Horton

Re: Poor memory context performance in large hash joins

Andres Freund <andres@anarazel.de>

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From: Andres Freund <andres@anarazel.de>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Jeff Janes <jeff.janes@gmail.com>, pgsql-hackers <pgsql-hackers@postgresql.org>
Date: 2017-02-24T23:12:37Z
Lists: pgsql-hackers 
On 2017-02-24 18:04:18 -0500, Tom Lane wrote:
> Concretely, something like the attached.  This passes regression tests
> but I've not pushed on it any harder than that.

Heh, I'd just gotten something that didn't immediately crash anymore ;)

Running your patch against Jeff's test-case, verified before that I
could easily reproduce the O(N^2) cost.

- Andres

Commits

  1. Use doubly-linked block lists in aset.c to reduce large-chunk overhead.