| 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: | 2009-06-26 20:30:34 |
| Message-ID: | 28355.1246048234@sss.pgh.pa.us |
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| Lists: | pgsql-hackers |
"Kevin Grittner" <Kevin(dot)Grittner(at)wicourts(dot)gov> writes:
> Regarding the fact that even with the xlog files pre-populated, the
> smaller set of xlog files is faster: I'm only guessing, but I suspect
> the battery backed RAID controller is what's defeating conventional
> wisdom here. By writing to the same, relatively small, set of xlog
> files repeatedly, some of the actual disk writes probably evaporate in
> the BBU cache.
Yeah, sounds plausible. How big is your BBU cache?
regards, tom lane
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