Re: pgbench --unlogged-tables

On Fri, Jul 22, 2011 at 10:15:08PM -0400, Greg Smith wrote:
> On 07/22/2011 08:15 PM, David Fetter wrote:
> >Do you have any theories as to how indexing on SSD speeds things
> >up?  IIRC you found only marginal benefit in putting WALs there.
> >Are there cases that SSD helps more than others when it comes to
> >indexing?
> 
> Yes, I've found a variety of workloads where using a SSD turns out
> to be slower than the old-school array of drives with a
> battery-backed write cache.  Tiny commits are slower, sequential
> writes can easily be slower, and if there isn't a random I/O
> component to the job the SSD won't get any way to make up for that.

So you're saying this is more of a flash thing than an SSD thing?  I
haven't heard of systems with PCM having this limitation.

Cheers,
David.
-- 
David Fetter <david@fetter.org> http://fetter.org/
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