Re: WAL shipping question

On Dec 5, 2007, at 1:39 PM, SHARMILA JOTHIRAJAH wrote:

>
>
> > This basically archives the data in the primary server
> itself...right!!!
> > But how can I set up continuous archiving from primary to a
> directory
> > (WAL archive directory) on the stand-by server ?
>
> >>The closest thing to a worked out example of how to do this I'm
> aware of
> >>is at http://archives.postgresql.org/sydpug/2006-10/msg00001.php
>
> I tried this example
> I have the primary and standby server setup. The primary server is
> archiving the wal segments in the standby server's directory. My
> question is that, as per that example in step 15 the standby server
> should gives messages in its log whenever some WAL activity is
> triggered in the master. I see the archive directory in standby
> server getting filled up, but there are no log messages generated.
> Whay? What am I missing here?

Make sure you're looking in the whatever location you have postgres
configured to log in. If you're still not seeing log messages there,
then you've done something wrong.

> Also what does step 16 mean in that above example?
> " To initiate a failover from the master to the slave, create the
> 'trigger file':
> touch ~/pg82demo/trigger
> This should immediately cause the slave to finish processing archived
> segments, exit recovery mode, and come up ready for use "

touch is a *nix utility (maybe on windows, too?) that simply creates
a file if it doesn't exist. In the example standby implementation in
the linked post, the recovery.sh script looks for the existence of
that file named trigger in pg82demo/ and, if it sees it, brings the
standby out of recovery mode and into normal operation.
>
>
> Does the wal archives are applied to the standby server at this
> point and it has all the
> contents(tables,indexes,tabledata etc) at this point?

If you're not getting log output to the effect of wals being
replayed, then no.

Erik Jones

Software Developer | Emma®
erik(at)myemma(dot)com
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