Horton

Re: Help with count(*)

Hannu Krosing <hannu@tm.ee>

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From: Hannu Krosing <hannu@tm.ee>
To: Christopher Browne <cbbrowne@acm.org>
Cc: pgsql-performance@postgresql.org
Date: 2003-11-14T17:43:27Z
Lists: pgsql-hackers, pgsql-performance 
Christopher Browne kirjutas R, 14.11.2003 kell 16:13:
> Martha Stewart called it a Good Thing when mallah@trade-india.com (Rajesh Kumar Mallah) wrote:
> > INFO:  "profiles": found 0 removable, 369195 nonremovable row versions in 43423 pages
> > DETAIL:  246130 dead row versions cannot be removed yet.
> > Nonremovable row versions range from 136 to 2036 bytes long.
> 
> It seems as though you have a transaction open that is holding onto a
> whole lot of old rows.
> 
> I have seen this happen somewhat-invisibly when a JDBC connection
> manager opens transactions for each connection, and then no processing
> happens to use those connections for a long time.  The open
> transactions prevent vacuums from doing any good...

Can't the backend be made to delay the "real" start of transaction until
the first query gets executed ?

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Hannu