Re: Using RSYNC for replication? - Mailing list pgsql-general

From Greg Stark
Subject Re: Using RSYNC for replication?
Date
Msg-id 87lm0yqqmy.fsf@stark.dyndns.tv
Whole thread Raw
In response to Re: Using RSYNC for replication?  ("Shridhar Daithankar<shridhar_daithankar@persistent.co.in>" <shridhar_daithankar@persistent.co.in>)
List pgsql-general
"Shridhar Daithankar<shridhar_daithankar@persistent.co.in>" <shridhar_daithankar@persistent.co.in> writes:

> That makes me wonder. How hard it is to create async replication based on WAL,
> assuming there is not one already.

What you describe below sounds like what Oracle calls a warm standby database.

It's not replication because you can't be doing separate operations in the
standby database and expect the logs from the original database to still apply
cleanly.

Even so it's an extremely useful configuration. It's allows instantaneous
fail-over to the standby database without having to restore from backups. And
Oracle lets you open the standby database read-only which is extremely useful
for doing large batch queries without slowing down your main OLTP database.

> Create a daemon that watches WAL dir. As soon as a new file is created, old
> file is copied at someplace else, which can also be dropped into WAL dir. of
> another installation and it will sync up.
>
> Assumming WAL naming notation/names can be tweaked by external program, is it
> correct idea of async notation? It should not be that hard to come up with
> such a daemon.

--
greg

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