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From: Adam Lee <ali@pivotal.io>
To: Tomas Vondra <tomas.vondra@2ndquadrant.com>
Cc: Jeff Davis <pgsql@j-davis.com>
Cc: Melanie Plageman <melanieplageman@gmail.com>
Cc: Heikki Linnakangas <hlinnaka@iki.fi>
Cc: Taylor Vesely <tvesely@pivotal.io>
Cc: Melanie Plageman <mplageman@pivotal.io>
Cc: Pg Hackers <pgsql-hackers@postgresql.org>
Subject: Re: Memory-Bounded Hash Aggregation
Date: Thu, 20 Feb 2020 12:04:37 +0800
Message-ID: <20200220040437.GA4389@earth.local> (raw)
In-Reply-To: <20200219191636.gvdywx32kwbix6kd@development>
References: <20190802152123.ichmacgx3y3x7dc3@development>
	<CAFaX_4Ls5UGQ2UDYkWhn2xFq=V6BKpUbKSQnWmy27VWhQ2=enA@mail.gmail.com>
	<e52707d4665e32867fb6dd181825ef15f853b8bf.camel@j-davis.com>
	<20191214173225.3kzsbncr6brpxdll@development>
	<d72e494db7b075ef02c3163e6614e698701d2c3e.camel@j-davis.com>
	<775d754c-9a61-5363-6998-f87d15f1b592@iki.fi>
	<CAAKRu_aefEsv+UkQWqu+ioEnoiL2LJu9Diuh9BR8MbyXuZ0j4A@mail.gmail.com>
	<20200218185749.srk733n4z57lzxf2@development>
	<7612ea4d636b6341d0606f4e852d584798e04901.camel@j-davis.com>
	<20200219191636.gvdywx32kwbix6kd@development>

On Wed, Feb 19, 2020 at 08:16:36PM +0100, Tomas Vondra wrote:
> 4) lookup_hash_entries says
> 
>   /* check to see if we need to spill the tuple for this grouping set */
> 
> But that seems bogus, because AFAIK we can't spill tuples for grouping
> sets. So maybe this should say just "grouping"?

As I see it, it does traverse all hash sets, fill the hash table and
spill if needed, for each tuple.

The segfault is probably related to this and MixedAggregate, I'm looking
into it.

-- 
Adam Lee

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