Re: PostgreSQL Arrays and Performance - Mailing list pgsql-general

From Jim C. Nasby
Subject Re: PostgreSQL Arrays and Performance
Date
Msg-id 20060110203419.GF3902@pervasive.com
Whole thread Raw
In response to Re: PostgreSQL Arrays and Performance  (Marc Philipp <mail@marcphilipp.de>)
List pgsql-general
On Sun, Jan 08, 2006 at 10:22:22AM +0100, Marc Philipp wrote:
> > This sounds like it has more to do with inadequate freespace map
> > settings than use of arrays. Every update creates a dead tuple, and
> > if
> > it is large (because the array is large) and leaked (because you have
> > no
> > room in your freespace map), that would explain a rapidly increasing
> > database size.
>
> Can you tell me more about free-space map settings? What exactly is the
> free-space map? The information in the documentation is not very
> helpful. How can dead tuples leak?

http://www.pervasive-postgres.com/lp/newsletters/2005/Insights_opensource_Nov.asp#3
is an article I wrote that might clear things up.
http://www.pervasive-postgres.com/lp/newsletters/2005/Insights_opensource_Dec.asp#2
might also be an interesting read, though it's just about MVCC in
general.
--
Jim C. Nasby, Sr. Engineering Consultant      jnasby@pervasive.com
Pervasive Software      http://pervasive.com    work: 512-231-6117
vcard: http://jim.nasby.net/pervasive.vcf       cell: 512-569-9461

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