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help / color / mirror / Atom feedFrom: Alvaro Herrera <alvherre@2ndquadrant.com>
To: Antonin Houska <ah@cybertec.at>
Cc: Michael Paquier <michael@paquier.xyz>
Cc: Thomas Munro <thomas.munro@gmail.com>
Cc: Robert Haas <robertmhaas@gmail.com>
Cc: pgsql-hackers@postgresql.org <pgsql-hackers@postgresql.org>
Subject: Re: Attempt to consolidate reading of XLOG page
Date: Fri, 22 Nov 2019 10:35:51 -0300
Message-ID: <20191122133551.GA4216@alvherre.pgsql> (raw)
In-Reply-To: <454.1574407712@antos>
On 2019-Nov-22, Antonin Houska wrote:
> I thought that in [1] you try discourage me from using pg_pread(), but now it
> seems to be the opposite. Ideally I'd like to see no overhead added by my
> patch at all, but the code simplicity should matter too.
FWIW I think the new code is buggy because it doesn't seem to be setting
ws_off, so I suppose the optimization in ReadPageInternal to skip
reading the page when it's already the page we have is not hit, except
for the first page in the segment. I didn't verify this, just my
impression while reading the code.
--
Álvaro Herrera https://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
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To: pgsql-hackers@postgresql.org
Cc: alvherre@2ndquadrant.com, ah@cybertec.at, michael@paquier.xyz, thomas.munro@gmail.com, robertmhaas@gmail.com
Subject: Re: Attempt to consolidate reading of XLOG page
In-Reply-To: <20191122133551.GA4216@alvherre.pgsql>
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