From: Andres Freund <andres@anarazel.de>
To: pgsql-performance@lists.postgresql.org,Tom Lane <tgl@sss.pgh.pa.us>
To: Zakhar Shapurau <zak@zvs.no>
Cc: pgsql-performance@postgresql.org
Subject: Re: Using GROUPING SETS with more than one set disables predicate pushdown?
Date: Tue, 21 Nov 2017 10:16:56 -0800
Message-ID: <64AFD0D3-9782-4D3B-9366-5B9EEA4DCB0F@anarazel.de> (raw)
In-Reply-To: <1703.1511275766@sss.pgh.pa.us>
References: <1511262257.3219920.1179611992.260EC9D9@webmail.messagingengine.com>
<1703.1511275766@sss.pgh.pa.us>
On November 21, 2017 6:49:26 AM PST, Tom Lane <tgl@sss.pgh.pa.us> wrote:
>Zakhar Shapurau <zak@zvs.no> writes:
>
>Presumably, we could examine the grouping sets to identify column(s)
>present in all sets, and then allow the optimization for clauses that
>reference only such columns. Or maybe I'm misreading the comment
>(but then it needs clarification).
By memory that sounds about right. IIRC we'd some slightly more elaborate logic when GS were introduced, but had to take it out as buggy, and it was too late in the development cycle to come up with something better.
Andres
Andres
--
Sent from my Android device with K-9 Mail. Please excuse my brevity.
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To: pgsql-performance@postgresql.org
Cc: andres@anarazel.de, tgl@sss.pgh.pa.us, zak@zvs.no
Subject: Re: Using GROUPING SETS with more than one set disables predicate pushdown?
In-Reply-To: <64AFD0D3-9782-4D3B-9366-5B9EEA4DCB0F@anarazel.de>
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