth
 | 
						|
1
 | 
						|
explain select t1.c11 from t1, t2, t3, t4, t5, t6, t7 where t1.c12 = t2.c21 and t2.c22 = t3.c31 and t3.c32 = t4.c41 and t4.c42 = t5.c51 and t5.c52 = t6.c61 and t6.c62 = t7.c71;
 | 
						|
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 | 
						|
1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	3	
 | 
						|
1	SIMPLE	t2	ALL	NULL	NULL	NULL	NULL	6	Using where; Using join buffer
 | 
						|
1	SIMPLE	t3	eq_ref	PRIMARY	PRIMARY	4	test.t2.c22	1	
 | 
						|
1	SIMPLE	t4	ALL	NULL	NULL	NULL	NULL	12	Using where; Using join buffer
 | 
						|
1	SIMPLE	t5	eq_ref	PRIMARY	PRIMARY	4	test.t4.c42	1	
 | 
						|
1	SIMPLE	t6	ALL	NULL	NULL	NULL	NULL	18	Using where; Using join buffer
 | 
						|
1	SIMPLE	t7	eq_ref	PRIMARY	PRIMARY	4	test.t6.c62	1	Using index
 | 
						|
show status like 'Last_query_cost';
 | 
						|
Variable_name	Value
 | 
						|
Last_query_cost	821.837037
 | 
						|
explain select t1.c11 from t7, t6, t5, t4, t3, t2, t1 where t1.c12 = t2.c21 and t2.c22 = t3.c31 and t3.c32 = t4.c41 and t4.c42 = t5.c51 and t5.c52 = t6.c61 and t6.c62 = t7.c71;
 | 
						|
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 | 
						|
1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	3	
 | 
						|
1	SIMPLE	t2	ALL	NULL	NULL	NULL	NULL	6	Using where; Using join buffer
 | 
						|
1	SIMPLE	t3	eq_ref	PRIMARY	PRIMARY	4	test.t2.c22	1	
 | 
						|
1	SIMPLE	t4	ALL	NULL	NULL	NULL	NULL	12	Using where; Using join buffer
 | 
						|
1	SIMPLE	t5	eq_ref	PRIMARY	PRIMARY	4	test.t4.c42	1	
 | 
						|
1	SIMPLE	t6	ALL	NULL	NULL	NULL	NULL	18	Using where; Using join buffer
 | 
						|
1	SIMPLE	t7	eq_ref	PRIMARY	PRIMARY	4	test.t6.c62	1	Using index
 | 
						|
show status like 'Last_query_cost';
 | 
						|
Variable_name	Value
 | 
						|
Last_query_cost	821.837037
 | 
						|
explain select t1.c11 from t1, t2, t3, t4, t5, t6, t7 where t1.c11 = t2.c21 and t1.c12 = t3.c31 and t1.c13 = t4.c41 and t1.c14 = t5.c51 and t1.c15 = t6.c61 and t1.c16 = t7.c71;
 | 
						|
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 | 
						|
1	SIMPLE	t1	ALL	PRIMARY	NULL	NULL	NULL	3	
 | 
						|
1	SIMPLE	t3	eq_ref	PRIMARY	PRIMARY	4	test.t1.c12	1	Using index
 | 
						|
1	SIMPLE	t5	eq_ref	PRIMARY	PRIMARY	4	test.t1.c14	1	Using index
 | 
						|
1	SIMPLE	t7	eq_ref	PRIMARY	PRIMARY	4	test.t1.c16	1	Using index
 | 
						|
1	SIMPLE	t2	ALL	NULL	NULL	NULL	NULL	6	Using where; Using join buffer
 | 
						|
1	SIMPLE	t4	ALL	NULL	NULL	NULL	NULL	12	Using where; Using join buffer
 | 
						|
1	SIMPLE	t6	ALL	NULL	NULL	NULL	NULL	18	Using where; Using join buffer
 | 
						|
show status like 'Last_query_cost';
 | 
						|
Variable_name	Value
 | 
						|
Last_query_cost	794.837037
 | 
						|
explain select t1.c11 from t7, t6, t5, t4, t3, t2, t1 where t1.c11 = t2.c21 and t1.c12 = t3.c31 and t1.c13 = t4.c41 and t1.c14 = t5.c51 and t1.c15 = t6.c61 and t1.c16 = t7.c71;
 | 
						|
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 | 
						|
1	SIMPLE	t1	ALL	PRIMARY	NULL	NULL	NULL	3	
 | 
						|
1	SIMPLE	t3	eq_ref	PRIMARY	PRIMARY	4	test.t1.c12	1	Using index
 | 
						|
1	SIMPLE	t5	eq_ref	PRIMARY	PRIMARY	4	test.t1.c14	1	Using index
 | 
						|
1	SIMPLE	t7	eq_ref	PRIMARY	PRIMARY	4	test.t1.c16	1	Using index
 | 
						|
1	SIMPLE	t2	ALL	NULL	NULL	NULL	NULL	6	Using where; Using join buffer
 | 
						|
1	SIMPLE	t4	ALL	NULL	NULL	NULL	NULL	12	Using where; Using join buffer
 | 
						|
1	SIMPLE	t6	ALL	NULL	NULL	NULL	NULL	18	Using where; Using join buffer
 | 
						|
show status like 'Last_query_cost';
 | 
						|
Variable_name	Value
 | 
						|
Last_query_cost	794.837037
 | 
						|
explain select t1.c11 from t1, t2, t3, t4, t5, t6, t7 where t1.c11 = t2.c21 and t1.c12 = t3.c31 and t1.c13 = t4.c41 and t1.c14 = t5.c51 and t1.c15 = t6.c61 and t1.c16 = t7.c71 and t2.c22 = t3.c32 and t2.c23 = t4.c42 and t2.c24 = t5.c52 and t2.c25 = t6.c62 and t2.c26 = t7.c72 and t3.c33 = t4.c43 and t3.c34 = t5.c53 and t3.c35 = t6.c63 and t3.c36 = t7.c73 and t4.c42 = t5.c54 and t4.c43 = t6.c64 and t4.c44 = t7.c74 and t5.c52 = t6.c65 and t5.c53 = t7.c75 and t6.c62 = t7.c76;
 | 
						|
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 | 
						|
1	SIMPLE	t1	ALL	PRIMARY	NULL	NULL	NULL	3	
 | 
						|
1	SIMPLE	t3	eq_ref	PRIMARY	PRIMARY	4	test.t1.c12	1	
 | 
						|
1	SIMPLE	t5	eq_ref	PRIMARY	PRIMARY	4	test.t1.c14	1	Using where
 | 
						|
1	SIMPLE	t7	eq_ref	PRIMARY	PRIMARY	4	test.t1.c16	1	Using where
 | 
						|
1	SIMPLE	t2	ALL	NULL	NULL	NULL	NULL	6	Using where; Using join buffer
 | 
						|
1	SIMPLE	t4	ALL	NULL	NULL	NULL	NULL	12	Using where; Using join buffer
 | 
						|
1	SIMPLE	t6	ALL	NULL	NULL	NULL	NULL	18	Using where; Using join buffer
 | 
						|
show status like 'Last_query_cost';
 | 
						|
Variable_name	Value
 | 
						|
Last_query_cost	794.837037
 | 
						|
explain select t1.c11 from t7, t6, t5, t4, t3, t2, t1 where t1.c11 = t2.c21 and t1.c12 = t3.c31 and t1.c13 = t4.c41 and t1.c14 = t5.c51 and t1.c15 = t6.c61 and t1.c16 = t7.c71 and t2.c22 = t3.c32 and t2.c23 = t4.c42 and t2.c24 = t5.c52 and t2.c25 = t6.c62 and t2.c26 = t7.c72 and t3.c33 = t4.c43 and t3.c34 = t5.c53 and t3.c35 = t6.c63 and t3.c36 = t7.c73 and t4.c42 = t5.c54 and t4.c43 = t6.c64 and t4.c44 = t7.c74 and t5.c52 = t6.c65 and t5.c53 = t7.c75 and t6.c62 = t7.c76;
 | 
						|
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 | 
						|
1	SIMPLE	t1	ALL	PRIMARY	NULL	NULL	NULL	3	
 | 
						|
1	SIMPLE	t3	eq_ref	PRIMARY	PRIMARY	4	test.t1.c12	1	
 | 
						|
1	SIMPLE	t5	eq_ref	PRIMARY	PRIMARY	4	test.t1.c14	1	Using where
 | 
						|
1	SIMPLE	t7	eq_ref	PRIMARY	PRIMARY	4	test.t1.c16	1	Using where
 | 
						|
1	SIMPLE	t2	ALL	NULL	NULL	NULL	NULL	6	Using where; Using join buffer
 | 
						|
1	SIMPLE	t4	ALL	NULL	NULL	NULL	NULL	12	Using where; Using join buffer
 | 
						|
1	SIMPLE	t6	ALL	NULL	NULL	NULL	NULL	18	Using where; Using join buffer
 | 
						|
show status like 'Last_query_cost';
 | 
						|
Variable_name	Value
 | 
						|
Last_query_cost	794.837037
 | 
						|
set optimizer_search_depth=62;
 | 
						|
select @@optimizer_search_depth;
 | 
						|
@@optimizer_search_depth
 | 
						|
62
 | 
						|
explain select t1.c11 from t1, t2, t3, t4, t5, t6, t7 where t1.c12 = t2.c21 and t2.c22 = t3.c31 and t3.c32 = t4.c41 and t4.c42 = t5.c51 and t5.c52 = t6.c61 and t6.c62 = t7.c71;
 | 
						|
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 | 
						|
1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	3	
 | 
						|
1	SIMPLE	t2	ALL	NULL	NULL	NULL	NULL	6	Using where; Using join buffer
 | 
						|
1	SIMPLE	t3	eq_ref	PRIMARY	PRIMARY	4	test.t2.c22	1	
 | 
						|
1	SIMPLE	t4	ALL	NULL	NULL	NULL	NULL	12	Using where; Using join buffer
 | 
						|
1	SIMPLE	t5	eq_ref	PRIMARY	PRIMARY	4	test.t4.c42	1	
 | 
						|
1	SIMPLE	t6	ALL	NULL	NULL	NULL	NULL	18	Using where; Using join buffer
 | 
						|
1	SIMPLE	t7	eq_ref	PRIMARY	PRIMARY	4	test.t6.c62	1	Using index
 | 
						|
show status like 'Last_query_cost';
 | 
						|
Variable_name	Value
 | 
						|
Last_query_cost	821.837037
 | 
						|
explain select t1.c11 from t7, t6, t5, t4, t3, t2, t1 where t1.c12 = t2.c21 and t2.c22 = t3.c31 and t3.c32 = t4.c41 and t4.c42 = t5.c51 and t5.c52 = t6.c61 and t6.c62 = t7.c71;
 | 
						|
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 | 
						|
1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	3	
 | 
						|
1	SIMPLE	t2	ALL	NULL	NULL	NULL	NULL	6	Using where; Using join buffer
 | 
						|
1	SIMPLE	t3	eq_ref	PRIMARY	PRIMARY	4	test.t2.c22	1	
 | 
						|
1	SIMPLE	t4	ALL	NULL	NULL	NULL	NULL	12	Using where; Using join buffer
 | 
						|
1	SIMPLE	t5	eq_ref	PRIMARY	PRIMARY	4	test.t4.c42	1	
 | 
						|
1	SIMPLE	t6	ALL	NULL	NULL	NULL	NULL	18	Using where; Using join buffer
 | 
						|
1	SIMPLE	t7	eq_ref	PRIMARY	PRIMARY	4	test.t6.c62	1	Using index
 | 
						|
show status like 'Last_query_cost';
 | 
						|
Variable_name	Value
 | 
						|
Last_query_cost	821.837037
 | 
						|
explain select t1.c11 from t1, t2, t3, t4, t5, t6, t7 where t1.c11 = t2.c21 and t1.c12 = t3.c31 and t1.c13 = t4.c41 and t1.c14 = t5.c51 and t1.c15 = t6.c61 and t1.c16 = t7.c71;
 | 
						|
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 | 
						|
1	SIMPLE	t1	ALL	PRIMARY	NULL	NULL	NULL	3	
 | 
						|
1	SIMPLE	t2	ALL	NULL	NULL	NULL	NULL	6	Using where; Using join buffer
 | 
						|
1	SIMPLE	t3	eq_ref	PRIMARY	PRIMARY	4	test.t1.c12	1	Using index
 | 
						|
1	SIMPLE	t4	ALL	NULL	NULL	NULL	NULL	12	Using where; Using join buffer
 | 
						|
1	SIMPLE	t5	eq_ref	PRIMARY	PRIMARY	4	test.t1.c14	1	Using index
 | 
						|
1	SIMPLE	t6	ALL	NULL	NULL	NULL	NULL	18	Using where; Using join buffer
 | 
						|
1	SIMPLE	t7	eq_ref	PRIMARY	PRIMARY	4	test.t1.c16	1	Using index
 | 
						|
show status like 'Last_query_cost';
 | 
						|
Variable_name	Value
 | 
						|
Last_query_cost	794.837037
 | 
						|
explain select t1.c11 from t7, t6, t5, t4, t3, t2, t1 where t1.c11 = t2.c21 and t1.c12 = t3.c31 and t1.c13 = t4.c41 and t1.c14 = t5.c51 and t1.c15 = t6.c61 and t1.c16 = t7.c71;
 | 
						|
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 | 
						|
1	SIMPLE	t1	ALL	PRIMARY	NULL	NULL	NULL	3	
 | 
						|
1	SIMPLE	t2	ALL	NULL	NULL	NULL	NULL	6	Using where; Using join buffer
 | 
						|
1	SIMPLE	t3	eq_ref	PRIMARY	PRIMARY	4	test.t1.c12	1	Using index
 | 
						|
1	SIMPLE	t4	ALL	NULL	NULL	NULL	NULL	12	Using where; Using join buffer
 | 
						|
1	SIMPLE	t5	eq_ref	PRIMARY	PRIMARY	4	test.t1.c14	1	Using index
 | 
						|
1	SIMPLE	t6	ALL	NULL	NULL	NULL	NULL	18	Using where; Using join buffer
 | 
						|
1	SIMPLE	t7	eq_ref	PRIMARY	PRIMARY	4	test.t1.c16	1	Using index
 | 
						|
show status like 'Last_query_cost';
 | 
						|
Variable_name	Value
 | 
						|
Last_query_cost	794.837037
 | 
						|
explain select t1.c11 from t1, t2, t3, t4, t5, t6, t7 where t1.c11 = t2.c21 and t1.c12 = t3.c31 and t1.c13 = t4.c41 and t1.c14 = t5.c51 and t1.c15 = t6.c61 and t1.c16 = t7.c71 and t2.c22 = t3.c32 and t2.c23 = t4.c42 and t2.c24 = t5.c52 and t2.c25 = t6.c62 and t2.c26 = t7.c72 and t3.c33 = t4.c43 and t3.c34 = t5.c53 and t3.c35 = t6.c63 and t3.c36 = t7.c73 and t4.c42 = t5.c54 and t4.c43 = t6.c64 and t4.c44 = t7.c74 and t5.c52 = t6.c65 and t5.c53 = t7.c75 and t6.c62 = t7.c76;
 | 
						|
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 | 
						|
1	SIMPLE	t1	ALL	PRIMARY	NULL	NULL	NULL	3	
 | 
						|
1	SIMPLE	t2	ALL	NULL	NULL	NULL	NULL	6	Using where; Using join buffer
 | 
						|
1	SIMPLE	t3	eq_ref	PRIMARY	PRIMARY	4	test.t1.c12	1	Using where
 | 
						|
1	SIMPLE	t4	ALL	NULL	NULL	NULL	NULL	12	Using where; Using join buffer
 | 
						|
1	SIMPLE	t5	eq_ref	PRIMARY	PRIMARY	4	test.t1.c14	1	Using where
 | 
						|
1	SIMPLE	t6	ALL	NULL	NULL	NULL	NULL	18	Using where; Using join buffer
 | 
						|
1	SIMPLE	t7	eq_ref	PRIMARY	PRIMARY	4	test.t1.c16	1	Using where
 | 
						|
show status like 'Last_query_cost';
 | 
						|
Variable_name	Value
 | 
						|
Last_query_cost	794.837037
 | 
						|
explain select t1.c11 from t7, t6, t5, t4, t3, t2, t1 where t1.c11 = t2.c21 and t1.c12 = t3.c31 and t1.c13 = t4.c41 and t1.c14 = t5.c51 and t1.c15 = t6.c61 and t1.c16 = t7.c71 and t2.c22 = t3.c32 and t2.c23 = t4.c42 and t2.c24 = t5.c52 and t2.c25 = t6.c62 and t2.c26 = t7.c72 and t3.c33 = t4.c43 and t3.c34 = t5.c53 and t3.c35 = t6.c63 and t3.c36 = t7.c73 and t4.c42 = t5.c54 and t4.c43 = t6.c64 and t4.c44 = t7.c74 and t5.c52 = t6.c65 and t5.c53 = t7.c75 and t6.c62 = t7.c76;
 | 
						|
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 | 
						|
1	SIMPLE	t1	ALL	PRIMARY	NULL	NULL	NULL	3	
 | 
						|
1	SIMPLE	t2	ALL	NULL	NULL	NULL	NULL	6	Using where; Using join buffer
 | 
						|
1	SIMPLE	t3	eq_ref	PRIMARY	PRIMARY	4	test.t1.c12	1	Using where
 | 
						|
1	SIMPLE	t4	ALL	NULL	NULL	NULL	NULL	12	Using where; Using join buffer
 | 
						|
1	SIMPLE	t5	eq_ref	PRIMARY	PRIMARY	4	test.t1.c14	1	Using where
 | 
						|
1	SIMPLE	t6	ALL	NULL	NULL	NULL	NULL	18	Using where; Using join buffer
 | 
						|
1	SIMPLE	t7	eq_ref	PRIMARY	PRIMARY	4	test.t1.c16	1	Using where
 | 
						|
show status like 'Last_query_cost';
 | 
						|
Variable_name	Value
 | 
						|
Last_query_cost	794.837037
 | 
						|
drop table t1,t2,t3,t4,t5,t6,t7;
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