Re: [HACKERS] Database replication... - Mission Critical DBMS's -- Taking postgreSQL to the Enterprise Computing level...

On Tue, Oct 29, 2002 at 03:56:46PM -0800, Greg Patnude wrote:

> I have read through all 7 chapters of the PG documentation and didn't see
> anything about replicating a postgreSQL database on a secondary database
> server and having the primary server push all data manipulations on through
> to the secondary server. The secondary server would be available (through
> the connect script) if the primary server died.
>
> Does anyone know of a reasonable means of synchronizing two (or more)
> postgreSQL database servers in order to maintain two COMPLETE concurrent
> copies of the same database ?

I think what you want is that any change, including schema changes,
&c., on the master database are echoed to the slave. I know rserv
can't do that, and I don't _think_ dbmirror can, either. But both of
those are possibilities. AFAIK, the contrib/rserv code is completely
broken in the 7.3 series, so dbmirror might be the free answer to
pick; rserv has a commercial cousin which we use.

The problem with these is that they send _data_ to the slave, and use
standard SQL statements. So sequences &c. are not carried over. You
need a script to do that. It's not an instantaneous failover.

On the other hand, if your client is comparing with Access, the
reliability will be so much better that perhaps some extra work in
the rare case of failure will be acceptable. It is for us, and we
have extremely stringent SLAs which constrain how long we could be
down if (heaven forfend!) our master database ever died.

A

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