Re: Spread checkpoint sync

From: Greg Smith <greg(at)2ndquadrant(dot)com>
To: Kevin Grittner <Kevin(dot)Grittner(at)wicourts(dot)gov>
Cc: cedric(dot)villemain(dot)debian(at)gmail(dot)com, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Spread checkpoint sync
Date: 2011-02-07 22:06:46
Message-ID: 4D506CF6.6080407@2ndquadrant.com
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Kevin Grittner wrote:
> There are occasional posts from those wondering why their read-only
> queries are so slow after a bulk load, and why they are doing heavy
> writes. (I remember when I posted about that, as a relative newbie,
> and I know I've seen others.)
>

Sure; I created http://wiki.postgresql.org/wiki/Hint_Bits a while back
specifically to have a resource to explain that mystery to offer
people. But there's a difference between having a performance issue
that people don't understand, and having a real bottleneck you can't get
rid of. My experience is that people who have hint bit issues run into
them as a minor side-effect of a larger vacuum issue, and that if you
get that under control they're only a minor detail in comparison. Makes
it hard to get too excited about optimizing them.

--
Greg Smith 2ndQuadrant US greg(at)2ndQuadrant(dot)com Baltimore, MD
PostgreSQL Training, Services, and 24x7 Support www.2ndQuadrant.us
"PostgreSQL 9.0 High Performance": http://www.2ndQuadrant.com/books

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