Re: In which case PG_VERSION file updates ?

On Sunday, September 25, 2011 2:26:56 am Raghavendra wrote:
> Thanks Adrian Klaver,
>
> Provided link gives about the information of what PG_VERSION file, which am
> aware of:)
>
> In my observation, all the object related OID's, _fsm, _vm files under
> $PGDATA/base/database-oid/ directory will change as per the changes made to
> the database, whereas PG_VERSION file never changes. Because its the file
> tells on which version of Binary the Data directory is built upon.
>
> So, my question is, Is there any case, where PG_VERSION file updates with
> any of the utility process or
> PG_VERSION file never been touched by PG-Instance ?

From what I can see, PG_VERSION is written at database creation to document the
major version of the Postgres instance used to create the database. Since it
only holds the major version string (i.e. 9.0) it is not touched during minor
updates, for example 9.0.0 --> 9.0.1. Grepping the pg_upgrade code shows it
might touch PG_VERSION. A quick grep on the rest of the source code shows only
initdb writing out PG_VERSION, though it is checked by other code. This is by no
means an in depth look and it would take some one with more knowledge of
Postgres internals to give you a definitive answer. Might be worth a post on -
hackers.

>
> ---
> Regards,
> Raghavendra
> EnterpriseDB Corporation
> Blog: http://raghavt.blogspot.com/
>

--
Adrian Klaver
adrian(dot)klaver(at)gmail(dot)com