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From: Adam Lee <ali@pivotal.io>
To: Jeff Davis <pgsql@j-davis.com>
Cc: Peter Geoghegan <pg@bowt.ie>
Cc: Heikki Linnakangas <hlinnaka@iki.fi>
Cc: Tomas Vondra <tomas.vondra@2ndquadrant.com>
Cc: Taylor Vesely <tvesely@pivotal.io>
Cc: Melanie Plageman <mplageman@pivotal.io>
Cc: PostgreSQL Hackers <pgsql-hackers@postgresql.org>
Subject: Re: Memory-Bounded Hash Aggregation
Date: Tue, 4 Feb 2020 18:42:29 +0800
Message-ID: <20200204104229.GA58298@earth.local> (raw)
In-Reply-To: <8bf8d5f77db49cc1f032b6c7c0cfe0d6da89d64a.camel@j-davis.com>
References: <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>
	<e5566f7def33a9e9fdff337cca32d07155d7b635.camel@j-davis.com>
	<CAH2-WznXPuKOee6EMxc7jD4vSQv=yFVVTz6gridGkmzxTSkyNA@mail.gmail.com>
	<6e2b4a4475a690fa515829950aeed935696b0df3.camel@j-davis.com>
	<97c46a59c27f3c38e486ca170fcbc618d97ab049.camel@j-davis.com>
	<8bf8d5f77db49cc1f032b6c7c0cfe0d6da89d64a.camel@j-davis.com>

On Mon, Feb 03, 2020 at 06:24:14PM -0800, Jeff Davis wrote:
> On Mon, 2020-02-03 at 10:29 -0800, Jeff Davis wrote:
> > I ended up converting the freelist to a min heap.
> > 
> > Attached is a patch which makes three changes to better support
> > HashAgg:
> 
> And now I'm attaching another version of the main Hash Aggregation
> patch to be applied on top of the logtape.c patch.
> 
> Not a lot of changes from the last version; mostly some cleanup and
> rebasing. But it's faster now with the logtape.c changes.

Nice!

Just back from the holiday. I had the perf test with Tomas's script,
didn't notice the freelist sorting regression at that time.

The minheap looks good, have you tested the performance and aggregate
validation?

About the "Cap the size of the LogicalTapeSet's freelist" and "Don't
bother tracking free space for HashAgg at all" you mentioned in last
mail, I suppose these two options will lost the disk space saving
benefit since some blocks are not reusable then?

-- 
Adam Lee





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