Re: Why age (datfrozenxid) in postgres becomes 1073742202 not zero after each vacuum of database. - Mailing list pgsql-performance

From Robert Haas
Subject Re: Why age (datfrozenxid) in postgres becomes 1073742202 not zero after each vacuum of database.
Date
Msg-id 603c8f070911131305t1fc446fcw13df71b67da9093@mail.gmail.com
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In response to Why age (datfrozenxid) in postgres becomes 1073742202 not zero after each vacuum of database.  ("Brahma Prakash Tiwari" <brahma.tiwari@inventum.cc>)
List pgsql-performance
[ removing -jobs from cc list as it is not appropriate for this posting ]

On Thu, Nov 12, 2009 at 3:18 AM, Brahma Prakash Tiwari
<brahma.tiwari@inventum.cc> wrote:
> Hi all
>
> Why age (datfrozenxid) in postgres becomes 1073742202 not zero after vacuum
> of database.
>
> Thanks in advance

I think you're misunderstanding the meaning of the column.  As the
fine manual explains:

"Similarly, the datfrozenxid column of a database's pg_database row is
a lower bound on the normal XIDs appearing in that database — it is
just the minimum of the per-table relfrozenxid values within the
database."

http://www.postgresql.org/docs/current/static/routine-vacuuming.html

...Robert

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