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Re: Vacuum-full very slow
- From: Alvaro Herrera <alvherre(at)commandprompt(dot)com>
- To: Listmail <lists(at)peufeu(dot)com>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Steve Crawford <scrawford(at)pinpointresearch(dot)com>, pgsql-general(at)postgresql(dot)org
- Subject: Re: Vacuum-full very slow
- Date: Fri, 27 Apr 2007 09:18:08 -0400
Martijn van Oosterhout wrote: > 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. Hmm, no, CLUSTER doesn't scan the table linearly; it uses an indexscan, so it also needs seek/read/seek/read/write. -- Alvaro Herrera http://www.CommandPrompt.com/ The PostgreSQL Company - Command Prompt, Inc.
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- Vacuum-full very slow
- From: Steve Crawford
- Re: Vacuum-full very slow
- From: Alvaro Herrera
- Re: Vacuum-full very slow
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- Re: Vacuum-full very slow
- From: Steve Crawford
- Re: Vacuum-full very slow
- From: Alvaro Herrera
- Re: Vacuum-full very slow
- From: Tom Lane
- Re: Vacuum-full very slow
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- Re: Vacuum-full very slow
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