We really need point-in-time recovery, removal of the need to vacuum, and more full-featured replication. Hopefully most can be addressed in 7.2. > Hi all, > > Out of curiosity, does anyone know of any projects that are presently > creating PostgreSQL database recovery tools? > > For example database corruption recovery, Point In Time restoration, and > such things? > > It might be a good project for GreatBridge to look into if no-one else > is doing it already. > > Regards and best wishes, > > Justin Clift > Database Administrator > > Tom Lane wrote: > > > > As the WAL stuff is currently constructed, the system will refuse to > > start up unless the checkPoint field of pg_control points at a valid > > checkpoint record in the WAL log. > > > > Now I know we write and fsync the checkpoint record before we rewrite > > pg_control, but this still leaves me feeling mighty uncomfortable. > > See past discussions about how fsync order doesn't necessarily mean > > anything if the disk drive chooses to reorder writes. Since loss of > > the checkpoint record means complete loss of the database, I think we > > need to work harder here. > > > > What I'm thinking is that pg_control should have pointers to the last > > two checkpoint records, not only the last one. If we fail to read the > > most recent checkpoint, try the one before it (which, obviously, means > > we must keep the log files long enough that we still have that one too). > > We can run forward from there and redo the intervening WAL records the > > same as we would do anyway. > > > > This would mean an initdb to change the format of pg_control. However > > I already have a couple other reasons in favor of an initdb: the > > record-length bug I mentioned yesterday, and the bogus CRC algorithm. > > I'm not finished reviewing the WAL code, either :-( > > > > regards, tom lane > -- Bruce Momjian | http://candle.pha.pa.us [EMAIL PROTECTED] | (610) 853-3000 + If your life is a hard drive, | 830 Blythe Avenue + Christ can be your backup. | Drexel Hill, Pennsylvania 19026
