Re: Warning: Don't delete those /tmp/.PGSQL.* files

On 25 Nov 2000, at 17:35, Tom Lane wrote:

> > So, I began restarting pgsql w/a line like
>
> > rm -f /tmp/.PGSQL.* && postmaster -i >log 2>log &
>
> > Which works great. Except that I *kept* using this for two weeks
> > after the view problem (damn that bash up-arrow laziness!), and
> > yesterday, used it to restart PostgreSQL except (oops!) it was
> > already running.
>
> > Results: no database at all. All classes (tables/views/etc) returned
> > 0 records (meaning that no tables showed up in psql's \d, since
> > pg_class returned nothing.)
>
> Ugh. The reason that removing the socket file allowed a second
> postmaster to start up is that we use an advisory lock on the socket
> file as the interlock that prevents two PMs on the same port number.
> Remove the socket file, poof no interlock.
>
> *However*, there is a second line of defense to prevent two
> postmasters in the same directory, and I don't understand why that
> didn't trigger. Unless you are running a version old enough to not
> have it. What PG version is this, anyway?

7.1devel, from about 1 week ago.

> Assuming you got past both interlocks, the second postmaster would
> have reinitialized Postgres' shared memory block for that database,
> which would have been a Bad Thing(tm) ... but it would not have led to
> any immediate damage to your on-disk files, AFAICS. Was the database
> still hosed after you stopped both postmasters and started a fresh
> one? (Did you even try that?)

Yes, I stopped both, rebooted machine, restarted postmaster.
Rebooted machine, used just postgres, tried to vacuum, tried to
dump, etc. Always the same story.

--
Joel Burton, Director of Information Systems -*- jburton(at)scw(dot)org
Support Center of Washington (www.scw.org)