Re: Cascade Standby Configuration in 9.2.4

On Apr 1, 2014, at 5:20 PM, Murthy Nunna <mnunna(at)fnal(dot)gov> wrote:

> Thanks for the clarification Scott... What is the restore_command in recovery.conf does in case of streaming replication if it doesn't need logs available locally on the slave machine.

It copies the files. It has no way of knowing whether or not there's a WAL-shipping replica out there somewhere which needs them.

> Do you think if the streaming falls behind, then slave will request master to ship logs??????

The slave does not request the master to ship logs. The slave, when started uses the WAL files it finds in its locally-available WAL archive, then starts streaming from the master, which requires that there not be a gap between its local copies and what's still available on the master.

This is all covered in the documentation:

<http://www.postgresql.org/docs/9.2/static/high-availability.html>

--
Scott Ribe
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http://www.elevated-dev.com/
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