Re: LDC - Load Distributed Checkpoints with PG8.3b2 on Solaris

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От Alvaro Herrera
Тема Re: LDC - Load Distributed Checkpoints with PG8.3b2 on Solaris
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Msg-id 20071119135838.GC13505@alvh.no-ip.org
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Ответ на Re: LDC - Load Distributed Checkpoints with PG8.3b2 on Solaris  (Gregory Stark <stark@enterprisedb.com>)
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Gregory Stark wrote:
> "Heikki Linnakangas" <heikki@enterprisedb.com> writes:
> 
> > Tom Lane wrote:
> >> Looking at the autovacuum log output, 
> >>
> >>> 2007-11-13 09:21:19.830 PST 9458  LOG:  automatic vacuum of table
> >>> "specdb.public.txn_log_table": index scans: 1
> >>>         pages: 11 removed, 105 remain
> >>>         tuples: 3147 removed, 40 remain
> >>>         system usage: CPU 0.11s/0.09u sec elapsed 6.02 sec
> >>
> >> it seems like a serious omission that this gives you no hint how many
> >> pages were scanned.
> >
> > Isn't it pages removed + remain? 116 in this case.
> 
> How do 40 tuples take 105 pages?

The first 65 pages could be empty.

-- 
Alvaro Herrera                               http://www.PlanetPostgreSQL.org/
Bob [Floyd] used to say that he was planning to get a Ph.D. by the "green
stamp method," namely by saving envelopes addressed to him as 'Dr. Floyd'.
After collecting 500 such letters, he mused, a university somewhere in
Arizona would probably grant him a degree.              (Don Knuth)


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