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From:Guilhem Bichot Date:August 31 2010 9:18am
Subject:Re: bzr commit into mysql-5.1-bugteam branch (martin.hansson:3478)
Bug#51070
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Hello,

Martin Hansson a écrit, Le 30.08.2010 11:33:
>  Guilhem Bichot skrev 2010-08-25 19.50:
>> Hello Martin,
>>
>> Martin Hansson a écrit, Le 06.08.2010 15:26:
>>> #At file:///data0/martin/bzr/bug51070/5.1bt-guilhem/ based on 
>>> revid:bjorn.munch@stripped
>>>
>>>  3478 Martin Hansson    2010-08-06
>>>       Bug#51070: Query with a NOT IN subquery predicate returns a 
>>> wrong result set


>> The code itself is ok to push. Tests' results seem ok (I guess they 
>> would fail without the code fix?).
> That is your job to make sure ;-)

ok, will check.

>> If QA had a RQG grammar about partial matches, or could quickly write 
>> one, it would be good to run it... it's hard to be 100% sure about 
>> fixes to this subselect code.

> Good idea. Who is doing that stuff nowadays?

John Embretsen is the RQG guy nowadays.

> Actually I think most of 
> this code should be removed and replaced with semijoin, flattening, or 
> materialization because they are all superior.

yes, but it seems that at least semijoin and materialization cannot be 
applied in certain cases _in_the_current_state_of_code_.
For example, materialization doesn't yet work with partial matches, 
fixing this is todo: 
https://intranet.mysql.com/worklog/Server-BackLog/?tid=3830
also described in "1.1 Subquery engine for hash semi-joins"
of
https://intranet.mysql.com/worklog/Server-Sprint/?tid=1110

I don't know whether there is a theoretical impossibility to replace all 
IN->EXISTS with the new optimizer features (assuming we would implement 
all the missing parts like WL#3830).

> IMHO there's no need to 
> have an inferior solution hanging about that is near impossible to 
> maintain and just as buggy. I'll ask the team about it.
> 
> Best Regards
> 
> Martin


-- 
Mr. Guilhem Bichot <guilhem.bichot@stripped>
Oracle / MySQL / Optimizer team, Lead Software Engineer
Bordeaux, France
www.oracle.com / www.mysql.com
Thread
Re: bzr commit into mysql-5.1-bugteam branch (martin.hansson:3478)Bug#51070Guilhem Bichot25 Aug
  • Re: bzr commit into mysql-5.1-bugteam branch (martin.hansson:3478)Bug#51070Roy Lyseng25 Aug
  • Re: bzr commit into mysql-5.1-bugteam branch (martin.hansson:3478)Bug#51070Martin Hansson30 Aug
    • Re: bzr commit into mysql-5.1-bugteam branch (martin.hansson:3478)Bug#51070Guilhem Bichot31 Aug
      • Re: bzr commit into mysql-5.1-bugteam branch (martin.hansson:3478)Bug#51070Roy Lyseng31 Aug