On Sat, Jan 27, 2007 at 12:11:59AM +0000, Gregory Stark wrote: > If this isn't run for a very long time (how long depends on how busy the > database is, but even on extremely large databases it's usually a matter of > months, on more normal databases it would be years) then very old records seem > to suddenly disappear. There is a way to recover data that this has happened > to though as long as you don't run vacuum after the data has disappeared. > > To repeat: If you think this may have happened DO NOT run vacuum now.
Actually, for XID wraparound a VACUUM may actually be the right thing. I looked at this (with guidence from Tom) and we came to the conclusion that XID wraparound will hide tuples older than 2 billion transaction, but VACUUM will mark as frozen anything newer than 3 billion transactions, so for 1 billion transactions you can actually get your data back. Expect for things like uniqueness guarentees, but they're solvable. Not that I'm saying that the OP has this issue... Have a nice day, -- Martijn van Oosterhout <kleptog@svana.org> http://svana.org/kleptog/ > From each according to his ability. To each according to his ability to > litigate.
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