Re: Automatic free space map filling
От | Hannu Krosing |
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Тема | Re: Automatic free space map filling |
Дата | |
Msg-id | 1146656049.3824.28.camel@localhost.localdomain обсуждение исходный текст |
Ответ на | Re: Automatic free space map filling (Tom Lane <tgl@sss.pgh.pa.us>) |
Ответы |
Re: Automatic free space map filling
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Список | pgsql-hackers |
Ühel kenal päeval, R, 2006-03-03 kell 11:37, kirjutas Tom Lane: > Alvaro Herrera <alvherre@commandprompt.com> writes: > > So for you it would certainly help a lot to be able to vacuum the first > > X pages of the big table, stop, release locks, create new transaction, > > continue with the next X pages, lather, rinse, repeat. > > > This is perfectly doable, it only needs enough motivation from a > > knowledgeable person. > > Bruce and I were discussing this the other day; it'd be pretty easy to > make plain VACUUM start a fresh transaction immediately after it > finishes a scan heap/clean indexes/clean heap cycle. Do you mean the full (scan heap/clean indexes/clean heap) cycle or some smaller cycles inside each step ? If you mean the full cycle, then it is probably not worth it, as even a single 'clean index' pass can take hours on larger tables. > The infrastructure > for this (in particular, session-level locks that won't be lost by > closing the xact) is all there. You'd have to figure out how often to > start a new xact ... every cycle is probably too often, at least for > smaller maintenance_work_mem settings ... but it'd not be hard or > involve any strange changes in system semantics. ----------- Hannu
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