> postgres-8.4.0 and 8.4.2 are completely compatible. Does it also mean that
> replication will work fine from postgres-8.4.0 to postgres-8.4.2 means
> from a lower to higher release. Does that holds true for postgres-8.4.4 as
> well ??

Yes.

> Moreover, in the release notes of 8.4.2 (link below), its mentioned that 
> "A dump/restore is not required for those running 8.4.X unless you are having
> hash index" . Does that mean: if I am not using any hash index , then I 
> can upgrade to postgres-8.4.2 from postgres-8.4.0 simply without any need of 
> exporting my database schema and data in it before upgrading postgres and 
> then importing it back after upgrade.

Yes, that is correct. Going from one revision to another (where the last of the 
three version number changes) never requires a dump and a reload. Even if you 
have hash indexes, a dump and reload is not required, just a REINDEX after 
the upgrade has completed.

> won't it corrupt the data if I upgrade postgres db with my database
> schema/data in it ??

No: the only thing that is changing is the Postgres program itself. The 
underlying data is not changed, just the program that reads and writes 
that data is slightly changed, to fix bugs.

If I can further expound to this list some more best practices, you should 
be subscribed to the pgsql-announce mailing list so you hear about new 
released (of Postgres, Slony, and other Postgres-related programs). You 
may also wish to run check_postgres.pl with the new_version_pg action, 
which will give you a Nagios alert when your version of Postgres becomes 
out of date.

-- 
Greg Sabino Mullane greg at endpoint.com
End Point Corporation
PGP Key: 0x14964AC8
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