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
(972) 813-5004
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