This is a discussion on Re: [COMMITTERS] pgsql: Fix race condition in multixact code: it's possible within the Pgsql Patches forums, part of the PostgreSQL category; --> Does this need to be backpatched? --------------------------------------------------------------------------- Tom Lane wrote: > Log Message: > ----------- > Fix race condition ...
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| Does this need to be backpatched? --------------------------------------------------------------------------- Tom Lane wrote: > Log Message: > ----------- > Fix race condition in multixact code: it's possible to try to read a > multixact's starting offset before the offset has been stored into the > SLRU file. A simple fix would be to hold the MultiXactGenLock until the > offset has been stored, but that looks like a big concurrency hit. Instead > rely on knowledge that unset offsets will be zero, and loop when we see > a zero. This requires a little extra hacking to ensure that zero is never > a valid value for the offset. Problem reported by Matteo Beccati, fix > ideas from Martijn van Oosterhout, Alvaro Herrera, and Tom Lane. > > Modified Files: > -------------- > pgsql/src/backend/access/transam: > multixact.c (r1.9 -> r1.10) > (http://developer.postgresql.org/cvsw...r1=1.9&r2=1.10) > > ---------------------------(end of broadcast)--------------------------- > TIP 6: explain analyze is your friend > -- Bruce Momjian | http://candle.pha.pa.us pgman@candle.pha.pa.us | (610) 359-1001 + If your life is a hard drive, | 13 Roberts Road + Christ can be your backup. | Newtown Square, Pennsylvania 19073 ---------------------------(end of broadcast)--------------------------- TIP 1: if posting/reading through Usenet, please send an appropriate subscribe-nomail command to majordomo@postgresql.org so that your message can get through to the mailing list cleanly |
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| Bruce Momjian <pgman@candle.pha.pa.us> writes: > Does this need to be backpatched? No. regards, tom lane ---------------------------(end of broadcast)--------------------------- TIP 9: In versions below 8.0, the planner will ignore your desire to choose an index scan if your joining column's datatypes do not match |