pg.ddx.io pgsql-hackers@postgresql.org mailing list archive help / color / mirror / Atom feed From: Tom Lane <tgl@sss.pgh.pa.us>
To: David Rowley <david.rowley@2ndquadrant.com>
Cc: Jesper Pedersen <jesper.pedersen@redhat.com>
Cc: Andres Freund <andres@anarazel.de>
Cc: Robert Haas <robertmhaas@gmail.com>
Cc: PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Subject: Re: POC: converting Lists into arrays
Date: Mon, 22 Jul 2019 00:54:00 -0400
Message-ID: <29776.1563771240@sss.pgh.pa.us> (raw )
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David Rowley <david.rowley@2ndquadrant.com> writes:
> On Mon, 22 Jul 2019 at 16:37, Tom Lane <tgl@sss.pgh.pa.us> wrote:
>> Interesting. I wonder if bms_next_member() could be made any quicker?
> I had a quick look earlier and the only thing I saw was maybe to do
> the first loop differently from subsequent ones. The "w &= mask;"
> does nothing useful once we're past the first bitmapword that the loop
> touches.
Good thought, but it would only help when we're actually iterating to
later words, which happens just 1 out of 64 times in the fully-
populated-bitmap case.
Still, I think it might be worth pursuing to make the sparse-bitmap
case faster.
regards, tom lane
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To: pgsql-hackers@postgresql.org
Cc: tgl@sss.pgh.pa.us, david.rowley@2ndquadrant.com, jesper.pedersen@redhat.com, andres@anarazel.de, robertmhaas@gmail.com, pgsql-hackers@lists.postgresql.org
Subject: Re: POC: converting Lists into arrays
In-Reply-To: <29776.1563771240@sss.pgh.pa.us>
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