Re: Vacuum Full - stops responding(?)
От | Alvaro Herrera |
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Тема | Re: Vacuum Full - stops responding(?) |
Дата | |
Msg-id | 20091021030340.GC29592@alvh.no-ip.org обсуждение исходный текст |
Ответ на | Re: Vacuum Full - stops responding(?) (Greg Stark <gsstark@mit.edu>) |
Ответы |
Re: Vacuum Full - stops responding(?)
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Список | pgsql-admin |
Greg Stark escribió: > On Mon, Oct 19, 2009 at 8:56 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote: > > Greg Stark <gsstark@mit.edu> writes: > >> The run-time of CLUSTER doesn't vary very much based on whether the > >> data is already in index order or not. The number of passes only grows > >> like log(n) of the size of your data and if you set > >> maintenance_work_mem large enough (somewhere around 100MB-1GB) the > >> constants are small enough that you're unlikely to even outgrow a > >> single pass (plus a final merge though) > > > > Uh ... what? It's not based on the sort code, unless someone rewrote it > > since I looked last. It's an index scan and will definitely depend on > > the index ordering. > > Er, uh, of course. I wonder what I was thinking. Your patched version of course. -- Alvaro Herrera http://www.CommandPrompt.com/ The PostgreSQL Company - Command Prompt, Inc.
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