explain select * from v1 where v1.c1 in
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(select max(a.c1) from t1 a where a.c2 = v1.c2) and c3 = 5;
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id select_type table type possible_keys key key_len ref rows Extra
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-1 PRIMARY t1 ALL t1_c2 NULL NULL NULL 32 Using where
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+1 PRIMARY t1 ref t1_c2 t1_c2 5 const 8 Using where
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2 DEPENDENT SUBQUERY a ref t1_c2 t1_c2 5 test.t1.c2 5 Using index
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explain delete from v1 where v1.c1 in
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(select max(a.c1) from t1 a where a.c2 = v1.c2) and c3 = 5;
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id select_type table type possible_keys key key_len ref rows Extra
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-1 PRIMARY t1 ALL t1_c2 NULL NULL NULL 32 Using where
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+1 PRIMARY t1 ref t1_c2 t1_c2 5 const 8 Using where
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2 DEPENDENT SUBQUERY a ref t1_c2 t1_c2 5 test.t1.c2 5 Using index
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delete from v1 where v1.c1 in
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(select max(a.c1) from t1 a where a.c2 = v1.c2) and c3 = 5;
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InnoDB unpredictable plan.txt