Subject: Re: Building multiple indexes concurrently
From: Hannu Krosing <hannu@2ndquadrant.com>
To: Greg Smith <greg@2ndquadrant.com>
Cc: Alvaro Herrera <alvherre@commandprompt.com>,
	Andres Freund <andres@anarazel.de>, pgsql-performance@postgresql.org,
	Rob Wultsch <wultsch@gmail.com>, Tom Lane <tgl@sss.pgh.pa.us>
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	<4BA12328.4080803@2ndquadrant.com>
	<201003172024.10538.andres@anarazel.de>
	<20100317202401.GC3902@alvh.no-ip.org>
	<4BA1403D.9030402@2ndquadrant.com>
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Date: Wed, 17 Mar 2010 23:18:47 +0200
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On Wed, 2010-03-17 at 16:49 -0400, Greg Smith wrote:
> Alvaro Herrera wrote:
> > Andres Freund escribió:
> >
> >   
> >> I find it way much easier to believe such issues exist on a tables in 
> >> constrast to indexes. The likelihood to get sequential accesses on an index is 
> >> small enough on a big table to make it unlikely to matter much.
> >>     
> >
> > Vacuum walks indexes sequentially, for one.
> >   
> 
> That and index-based range scans were the main two use-cases I was 
> concerned would be degraded by interleaving index builds, compared with 
> doing them in succession. 

I guess that tweaking file systems to allocate in bigger chunks help
here ? I know that xfs can be tuned in that regard, but how about other
common file systems like ext3 ?

- 
Hannu Krosing   http://www.2ndQuadrant.com
PostgreSQL Scalability and Availability 
   Services, Consulting and Training