Re: tweaking NTUP_PER_BUCKET - Mailing list pgsql-hackers

From Tomas Vondra
Subject Re: tweaking NTUP_PER_BUCKET
Date
Msg-id 53C11F61.2030205@fuzzy.cz
Whole thread Raw
In response to Re: tweaking NTUP_PER_BUCKET  (Simon Riggs <simon@2ndQuadrant.com>)
Responses Re: tweaking NTUP_PER_BUCKET  (Simon Riggs <simon@2ndQuadrant.com>)
List pgsql-hackers
On 12.7.2014 11:39, Simon Riggs wrote:
> On 11 July 2014 18:25, Tomas Vondra <tv@fuzzy.cz> wrote:
> 
>> Turns out getting this working properly will quite complicated.
> 
> Lets keep this patch simple then. Later research can be another patch.

Well, the dense allocation is independent to the NTUP_PER_BUCKET
changes, and only happened to be discussed here because it's related to
hash joins. My plan was to keep it as a separate patch, thus not making
the NTUP patch any more complex.

> In terms of memory pressure, having larger joins go x4 faster has a 
> much more significant reducing effect on memory pressure than
> anything else. So my earlier concerns seem less of a concern.

OK.

> So lets just this change done and then do more later.

There's no way back, sadly. The dense allocation turned into a
challenge. I like challenges. I have to solve it or I won't be able to
sleep.

regards
Tomas



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