Re: Help with count(*) - Mailing list pgsql-performance

From Christopher Browne
Subject Re: Help with count(*)
Date
Msg-id m3ad6zkpgj.fsf@wolfe.cbbrowne.com
Whole thread Raw
In response to Help with count(*)  (Rajesh Kumar Mallah <mallah@trade-india.com>)
Responses Re: Help with count(*)  (Hannu Krosing <hannu@tm.ee>)
List pgsql-performance
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...
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