Re: -HEAD planner issue wrt hash_joins on dbt3 ? - Mailing list pgsql-hackers

From Stefan Kaltenbrunner
Subject Re: -HEAD planner issue wrt hash_joins on dbt3 ?
Date
Msg-id 451415A0.2090608@kaltenbrunner.cc
Whole thread Raw
In response to Re: -HEAD planner issue wrt hash_joins on dbt3 ?  (Tom Lane <tgl@sss.pgh.pa.us>)
List pgsql-hackers
Tom Lane wrote:
> Matteo Beccati <php@beccati.com> writes:
>> Tom Lane ha scritto:
>>> Matteo Beccati <php@beccati.com> writes:
>>>> I cannot see anything bad by using something like that:
>>>> if (histogram is large/representative enough)
>>> Well, the question is exactly what is "large enough"?  I feel a bit
>>> uncomfortable about applying the idea to a histogram with only 10
>>> entries (especially if we ignore two of 'em).  With 100 or more,
>>> it sounds all right.  What's the breakpoint?
> 
>> Yes, I think 100-200 could be a good breakpoint.
> 
> I've committed this change with (for now) 100 as the minimum histogram
> size to use.  Stefan, are you interested in retrying your benchmark?

sure - but I'm having hardware (harddisk firmware) related issues on my
testbox which will take a few further days to be resolved ...


Stefan


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