Re: strange performance regression between 7.4 and 8.1

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Alex Deucher wrote:
> Hello,
> 
> I have noticed a strange performance regression and I'm at a loss as
> to what's happening.  We have a fairly large database (~16 GB).  The
> original postgres 7.4 was running on a sun v880 with 4 CPUs and 8 GB
> of ram running Solaris on local scsi discs.  The new server is a sun
> Opteron box with 4 cores, 8 GB of ram running postgres 8.1.4 on Linux
> (AMD64) on a 4 Gbps FC SAN volume.  When we created the new database
> it was created from scratch rather than copying over the old one,
> however the table structure is almost identical (UTF8 on the new one
> vs. C on the old). The problem is queries are ~10x slower on the new
> hardware.  I read several places that the SAN might be to blame, but
> testing with bonnie and dd indicates that the SAN is actually almost
> twice as fast as the scsi discs in the old sun server.  I've tried
> adjusting just about every option in the postgres config file, but
> performance remains the same.  Any ideas?

Vacuum? Analayze? default_statistics_target? How many shared_buffers?
effective_cache_size? work_mem?

Sincerely,

Joshua D. Drake


> 
> Thanks,
> 
> Alex
> 
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