Re: [BUG] Panic due to incorrect missingContrecPtr after promotion

We see another occurrence of this bug with the last patch applied in 13.7.

After a promotion we observe the following in the logs:

2022-05-25 00:35:38 UTC::@:[371]:PANIC: xlog flush request 10/B1FA3D88 is not satisfied --- flushed only to 7/A8000060
2022-05-25 00:35:38 UTC:172.31.26.238(38610):administrator(at)postgres:[23433]:ERROR: current transaction is aborted, commands ignored until end of transaction block

However, The logs do not show "LOG: successfully skipped missing contrecord",
therefore we know that VerifyOverwriteContrecord
is not being called to invalidate the missingContrecPtr.

VerifyOverwriteContrecord(xl_overwrite_contrecord *xlrec, XLogReaderState *state)
{
if (xlrec->overwritten_lsn != state->overwrittenRecPtr)
elog(FATAL, "mismatching overwritten LSN %X/%X -> %X/%X",
(uint32) (xlrec->overwritten_lsn >> 32),
(uint32) xlrec->overwritten_lsn,
(uint32) (state->overwrittenRecPtr >> 32),
(uint32) state->overwrittenRecPtr);

/* We have safely skipped the aborted record */
abortedRecPtr = InvalidXLogRecPtr;
missingContrecPtr = InvalidXLogRecPtr;

ereport(LOG,
(errmsg("successfully skipped missing contrecord at %X/%X, overwritten at %s",
(uint32) (xlrec->overwritten_lsn >> 32),
(uint32) xlrec->overwritten_lsn,
timestamptz_to_str(xlrec->overwrite_time))));

We think it's because VerifyOverwriteContrecord was not
called which is why we see this behavior.

Are there are other places where missingContrecPtr
should be invalidated, such as after a successful promotion?

--
Sami Imseih
Amazon Web Services