| From: | Martijn van Oosterhout <kleptog(at)svana(dot)org> |
|---|---|
| To: | Listmail <lists(at)peufeu(dot)com> |
| Cc: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Alvaro Herrera <alvherre(at)commandprompt(dot)com>, Steve Crawford <scrawford(at)pinpointresearch(dot)com>, pgsql-general(at)postgresql(dot)org |
| Subject: | Re: Vacuum-full very slow |
| Date: | 2007-04-27 11:47:46 |
| Message-ID: | 20070427114746.GC32406@svana.org |
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| Lists: | pgsql-general pgsql-hackers |
On Thu, Apr 26, 2007 at 12:13:13AM +0200, Listmail wrote:
> VACUUM FULL is slow because it plays with the indexes...
> CLUSTER is slow because it has to order the rows...
And:
VACUUM FULL has to seek/read/write all over the disk to get it's job
done.
CLUSTER can scan through the table linearly a few times and write out
the result.
Now it's true that sorting large files involves overflowing to disk,
but that path has been pretty well optimised.
As the ratio between read time and seek time gets worse, I expect
CLUSTER to keep pulling ahead.
Have a nice day,
--
Martijn van Oosterhout <kleptog(at)svana(dot)org> http://svana.org/kleptog/
> From each according to his ability. To each according to his ability to litigate.
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