| From: | Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> |
|---|---|
| To: | Hiroshi Inoue <Inoue(at)tpf(dot)co(dot)jp> |
| Cc: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: [HACKERS] Re: vacuum timings |
| Date: | 2000-01-22 17:33:29 |
| Message-ID: | 200001221733.MAA21558@candle.pha.pa.us |
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| Lists: | pgsql-hackers |
> > Quite a few people have reported finding the opposite in practice.
> > You should probably try vacuuming after deleting or updating some
> > fraction of the rows, rather than just the all or none cases.
> >
>
> Vacuum after delelting all rows isn't a worst case.
> There's no moving in that case and vacuum doesn't need to call
> index_insert() corresponding to the moving of heap tuples.
>
> Vacuum after deleting half of rows may be one of the worst case.
> In this case,index_delete() is called as many times as 'delete all'
> case and expensive index_insert() is called for moved_in tuples.
I will test that.
--
Bruce Momjian | http://www.op.net/~candle
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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