Re: Postgres Benchmark Results - Mailing list pgsql-performance

From Guido Neitzer
Subject Re: Postgres Benchmark Results
Date
Msg-id 37E3AB9B-77D7-4757-A379-29BE25F63533@event-s.net
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In response to Re: Postgres Benchmark Results  ("Jim C. Nasby" <decibel@decibel.org>)
Responses Re: Postgres Benchmark Results  (Greg Smith <gsmith@gregsmith.com>)
List pgsql-performance
Am 21.05.2007 um 15:01 schrieb Jim C. Nasby:

> I'd be willing to bet money that the drive is lying about commits/
> fsync.
> Each transaction committed essentially requires one revolution of the
> drive with pg_xlog on it, so a 15kRPM drive limits you to 250TPS.

Yes, that right, but if a lot of the transactions are selects, there
is no entry in the x_log for them and most of the stuff can come from
the cache - read from memory which is blazing fast compared to any
disk ... And this was a pg_bench test - I don't know what the
benchmark really does but if I remember correctly it is mostly reading.

cug



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