Running Multiple Postmasters

Hi,

I actually run with 2 posmasters, 7.2 & 7.4 with different "physical"
/var/lig/pgsql/data & /var/lig/pgsql/data2 with no problem. They have
different TCP/IP port and run well.
The $PG_DATA$ is not needed if you use "pg_ctl -D" form, so you can run
many postmaster at same times.

A question about that, there is an utility to use 2 different
postmaster in production with same version ?

regards,

Hello,

We do it all the time at Command Prompt. That is how we do the managed
shared hosting. Every customer gets a private
data directory that is on its own TCP port.

J

Clay Luther wrote:

I am wondering if it is possible, or even advisable, to run two
postmasters on a single system.

For example, we have an embedded system with a normal runtime
partition (called the "A") in which the PGDATA is /var/lib/pgsql/data.
We also have a offline partition which is a copy of the runtime
partition, but is mounted under /partB -- PGDATA here is
/partB/var/lib/pgsql/data.

During upgrades, we will alter the installation on the B partition,
then swap the paritions after a reboot.

However, during upgrades, we may need to migrate data from the A
partition databases to the B partition databases.

For database migrations, I was hoping I could do the following
(remember, a postmaster is already running on /var/lib/pgsql/data):

1) Alter the the postgresql.conf of the B partition PGDATA, setting
the tcp/ip port to 54321.
2) Start the "B" postmaster, pg_ctl -D /partB/var/lib/pgsql/data start
3) Use ODBC/JDBC to perform necessary migration from A databases to B
databases.
4) pg_ctl -D /partB/var/lib/pgsql/data stop
5) Set B postgresql.conf tcp/ip port to 5432.
6) Reboot (higher level systems will automatically swap the A and B
partitions, so B becomes A and A becomes the new B).

Conceptually clear, but I wanted to know if there was anything I
needed to be worried about.

Thanks.

---
Clay
claycle@cisco.com <mailto:claycle@cisco.com>
(972) 813-5004

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