892
892
explain extended SELECT t1.a, t1.a in (select t2.a from t2,t3 where t3.a=t2.a) FROM t1;
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893
id select_type table type possible_keys key key_len ref rows filtered Extra
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894
1 PRIMARY t1 index NULL PRIMARY 4 NULL 4 100.00 Using index
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896
2 DEPENDENT SUBQUERY t3 ALL NULL NULL NULL NULL 3 100.00 Using where; Using join buffer
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898
Note 1003 select `test`.`t1`.`a` AS `a`,<in_optimizer>(`test`.`t1`.`a`,<exists>(select 1 AS `Not_used` from `test`.`t2` join `test`.`t3` where ((`test`.`t3`.`a` = `test`.`t2`.`a`) and ((<cache>(`test`.`t1`.`a`) = `test`.`t2`.`a`) or isnull(`test`.`t2`.`a`))) having <is_not_null_test>(`test`.`t2`.`a`))) AS `t1.a in (select t2.a from t2,t3 where t3.a=t2.a)` from `test`.`t1`