Re: Vacuum analyze in 7.1.1
От | David Wall |
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Тема | Re: Vacuum analyze in 7.1.1 |
Дата | |
Msg-id | 006501c0f45b$eca1c580$5a2b7ad8@expertrade.com обсуждение исходный текст |
Ответ на | Vacuum analyze in 7.1.1 ("David Wall" <d.wall@computer.org>) |
Ответы |
Re: Vacuum analyze in 7.1.1
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Список | pgsql-general |
> AFAIK that's always been true, but some of the documentation has been > confused about it :-(. If you can find anything in the 7.1 docs that > sounds like VACUUM ANALYZE doesn't include VACUUM, please point it out. Thanks. The documentation doesn't say that VACUUM ANALYZE doesn't do a regular VACUUM as well, but it does say: "VACUUM serves two purposes in Postgres as both a means to reclaim storage and also a means to collect information for the optimizer." So, I know it does two things. It then says: "VACUUM ANALYZE collects statistics representing the dispersion of the data in each column. This information is valuable when several query execution paths are possible." This is also clear to me, but it left open the possibility that this is ALL that ANALYZE does, and does not clean out records and update the stats as VACUUM does. The docs say that VACUUM: "VACUUM opens every table in the database, cleans out records from rolled back transactions, and updates statistics in the system catalogs. The statistics maintained include the number of tuples and number of pages stored in all tables." Isn't also true that VACUUM cleans out deleted and updated rows for committed transactions? And for those who use large objects, I understand that vacuum now cleans those up when they are deleted as well (no need for vacuumlo anymore). Perhaps it would be clear to just add words to that affect, and to mention that VACUUM ANALYZE does a VACUUM plus it collects statistics... David
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