Re: A question about Vacuum analyze
От | Emi Lu |
---|---|
Тема | Re: A question about Vacuum analyze |
Дата | |
Msg-id | 43F60292.2050605@encs.concordia.ca обсуждение исходный текст |
Ответ на | Re: A question about Vacuum analyze (Ragnar <gnari@hive.is>) |
Ответы |
Re: A question about Vacuum analyze
Re: A question about Vacuum analyze |
Список | pgsql-general |
>>>>In another way, whenever we "delete/truncate and then insert" data into >>>>a table, it is better to "vacuum anaylze"? >>>> >>>> >>>> >>>> >>>You shouldn't need a VACUUM if you haven't yet done any updates or >>>deletes since the TRUNCATE. An ANALYZE seems like a good idea, though. >>>(You could get away without ANALYZE if the new data has essentially the >>>same statistics as the old, but if you're making only minor changes, why >>>are you using this technique at all ...) >>> >>> >>> >>> >>After truncate table A, around 60,000 will be inserted. Then a >>comparision will be done between table A and table B. After that, table >>B will be updated according to the comparision result. Records inserted >>into table A is increasing everyday. >> >>So, your suggestion is that after the population of table A, the query >>planner should be able to find the most efficient query plan because we >>do truncate but not delete, and we do not need to do vacuum analyze at >>all, right? >> >> > >no. the suggestion was that a VACUUM is not needed, but >that an ANALYZE might be. > > Thank you gnari for your answer. But I am a bit confused about not running vacuum but only "analyze". Can I seperate thesetwo operations? I guess "vacuum analyze" do both vacuum and analyze. Or "EXPLAIN ANALYZE" can do it for me? Emi
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