Re: reindex/vacuum locking/performance?

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От Matt Clark
Тема Re: reindex/vacuum locking/performance?
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Msg-id LFEIJBEOKGPDHCEMDGNFAEPOCFAA.matt@ymogen.net
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Ответ на Re: reindex/vacuum locking/performance?  (Tom Lane <tgl@sss.pgh.pa.us>)
Список pgsql-performance
> Mainly 'cause it doesn't know where the dead tuples are till it's
> looked.

At this point I feel very stupid...

> Also, VACUUM is the data collector for the free space map,
> and so it is also charged with finding out how much free space exists
> on every page.

Ah, now I just feel enlightened!  That makes perfect sense.  I think I had
been conflating free pages with free space, without understanding what the
difference was.  Of course I still don't really understand, but at least I
now _know_ I don't.

Many thanks

Matt


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