Re: Name for new VACUUM
От | Tom Lane |
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Тема | Re: Name for new VACUUM |
Дата | |
Msg-id | 20228.996848757@sss.pgh.pa.us обсуждение исходный текст |
Ответ на | Re: Name for new VACUUM (Bruce Momjian <pgman@candle.pha.pa.us>) |
Ответы |
Re: Re: Name for new VACUUM
Re: Name for new VACUUM |
Список | pgsql-hackers |
mlw <markw@mohawksoft.com> writes: > ... people looked at me like I had two heads when I told them about > "vacuum." It wasn't obvious to them what it did. I won't dispute that, but changing a command name that's been around for ten or fifteen years strikes me as a recipe for more confusion, not less. > However, saying that VACUUM NOLOCK and VACUUM LOCK do "more-or-less > the same thing" really isn't so. Think about it, the VACUUM LOCK, > practically rebuilds a tables representation, It does no such thing. The only difference is that it's willing to move a few tuples around if it can thereby free up (and truncate) whole pages at the end of the table. (In a live system you'd better hope it's only a few tuples, anyway ;-) ... or you'll be waiting a long time.) It doesn't even do a complete defrag; it stops moving tuples as soon as it finds that it won't be able to truncate the table any further. So there's *not* that much difference. > VACUUM DEFRAG? > VACUUM COMPRESS? While these look kinda ugly to me, I can find no stronger objection than that. (Well, maybe I could complain that these overstate what old-style vacuum actually does, but that's even weaker.) What do other people think? regards, tom lane
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