On 2013-06-22 15:58:35 +0200, Cédric Villemain wrote: > > A differential backup resulting from a bunch of WAL between W1 and Wn > > would help to recover much faster to the time of Wn than replaying all > > the WALs between W1 and Wn and saves a lot of space. > > > > I was hoping to find some time to dig around this idea, but as the > > subject rose here, then here are my 2¢! > > something like that maybe : > ./pg_xlogdump -b \ > ../data/pg_xlog/000000010000000000000001 \ > ../data/pg_xlog/000000010000000000000005| \ > grep 'backup bkp' | awk '{print ($5,$9)}'
Note that it's a bit more complex than that for a number of reasons: * we don't log full page images for e.g. new heap pages, we just set the XLOG_HEAP_INIT_PAGE flag on the record * there also are XLOG_FPI records * How do you get a base backup as the basis to apply those to? You need it to be recovered exactly to a certain point... But yes, I think something can be done in the end. I think Heikki's pg_rewind already has quite a bit of the required logic. 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