Re: change location of postmaster.pid file?

Hi. Thanks for the quick and definitive answers to my questions.
The information you provided will save me from wasting time and
energy trying to see how far I could get otherwise. Thanks very much.

Janet

Tom Lane wrote:
> Janet Jacobsen <jsjacobsen(at)lbl(dot)gov> writes:
>
>> Is it possible to create a database cluster on a machine that
>> has write access to the shared file system, shut down the
>> Postgres server on that machine, and then start up the
>> Postgres server on the machine that cannot write to the
>> shared file system, and thereafter, *only query* the database.
>>
>
> No. The pid file is only the first and smallest problem you'd run into
> with a read-only database filesystem.
>
> regards, tom lane
>
>
> On Fri, Jul 10, 2009 at 11:17 PM, Janet Jacobsen<jsjacobsen(at)lbl(dot)gov> wrote:
>
>> > Is it possible to create a database cluster on a machine that
>> > has write access to the shared file system, shut down the
>> > Postgres server on that machine, and then start up the
>> > Postgres server on the machine that cannot write to the
>> > shared file system, and thereafter, *only query* the database.
>>
>
> Postgres isn't really designed to work this way. It expects to have
> write access and will occasionally still write stuff to disk even for
> read-only queries.
>
> It won't work even a little bit before 8.3. For 8.3 or later you could
> maybe make it work using vacuum freeze but there's no facility to
> verify that it's really frozen everything and you'll still be taken by
> surprise by queries which try to use temporary space for large sorts
> or commands which start transactions that you didn't realize were
> necessary.
>
> -- greg http://mit.edu/~gsstark/resume.pdf