| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | "Kevin Grittner" <Kevin(dot)Grittner(at)wicourts(dot)gov> |
| Cc: | "Simon Riggs" <simon(at)2ndquadrant(dot)com>, "Andrew Dunstan" <andrew(at)dunslane(dot)net>, "Heikki Linnakangas" <heikki(dot)linnakangas(at)enterprisedb(dot)com>, "Robert Haas" <robertmhaas(at)gmail(dot)com>, "Greg Smith" <gsmith(at)gregsmith(dot)com>, "Stefan Kaltenbrunner" <stefan(at)kaltenbrunner(dot)cc>, "PostgreSQL-development" <pgsql-hackers(at)postgresql(dot)org>, "Alan Li" <ali(at)truviso(dot)com> |
| Subject: | Re: 8.4 open item: copy performance regression? |
| Date: | 2009-06-22 23:01:42 |
| Message-ID: | 3147.1245711702@sss.pgh.pa.us |
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"Kevin Grittner" <Kevin(dot)Grittner(at)wicourts(dot)gov> writes:
> The checkpoint_segments seems dramatic enough to be real. I wonder if
> the test is short enough that it never got around to re-using any of
> them, so it was doing extra writes for the initial creation during the
> test?
That's exactly what I was about to suggest. Are you starting each run
from a fresh initdb? If so, try running the load long enough that the
number of WAL files stabilizes (should happen at 2x checkpoint_segments)
and then start the test measurement.
regards, tom lane
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