Re: Question to transaction ID wraparound

On Fri, Feb 27, 2009 at 4:42 AM, Lentes, Bernd
<bernd(dot)lentes(at)helmholtz-muenchen(dot)de> wrote:
>
>
> Scott Marlowe wrote:
>> -----Ursprüngliche Nachricht-----
>> Von: Scott Marlowe [mailto:scott(dot)marlowe(at)gmail(dot)com]
>> Gesendet: Freitag, 27. Februar 2009 11:04
>> An: Lentes, Bernd
>> Cc: pgsql-admin(at)postgresql(dot)org
>> Betreff: Re: [ADMIN] Question to transaction ID wraparound
>>
>> On Wed, Feb 25, 2009 at 3:05 AM, Lentes, Bernd
>> <bernd(dot)lentes(at)helmholtz-muenchen(dot)de> wrote:
>> > Hello ML,
>> >
>> > I'm very new to Postgres.
>> > In the log, i got messages concerning transaction ID wraparound.
>> > I red the documentation and made a vaccum on that database.
>> > In the documentation i also found the hint to look in the database
>> > with "SELECT datname, age(datfrozenxid) FROM pg_database;",
>> which i did.
>> > I did the command several times in a few seconds, and this
>> number is
>> > growing very quickly, although i'm not expecting
>> transactions in the database.
>>
>> Please note that nearly EVERYTHING that happens in postgres
>> is a transaction.  if you type a single command, boom, it's a
>> transaction.
>> You actually get fewer transaction events if you enclose a
>> bunch of stuff in begin; commit; pairs than if you run single
>> commands.
>>
> Scott, why does the number increase ?
> If it says how many transactions are still possible, the number should decrease, not increase.

What I wrote was about the number you saw from the log entries. That
tells you how many transactions you have left before wraparound would
happen.

Read up on what the age() stuff means here:

http://www.postgresql.org/docs/8.3/static/routine-vacuuming.html