Re: [ADMIN] Is it possible to run multiple postmasters?h

> From: Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
>
> KD> About 2 weeks ago, I reported a problem with 6.5.3 on Linux version
> KD> 2.2.7-1.23smp (VA-Research). Basically, we have one gigabyte scale
> KD> table that will not index on the text field, although it does index on
> KD> a char(1) and a date field.
>
> Sorry, I don't remember this.

I checked psql-bugs to be sure:

>o From: Karl DeBisschop <kdebisschop(at)range(dot)infoplease(dot)com>
>o To: pgsql-bugs(at)postgresql(dot)org
>o Subject: problem creating index in 6,5,3
>o Date: Fri, 17 Dec 1999 12:41:20 -0500

Tom Lane responded, but I've had no comments since I did what he
recommended and posted results.

Also (though this one is somehow not in the archive):

>Date: Tue, 21 Dec 1999 08:16:11 -0500
>From: Karl DeBisschop <kdebisschop(at)alert(dot)infoplease(dot)com>
>To: pgsql-general(at)postgresql(dot)org
>In-reply-to: <8703(dot)945457153(at)sss(dot)pgh(dot)pa(dot)us> (message from Tom Lane on Fri, 17
> Dec 1999 13:59:13 -0500)
>Subject: [GENERAL] Cannot index large table in 6.5.3 on Linux
>Reply-to: kdebisschop(at)alert(dot)infoplease(dot)com
>Sender: owner-pgsql-general(at)postgresql(dot)org

I can send the complete text of these to you if you are interested,
but I don't want to hit the mailing lists with somewhat lengthy
messages that have already been posted once.

> > We been unable to find the cause of the problem ourselves, and the user
> > community and developers have not yet come up with a solution.
> >
> > So, as a work-around we contemplated running two postmasters on the
> > same machine, with different ports and data directories - one would be
> > 6.5.3 which has recent bug fixes that we like alot and a second which
> > would be 6.5.1 which can successfully create the index that 6.5.3
> > cannot.
>
> It is very strange something would work on 6.5.1 and not on 6.5.3. The
> changes are _very_ small between the two releases, and I would doubt
> anything that would show up as a bug.

Yes, it is strange. Nonetheless, it seems to be so.

> > I've been able to get both postmasters running, but the second one to
> > start seems to interfere with operation of the first. So my quation
> > is, can I run two postmasters simultaneously on the same machine?
> > And if so, how?
>
> Yes you can. Use a postmaster parameter to specify a different port
> number, and use that port number in your connections.

I have done that, but once the second postmaster is running, frontends
(e.g., psql) seem to be unable to connect to the original postmaster:

# sudo /etc/rc.d/init.d/postgresql start
Checking postgresql installation: looks good!
Starting postgresql service: postmaster [25125]

# ps -fu postgres
UID PID PPID C STIME TTY TIME CMD
postgres 25125 1 0 13:52 ? 00:00:00 /usr/bin/postmaster -i -S -D/var/lib/pgsql

# psql -l
datname |datdba|encoding|datpath
---------+------+--------+---------
template1| 10002| 0|template1
test | 5313| 0|test
regdb | 5313| 0|regdb
biobase | 5313| 0|biobase
task | 5313| 0|task
feature | 5313| 0|feature
id | 5313| 0|id
(7 rows)

# sudo /etc/rc.d/init.d/postgresql651 start
Checking postgresql installation: looks good!
Starting postgresql service: failed.

# ps -fu postgres
UID PID PPID C STIME TTY TIME CMD
postgres 25125 1 0 13:52 ? 00:00:00 /usr/bin/postmaster -i -S -D/var/lib/pgsql
postgres 27007 1 0 15:17 ? 00:00:00 /opt/postgresql/bin/postmaster -p 5433 -S -D/opt/postgresql/data

# psql -l
Connection to database 'template1' failed.
connectDB() -- connect() failed: Connection refused
Is the postmaster running at 'localhost' and accepting connections on Unix socket '5432'?

# psql -p 5432 -l
Connection to database 'template1' failed.
connectDB() -- connect() failed: Connection refused
Is the postmaster running at 'localhost' and accepting connections on Unix socket '5432'?

# psql -p 5433 -l
datname |datdba|encoding|datpath
---------+------+--------+---------
template1| 10002| 0|template1
(1 row)

So I seem to be missing something (note that 'Starting postgresql
service: failed.' is actually a failure of the RedHat-based init
script, postmaster itself actually does start up as shown by the `ps
` output.

Karl DeBisschop