From: | Robert Haas <robertmhaas(at)gmail(dot)com> |
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To: | Antonin Houska <ah(at)cybertec(dot)at> |
Cc: | "pgsql-hackers(at)postgresql(dot)org" <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: PoC: Grouped base relation |
Date: | 2017-01-10 18:39:14 |
Message-ID: | CA+TgmoY=8UOHM-QPvfN59XHaPmx9SJrxLzkjcwcqKpg+1NJ2PA@mail.gmail.com |
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Lists: | pgsql-hackers |
On Mon, Jan 9, 2017 at 12:56 PM, Antonin Houska <ah(at)cybertec(dot)at> wrote:
> Attached is a draft patch that lets partial aggregation happen at base
> relation level. If the relations contain relatively small number of groups,
> the number of input rows of the aggregation at the query level can be reduced
> this way. Also, if append relation and postgres_fdw planning is enhanced
> accordingly, patch like this can let us aggregate individual tables on remote
> servers (e.g. shard nodes) and thus reduce the amount of rows subject to the
> final aggregation.
Very interesting. I don't have time to study this in detail right
now, but as a concept it seems worthwhile. I think the trick is
figuring out at which levels of the path tree it makes sense to
consider partial aggregation.
--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company
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