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|From:||Guilhem Bichot||Date:||June 30 2010 1:43pm|
|Subject:||Re: bzr commit into mysql-next-mr-opt-backporting branch|
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Hello, Jørgen Løland a écrit, Le 30.06.2010 15:03: > Guilhem, > > I'm doing my best to understand the consequences of removing the for(;;) > loop and tried a few queries. Here's what I found so far: > > #Your query > select t2.a from t2 left join t3 on t2.a=t3.a; > a > 1 > 1 > select * from t1 where t1.a in (select t2.a from t2 left join t3 on > t2.a=t3.a); > a > 1 > 1 > > #Modified query with inner cross-join - should be same result > select t2.a from t2 left join (t2 as t2inner,t3) on t2.a=t3.a; > a > 1 > 1 > select * from t1 where t1.a in (select t2.a from t2 left join (t2 as > t2inner,t3) on t2.a=t3.a); > a > 1 > > Do you agree that the result of the last query misses a '1' row? Yes :-( Without the patch, the query has 4 rows (wrong); with the patch it has one row (wrong too). Thanks for the good catch, I'll rework that.