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From:Guilhem Bichot Date:August 3 2010 8:28am
Subject:Re: bzr commit into mysql-next-mr-opt-backporting branch (roy.lyseng:3222)
Bug#51457
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Hello Roy,

Roy Lyseng a écrit, Le 03.08.2010 09:42:
> #At file:///home/rl136806/mysql/repo/mysql-work2/ based on
> revid:roy.lyseng@stripped
> 
>  3222 Roy Lyseng	2010-08-03
>       Bug#51457: Firstmatch semijoin strategy gives wrong results for
>                  certain query plans
>       
>       When the optimizer selects a semijoin FirstMatch plan that has
>       non-correlated tables interspersed with inner tables, the "jumps"
>       are placed so that execution might become incorrect.
>       Example: A query with an outer correlated table ot, a non-correlated
>       table nt and two inner tables it1 and it2 are used in a query and the
>       optimizer chooses the FirstMatch join order ot - it1 - nt - it2.
>       The optimizer assigns a "jump" from table it2 to ot. This strategy will
>       omit duplicates resulting from table nt.
>       
>       The fix assures that the jump from the last table in a consecutive
>       range of inner table goes to the most immediately preceeding outer
>       table (regardless of whether the outer table is correlated or not).
>       In this case, there are two consecutive ranges of inner tables:
>       {it1} and {it2}. In the first range, the last inner table is it1, the
>       jump should be to table ot. In the second range, the jump from it2
>       should be to nt.

ok to push, thanks.
Thread
bzr commit into mysql-next-mr-opt-backporting branch (roy.lyseng:3222)Bug#51457Roy Lyseng3 Aug
  • Re: bzr commit into mysql-next-mr-opt-backporting branch (roy.lyseng:3222)Bug#51457Guilhem Bichot3 Aug
  • Re: bzr commit into mysql-next-mr-opt-backporting branch (roy.lyseng:3222)Bug#51457Olav Sandstaa3 Aug
    • Re: bzr commit into mysql-next-mr-opt-backporting branch (roy.lyseng:3222)Bug#51457Roy Lyseng3 Aug