From: Alvaro Herrera <alvherre@2ndquadrant.com>
To: Andres Freund <andres@anarazel.de>
Cc: Amit Kapila <amit.kapila16@gmail.com>
Cc: pgsql-hackers <pgsql-hackers@postgresql.org>
Subject: Re: Speed up Clog Access by increasing CLOG buffers
Date: Mon, 7 Sep 2015 15:56:39 -0300
Message-ID: <20150907185639.GQ2912@alvherre.pgsql> (raw)
In-Reply-To: <20150907164908.GB5084@alap3.anarazel.de>
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Andres Freund wrote:
> On 2015-09-07 10:34:10 -0300, Alvaro Herrera wrote:
> > I wonder if it would make sense to explore an idea that has been floated
> > for years now -- to have pg_clog pages be allocated as part of shared
> > buffers rather than have their own separate pool. That way, no separate
> > hardcoded allocation limit is needed. It's probably pretty tricky to
> > implement, though :-(
>
> I still think that'd be a good plan, especially as it'd also let us use
> a lot of related infrastructure. I doubt we could just use the standard
> cache replacement mechanism though - it's not particularly efficient
> either... I also have my doubts that a hash table lookup at every clog
> lookup is going to be ok performancewise.
Yeah. I guess we'd have to mark buffers as unusable for regular pages
("somehow"), and have a separate lookup mechanism. As I said, it is
likely to be tricky.
--
Álvaro Herrera http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
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To: pgsql-hackers@postgresql.org
Cc: alvherre@2ndquadrant.com, andres@anarazel.de, amit.kapila16@gmail.com
Subject: Re: Speed up Clog Access by increasing CLOG buffers
In-Reply-To: <20150907185639.GQ2912@alvherre.pgsql>
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