Re: simple question
От | Rick Gigger |
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Тема | Re: simple question |
Дата | |
Msg-id | 005701c3aa19$31330f40$0700a8c0@trogdor обсуждение исходный текст |
Ответ на | Perfomance difference between 7.2 and 7.3 (Paulo Jan <admin@digital.ddnet.es>) |
Ответы |
Re: simple question
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Список | pgsql-general |
> > Is this correct? > > > > vacuum by itself just cleans out the old extraneous tuples so that they > > aren't in the way anymore > > Actually it puts the free space in each page on a list (the free space > map) so it can be reused for new tuples without having to allocate > fresh pages. It finds free space by looking for tuples that can't be > seen any more by any transaction. > > > vacuum analyze rebuilds indexes. If you add an index to a table it won't be > > used until you vacuum analyze it > > It doesn't rebuild indexes--REINDEX does that. ANALYZE measures the > size and statistics of the data in the table, so the planner can do a > good job. Is REINDEX something that needs to be done on a periodic basis? > > vacuum full actually compresses the table on disk by reclaiming the space > > from the old tuples after they have been removed. > > It moves tuples around and frees up pages at the end of the table, > thus compacting it. > > So you're mostly wrong on all three. :) > > -Doug > Thanks! Rick
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