Re: question about wal and point in time recovery

Tom Lane wrote:
> > can the log be modified before recovery occurs.
>
> Not easily.  If you were to hack any one log entry, you'd have to
> recompute the CRC checksum for it, and there's no way at all to make
> a change that would involve changing the size of a log entry.  So
> really the only useful option you have here is to stop recovery short
> of a particular log entry you don't like.
>
> > my biggest concern is that somebody in my org, for example, deletes a
> > field or fudges an update query that changes a foreign key to a single
> > value - and therefore destroys table links.  so what if this happens
> > and nobody notices it for several weeks?
>
> There is no automatic recovery mechanism that is going to help you in
> such a scenario.  You can't expect to undo a long-ago change and not
> have that break some unknown number of consequent decisions.

I think it might be easier to somehow hack the binary that reads the WAL
file on recovery to adjust how it handles a certain WAL entry, rather
than modifying the WAL files itself.

--
  Bruce Momjian                        |  http://candle.pha.pa.us
  pgman@candle.pha.pa.us               |  (610) 359-1001
  +  If your life is a hard drive,     |  13 Roberts Road
  +  Christ can be your backup.        |  Newtown Square, Pennsylvania 19073