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

>   From: Bruce Momjian <pgman@candle.pha.pa.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@range.infoplease.com>
>o To: pgsql-bugs@postgresql.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@alert.infoplease.com>
>To: pgsql-general@postgresql.org
>In-reply-to: <8703.945457153@sss.pgh.pa.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@alert.infoplease.com
>Sender: owner-pgsql-general@postgresql.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