Re: [v9.2] Start new timeline for PITR

On 6/10/11 12:34 PM, Robert Haas wrote:
> On Fri, Jun 10, 2011 at 2:53 PM, Josh Berkus <josh(at)agliodbs(dot)com> wrote:
>>> Let's imagine we're taking filesystem snapshots each day by whatever
>>> means. We're also archiving xlogs, but only have space for 48 hours'
>>> worth. Now we want to recover to 3 days ago, but there are no WALs
>>> from that time, so we do a crash recovery from the filesystem
>>> snapshot. Doing continuous archiving from this conflicts with the
>>> existing WALs, which we solve by creating a new timeline.
>>
>> How is this different from just changing the recovery_command?
>
> *scratches head*
>
> How is it the same?

Well, presumably I can just change recovery_command to recover from an
empty directory. Then the PITR copy will just come up as soon as it
finishes processing local snapshot WAL, and it'll start its own
timeline. How is this different from what the patch does?

--
Josh Berkus
PostgreSQL Experts Inc.
http://pgexperts.com