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@ -5656,4 +5656,153 @@ 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 10 |
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1 SIMPLE t2 ALL NULL NULL NULL NULL 10 Using where; Using join buffer (flat, BNL join) |
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drop table t0,t1,t2; |
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# |
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# mdev-6292: huge performance degradation for a sequence |
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# of LEFT JOIN operations when using join buffer |
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# |
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CREATE TABLE t1 ( |
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id int(11) NOT NULL AUTO_INCREMENT, |
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col1 varchar(255) NOT NULL DEFAULT '', |
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PRIMARY KEY (id) |
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) ENGINE=INNODB; |
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CREATE TABLE t2 ( |
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id int(11) NOT NULL AUTO_INCREMENT, |
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parent_id smallint(3) NOT NULL DEFAULT '0', |
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col2 varchar(25) NOT NULL DEFAULT '', |
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PRIMARY KEY (id) |
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) ENGINE=INNODB; |
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set join_buffer_size=8192; |
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set join_cache_level=0; |
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set @init_time:=now(); |
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SELECT t.* |
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FROM |
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t1 t |
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LEFT JOIN t2 c1 ON c1.parent_id = t.id AND c1.col2 = "val" |
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LEFT JOIN t2 c2 ON c2.parent_id = t.id AND c2.col2 = "val" |
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LEFT JOIN t2 c3 ON c3.parent_id = t.id AND c3.col2 = "val" |
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LEFT JOIN t2 c4 ON c4.parent_id = t.id AND c4.col2 = "val" |
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LEFT JOIN t2 c5 ON c5.parent_id = t.id AND c5.col2 = "val" |
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LEFT JOIN t2 c6 ON c6.parent_id = t.id AND c6.col2 = "val" |
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LEFT JOIN t2 c7 ON c7.parent_id = t.id AND c7.col2 = "val" |
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LEFT JOIN t2 c8 ON c8.parent_id = t.id AND c8.col2 = "val" |
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LEFT JOIN t2 c9 ON c9.parent_id = t.id AND c9.col2 = "val" |
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LEFT JOIN t2 c10 ON c10.parent_id = t.id AND c10.col2 = "val" |
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LEFT JOIN t2 c11 ON c11.parent_id = t.id AND c11.col2 = "val" |
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LEFT JOIN t2 c12 ON c12.parent_id = t.id AND c12.col2 = "val" |
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LEFT JOIN t2 c13 ON c13.parent_id = t.id AND c13.col2 = "val" |
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LEFT JOIN t2 c14 ON c14.parent_id = t.id AND c14.col2 = "val" |
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LEFT JOIN t2 c15 ON c15.parent_id = t.id AND c15.col2 = "val" |
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LEFT JOIN t2 c16 ON c16.parent_id = t.id AND c16.col2 = "val" |
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LEFT JOIN t2 c17 ON c17.parent_id = t.id AND c17.col2 = "val" |
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LEFT JOIN t2 c18 ON c18.parent_id = t.id AND c18.col2 = "val" |
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LEFT JOIN t2 c19 ON c19.parent_id = t.id AND c19.col2 = "val" |
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LEFT JOIN t2 c20 ON c20.parent_id = t.id AND c20.col2 = "val" |
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LEFT JOIN t2 c21 ON c21.parent_id = t.id AND c21.col2 = "val" |
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LEFT JOIN t2 c22 ON c22.parent_id = t.id AND c22.col2 = "val" |
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LEFT JOIN t2 c23 ON c23.parent_id = t.id AND c23.col2 = "val" |
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LEFT JOIN t2 c24 ON c24.parent_id = t.id AND c24.col2 = "val" |
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LEFT JOIN t2 c25 ON c25.parent_id = t.id AND c25.col2 = "val" |
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ORDER BY |
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col1; |
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id col1 |
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select timestampdiff(second, @init_time, now()) <= 1; |
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timestampdiff(second, @init_time, now()) <= 1 |
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1 |
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set join_cache_level=2; |
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set @init_time:=now(); |
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SELECT t.* |
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FROM |
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t1 t |
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LEFT JOIN t2 c1 ON c1.parent_id = t.id AND c1.col2 = "val" |
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LEFT JOIN t2 c2 ON c2.parent_id = t.id AND c2.col2 = "val" |
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LEFT JOIN t2 c3 ON c3.parent_id = t.id AND c3.col2 = "val" |
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LEFT JOIN t2 c4 ON c4.parent_id = t.id AND c4.col2 = "val" |
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LEFT JOIN t2 c5 ON c5.parent_id = t.id AND c5.col2 = "val" |
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LEFT JOIN t2 c6 ON c6.parent_id = t.id AND c6.col2 = "val" |
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LEFT JOIN t2 c7 ON c7.parent_id = t.id AND c7.col2 = "val" |
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LEFT JOIN t2 c8 ON c8.parent_id = t.id AND c8.col2 = "val" |
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LEFT JOIN t2 c9 ON c9.parent_id = t.id AND c9.col2 = "val" |
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LEFT JOIN t2 c10 ON c10.parent_id = t.id AND c10.col2 = "val" |
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LEFT JOIN t2 c11 ON c11.parent_id = t.id AND c11.col2 = "val" |
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LEFT JOIN t2 c12 ON c12.parent_id = t.id AND c12.col2 = "val" |
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LEFT JOIN t2 c13 ON c13.parent_id = t.id AND c13.col2 = "val" |
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LEFT JOIN t2 c14 ON c14.parent_id = t.id AND c14.col2 = "val" |
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LEFT JOIN t2 c15 ON c15.parent_id = t.id AND c15.col2 = "val" |
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LEFT JOIN t2 c16 ON c16.parent_id = t.id AND c16.col2 = "val" |
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LEFT JOIN t2 c17 ON c17.parent_id = t.id AND c17.col2 = "val" |
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LEFT JOIN t2 c18 ON c18.parent_id = t.id AND c18.col2 = "val" |
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LEFT JOIN t2 c19 ON c19.parent_id = t.id AND c19.col2 = "val" |
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LEFT JOIN t2 c20 ON c20.parent_id = t.id AND c20.col2 = "val" |
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LEFT JOIN t2 c21 ON c21.parent_id = t.id AND c21.col2 = "val" |
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LEFT JOIN t2 c22 ON c22.parent_id = t.id AND c22.col2 = "val" |
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LEFT JOIN t2 c23 ON c23.parent_id = t.id AND c23.col2 = "val" |
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LEFT JOIN t2 c24 ON c24.parent_id = t.id AND c24.col2 = "val" |
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LEFT JOIN t2 c25 ON c25.parent_id = t.id AND c25.col2 = "val" |
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ORDER BY |
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col1; |
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id col1 |
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select timestampdiff(second, @init_time, now()) <= 1; |
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timestampdiff(second, @init_time, now()) <= 1 |
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1 |
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EXPLAIN |
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SELECT t.* |
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FROM |
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t1 t |
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LEFT JOIN t2 c1 ON c1.parent_id = t.id AND c1.col2 = "val" |
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LEFT JOIN t2 c2 ON c2.parent_id = t.id AND c2.col2 = "val" |
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LEFT JOIN t2 c3 ON c3.parent_id = t.id AND c3.col2 = "val" |
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LEFT JOIN t2 c4 ON c4.parent_id = t.id AND c4.col2 = "val" |
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LEFT JOIN t2 c5 ON c5.parent_id = t.id AND c5.col2 = "val" |
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LEFT JOIN t2 c6 ON c6.parent_id = t.id AND c6.col2 = "val" |
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LEFT JOIN t2 c7 ON c7.parent_id = t.id AND c7.col2 = "val" |
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LEFT JOIN t2 c8 ON c8.parent_id = t.id AND c8.col2 = "val" |
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LEFT JOIN t2 c9 ON c9.parent_id = t.id AND c9.col2 = "val" |
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LEFT JOIN t2 c10 ON c10.parent_id = t.id AND c10.col2 = "val" |
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LEFT JOIN t2 c11 ON c11.parent_id = t.id AND c11.col2 = "val" |
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LEFT JOIN t2 c12 ON c12.parent_id = t.id AND c12.col2 = "val" |
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LEFT JOIN t2 c13 ON c13.parent_id = t.id AND c13.col2 = "val" |
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LEFT JOIN t2 c14 ON c14.parent_id = t.id AND c14.col2 = "val" |
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LEFT JOIN t2 c15 ON c15.parent_id = t.id AND c15.col2 = "val" |
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LEFT JOIN t2 c16 ON c16.parent_id = t.id AND c16.col2 = "val" |
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LEFT JOIN t2 c17 ON c17.parent_id = t.id AND c17.col2 = "val" |
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LEFT JOIN t2 c18 ON c18.parent_id = t.id AND c18.col2 = "val" |
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LEFT JOIN t2 c19 ON c19.parent_id = t.id AND c19.col2 = "val" |
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LEFT JOIN t2 c20 ON c20.parent_id = t.id AND c20.col2 = "val" |
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LEFT JOIN t2 c21 ON c21.parent_id = t.id AND c21.col2 = "val" |
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LEFT JOIN t2 c22 ON c22.parent_id = t.id AND c22.col2 = "val" |
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LEFT JOIN t2 c23 ON c23.parent_id = t.id AND c23.col2 = "val" |
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LEFT JOIN t2 c24 ON c24.parent_id = t.id AND c24.col2 = "val" |
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LEFT JOIN t2 c25 ON c25.parent_id = t.id AND c25.col2 = "val" |
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ORDER BY |
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col1; |
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id select_type table type possible_keys key key_len ref rows Extra |
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1 SIMPLE t ALL NULL NULL NULL NULL 1 Using temporary; Using filesort |
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1 SIMPLE c1 ALL NULL NULL NULL NULL 1 Using where; Using join buffer (flat, BNL join) |
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1 SIMPLE c2 ALL NULL NULL NULL NULL 1 Using where; Using join buffer (incremental, BNL join) |
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1 SIMPLE c3 ALL NULL NULL NULL NULL 1 Using where; Using join buffer (incremental, BNL join) |
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1 SIMPLE c4 ALL NULL NULL NULL NULL 1 Using where; Using join buffer (incremental, BNL join) |
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1 SIMPLE c5 ALL NULL NULL NULL NULL 1 Using where; Using join buffer (incremental, BNL join) |
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1 SIMPLE c6 ALL NULL NULL NULL NULL 1 Using where; Using join buffer (incremental, BNL join) |
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1 SIMPLE c7 ALL NULL NULL NULL NULL 1 Using where; Using join buffer (incremental, BNL join) |
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1 SIMPLE c8 ALL NULL NULL NULL NULL 1 Using where; Using join buffer (incremental, BNL join) |
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1 SIMPLE c9 ALL NULL NULL NULL NULL 1 Using where; Using join buffer (incremental, BNL join) |
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1 SIMPLE c10 ALL NULL NULL NULL NULL 1 Using where; Using join buffer (incremental, BNL join) |
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1 SIMPLE c11 ALL NULL NULL NULL NULL 1 Using where; Using join buffer (incremental, BNL join) |
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1 SIMPLE c12 ALL NULL NULL NULL NULL 1 Using where; Using join buffer (incremental, BNL join) |
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1 SIMPLE c13 ALL NULL NULL NULL NULL 1 Using where; Using join buffer (incremental, BNL join) |
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1 SIMPLE c14 ALL NULL NULL NULL NULL 1 Using where; Using join buffer (incremental, BNL join) |
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1 SIMPLE c15 ALL NULL NULL NULL NULL 1 Using where; Using join buffer (incremental, BNL join) |
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1 SIMPLE c16 ALL NULL NULL NULL NULL 1 Using where; Using join buffer (incremental, BNL join) |
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1 SIMPLE c17 ALL NULL NULL NULL NULL 1 Using where; Using join buffer (incremental, BNL join) |
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1 SIMPLE c18 ALL NULL NULL NULL NULL 1 Using where; Using join buffer (incremental, BNL join) |
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1 SIMPLE c19 ALL NULL NULL NULL NULL 1 Using where; Using join buffer (incremental, BNL join) |
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1 SIMPLE c20 ALL NULL NULL NULL NULL 1 Using where; Using join buffer (incremental, BNL join) |
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1 SIMPLE c21 ALL NULL NULL NULL NULL 1 Using where; Using join buffer (incremental, BNL join) |
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1 SIMPLE c22 ALL NULL NULL NULL NULL 1 Using where; Using join buffer (incremental, BNL join) |
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1 SIMPLE c23 ALL NULL NULL NULL NULL 1 Using where; Using join buffer (incremental, BNL join) |
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1 SIMPLE c24 ALL NULL NULL NULL NULL 1 Using where; Using join buffer (incremental, BNL join) |
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1 SIMPLE c25 ALL NULL NULL NULL NULL 1 Using where; Using join buffer (incremental, BNL join) |
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set join_buffer_size=default; |
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set join_cache_level = default; |
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DROP TABLE t1,t2; |
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set @@optimizer_switch=@save_optimizer_switch; |