Message-ID: <4C619A4F.7080306@2ndquadrant.com>
Date: Tue, 10 Aug 2010 14:28:31 -0400
From: Greg Smith <greg@2ndquadrant.com>
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To: Brad Nicholson <bnichols@ca.afilias.info>
CC: Scott Carey <scott@richrelevance.com>, Michael March <mmarch@gmail.com>,
	"pgsql-performance@postgresql.org" <pgsql-performance@postgresql.org>
Subject: Re: Completely un-tuned Postgresql benchmark results: SSD
	vs desktop HDD
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Brad Nicholson wrote:
> What about putting indexes on them?  If the drive fails and drops 
> writes on those, they could be rebuilt - assuming your system can 
> function without the index(es) temporarily.

Dumping indexes on SSD is one of the better uses for them, presuming you 
can survive what is likely to be an outage from a "can the site handle 
full load?" perspective while they rebuild after a crash.  As I'm sure 
Brad is painfully aware of already, index rebuilding in PostgreSQL can 
take a while.  To spin my broken record here again, the main thing to 
note when you consider that--relocate indexes onto SSD--is that the ones 
you are most concerned about the performance of were likely to be 
already sitting in RAM anyway, meaning the SSD speedup doesn't help 
reads much.  So the giant performance boost just isn't there in that case.

-- 
Greg Smith  2ndQuadrant US  Baltimore, MD
PostgreSQL Training, Services and Support
greg@2ndQuadrant.com   www.2ndQuadrant.us