| From: | Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> |
|---|---|
| To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Cc: | Peter Eisentraut <peter_e(at)gmx(dot)net>, Jean-Christophe Boggio <cat(at)thefreecat(dot)org>, PostgreSQL General <pgsql-general(at)postgresql(dot)org> |
| Subject: | Re: vacuum analyze again... |
| Date: | 2001-02-20 18:51:26 |
| Message-ID: | 200102201851.NAA12656@candle.pha.pa.us |
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| Lists: | pgsql-general |
> To get a partial VACUUM ANALYZE that was actually usefully faster than
> the current code, I think you'd have to read just a few percent of the
> blocks, which means much less than a few percent of the rows ... unless
> maybe you picked selected blocks but then used all the rows in those
> blocks ... but is that a random sample? It's debatable.
>
> I find it hard to believe that VAC ANALYZE is all that much slower than
> plain VACUUM anyway; fixing the indexes is the slowest part of VACUUM in
> my experience. It would be useful to know exactly what the columns are
> in a table where VAC ANALYZE is considered unusably slow.
VACUUM ANALYZE does a huge number of adt/ function calls. It must be
those calls that make ANALYZE slower. People report ANALYZE is
certainly slower, and that is the only difference.
--
Bruce Momjian | http://candle.pha.pa.us
pgman(at)candle(dot)pha(dot)pa(dot)us | (610) 853-3000
+ If your life is a hard drive, | 830 Blythe Avenue
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