Re: bzr commit into mysql-next-mr-opt-backporting branch (guilhem:3208) Bug#54437

[Guilhem Bichot]

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.