On 2013-03-28 21:02:06 -0400, Robert Haas wrote: > On Wed, Mar 27, 2013 at 10:15 AM, Andres Freund <and...@2ndquadrant.com> > wrote: > > On 2013-03-27 10:06:19 -0400, Robert Haas wrote: > >> On Mon, Mar 18, 2013 at 4:31 PM, Greg Smith <g...@2ndquadrant.com> wrote: > >> > to get them going again. If the install had checksums, I could have > >> > figured > >> > out which blocks were damaged and manually fixed them, basically go on a > >> > hunt for torn pages and the last known good copy via full-page write. > >> > >> Wow. How would you extract such a block image from WAL? > >> > >> That would be a great tool to have, but I didn't know there was any > >> practical way of doing it today. > > > > Given pg_xlogdump that should be doable with 5min of hacking in 9.3. Just > > add > > some hunk to write out the page to the if (config->bkp_details) hunk in > > pg_xlogdump.c:XLogDumpDisplayRecord. I have done that for some debugging > > already. > > > > If somebody comes up with a sensible & simple UI for this I am willing to > > propose a patch adding it to pg_xlogdump. One would have to specify the > > rel/file/node, the offset, and the target file. > > Hmm. Cool. But, wouldn't the hard part be to figure out where to > start reading the WAL in search of the *latest* FPI?
I'd expect having to read the whole WAL and write out all the available FPIs. You might be able to a guess a bit based on the LSN in the header. Greetings, Andres Freund -- Andres Freund http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Training & Services -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
