On Mon, Aug 9, 2021 at 3:00 PM Robert Haas <robertmh...@gmail.com> wrote: > I decided to try writing a patch to use an end-of-recovery record > rather than a checkpoint record in all cases. > > The first problem I hit was that GetRunningTransactionData() does > Assert(TransactionIdIsNormal(CurrentRunningXacts->latestCompletedXid)). > > Unfortunately we can't just relax the assertion, because the > XLOG_RUNNING_XACTS record will eventually be handed to > ProcArrayApplyRecoveryInfo() for processing ... and that function > contains a matching assertion which would in turn fail. It in turn > passes the value to MaintainLatestCompletedXidRecovery() which > contains yet another matching assertion, so the restriction to normal > XIDs here looks pretty deliberate. There are no comments, though, so > the reader is left to guess why. I see one problem: > MaintainLatestCompletedXidRecovery uses FullXidRelativeTo, which > expects a normal XID. Perhaps it's best to just dodge the entire issue > by skipping LogStandbySnapshot() if latestCompletedXid happens to be > 2, but that feels like a hack, because AFAICS the real problem is that > StartupXLog() doesn't agree with the rest of the code on whether 2 is > a legal case, and maybe we ought to be storing a value that doesn't > need to be computed via TransactionIdRetreat().
Anyone have any thoughts about this? -- Robert Haas EDB: http://www.enterprisedb.com
