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Re: PITR - warm standby switchover question

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Fujii Masao wrote:
Hi,

On Wed, Apr 15, 2009 at 9:23 AM, Dan Hayes <dhayes501@xxxxxxxxx> wrote:
Excellent!  Thanks.  One other quick question...  What would happen if I
didn't delete the recovery.conf file?  Is that step just to prevent
accidentally restarting the server with it there?

recovery.conf is automatically renamed recovery.done by
postgres at the end of recovery, which would prevent
accidentally restarting warm-standby. So, you don't need to
delete or rename recovery.conf by hand after recovery.
Also, keep in mind that the ideal solution is not to create a stop file, but to get the last few WAL files that had not been archived prior to the main system going down and place them in the directory that pg_standby was copying files from. If you simply create a stopfile and have the system start up, you're likely to lose some transactions that were in any WAL files that had not yet been archived (at the very least, that's the currently-in-use WAL file at the time of the crash). While getting these files isn't always possible, the best practice would be to at least try... There are a variety of ways to provide for real-time replication of in-use WAL files, if losing transactions in a crash is not a viable option for you..

Once you've gotten the last few WAL's, you should see PostgreSQL automatically detect the end of WAL logs and start up - with or without the stopfile (so you can still create the stopfile)

Once the server has completed recovery, it won't come up in recovery again, since (as Fujii noted) PostgreSQL will rename recovery.conf to recovery.done - indicating that recovery has completed. It will also begin a new timeline, etc.

Generally speaking, after recovery completes, you probably want to create a warm-standby backup and then log subsequent WAL files to ease future recovery from WAL's on the "currently active" cluster.

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