Re: Vacuum DB in Postgres Vs similar concept in other RDBMS
От | Tom Lane |
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Тема | Re: Vacuum DB in Postgres Vs similar concept in other RDBMS |
Дата | |
Msg-id | 28353.1179983512@sss.pgh.pa.us обсуждение исходный текст |
Ответ на | Re: Vacuum DB in Postgres Vs similar concept in other RDBMS (Ron Johnson <ron.l.johnson@cox.net>) |
Ответы |
Re: Vacuum DB in Postgres Vs similar concept in other RDBMS
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Список | pgsql-general |
Ron Johnson <ron.l.johnson@cox.net> writes: >> harpreet.dhaliwal01@gmail.com ("Harpreet Dhaliwal") writes: >>> I was just wondering if Vacuum Db in postgresql is somehow superior >>> to the ones that we have in other RDBMS. > So it's not "near-zero cost", it's "deferred cost". Exactly. VACUUM sucks (ahem) in all ways but one: it pushes the maintenance costs associated with MVCC out of the foreground query code paths and into an asynchronous cleanup task. AFAIK we are the only DBMS that does it that way. Personally I believe it's a fundamentally superior approach --- because when you are under peak load you can defer the cleanup work --- but you do need to pay attention to make sure that the async cleanup isn't postponed too long. We're still fooling around with autovacuum and related tuning issues to make it work painlessly... regards, tom lane
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