Re: Boom filters for hash joins (was: A design for amcheck heapam verification)

From: Peter Geoghegan <pg(at)bowt(dot)ie>
To: Tomas Vondra <tomas(dot)vondra(at)2ndquadrant(dot)com>
Cc: Robert Haas <robertmhaas(at)gmail(dot)com>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Thomas Munro <thomas(dot)munro(at)enterprisedb(dot)com>, PostgreSQL Hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Boom filters for hash joins (was: A design for amcheck heapam verification)
Date: 2017-09-19 16:03:43
Message-ID: CAH2-Wzn+xeU+CsrinrSBj014zmKCicbccAn-WmRe=Xx_VuFBpQ@mail.gmail.com
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On Tue, Sep 19, 2017 at 6:28 AM, Tomas Vondra
<tomas(dot)vondra(at)2ndquadrant(dot)com> wrote:
> The patch is fairly simple, and did not try to push the bloom filters to
> scan nodes or anything like that. It might be a meaningful first step,
> though, particularly for selective joins (where only small number of
> rows from the outer relation has a match in the hash table).

I believe that parallelism makes the use of Bloom filter a lot more
compelling, too. Obviously this is something that wasn't taken into
consideration in 2015.

--
Peter Geoghegan

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