Re: Synchronous Log Shipping Replication

On Tue, 2008-09-09 at 20:59 +0200, Zeugswetter Andreas OSB sIT wrote:
> All in all a useful streamer seems like a lot of work.

I mentioned some time ago an alternative idea of having the slave
connect through a normal SQL connection and call a function which
streams the WAL file from the point requested by the slave... wouldn't
that be feasible ? All the connection part would be already there, only
the streaming function should be implemented. It even could use SSL
connections if needed. Then you would have one normal backend per slave,
and they should access either the files directly or possibly some shared
area where the WAL is buffered for this purpose... the streaming
function could also take care of signaling the "up-to-dateness" of the
slaves in case of synchronous replication.

There could also be some system table infrastructure to track the
slaves. There could also be some functions to stream the files of the DB
through normal backends, so a slave could be bootstrapped all the way
from copying the files through a simple postgres backend connection...
that would make for the easiest possible setup of a slave: configure a
connection to the master, and hit "run"... and last but not least the
same interface could be used by a PITR repository client for archiving
the WAL stream and occasional file system snapshots.

Cheers,
Csaba.