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Re: After ~Crash Sequence not correct

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: "Mikheev, Vadim" <vmikheev(at)SECTORBASE(dot)COM>
Cc: "Henshall, Stuart - WCP" <SHenshall(at)westcountrypublications(dot)co(dot)uk>, pgsql-bugs(at)postgreSQL(dot)org
Subject: Re: After ~Crash Sequence not correct
Date: 2001-12-19 18:48:33
Message-ID: 1934.1008787713@sss.pgh.pa.us (view raw or flat)
Thread:
Lists: pgsql-bugs
"Mikheev, Vadim" <vmikheev(at)SECTORBASE(dot)COM> writes:
> It was made to avoid WAL-loging on each nextval call, ie it should work
> like OID pre-fetching: value stored in WAL must always "exceed" values
> returned by nextval so on the after-crash-restart sequence should be
> advanced to value which was never returned by nextval (for non-cycled
> sequences). Maybe I made some mistakes in implementation?

Oh, okay.  What I saw was that the next nextval() after restart was
higher than what I was expecting; but that's correct given the prefetch
behavior.

But we've seen several reports wherein the value appeared to go
backwards after a crash.

Stuart, you weren't running with -F (fsync off) by any chance, were you?

			regards, tom lane

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