Horton

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

Kyotaro Horiguchi <horikyota.ntt@gmail.com>

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From: Kyotaro Horiguchi <horikyota.ntt@gmail.com>
To: simseih@amazon.com
Cc: alvherre@alvh.no-ip.org, pgsql-hackers@postgresql.org
Date: 2022-02-24T08:27:03Z
Lists: pgsql-hackers 
At Thu, 24 Feb 2022 16:26:42 +0900 (JST), Kyotaro Horiguchi <horikyota.ntt@gmail.com> wrote in 
> So, actually WAL did not ended in an incomplete record.  I think
> FinishWalRecover is the last place to do that. (But it could be
> earlier.)

After some investigation, I finally concluded that we should reset
abortedRecPtr and missingContrecPtr at processing
XLOG_OVERWRITE_CONTRECORD.


--- a/src/backend/access/transam/xlogrecovery.c
+++ b/src/backend/access/transam/xlogrecovery.c
@@ -1953,6 +1953,11 @@ xlogrecovery_redo(XLogReaderState *record, TimeLineID replayTLI)
                                                LSN_FORMAT_ARGS(xlrec.overwritten_lsn),
                                                timestamptz_to_str(xlrec.overwrite_time))));
 
+               /* We have safely skipped the aborted record */
+               abortedRecPtr = InvalidXLogRecPtr;
+               missingContrecPtr = InvalidXLogRecPtr;
+
                /* Verifying the record should only happen once */
                record->overwrittenRecPtr = InvalidXLogRecPtr;
        }

The last check in the test against "resetting aborted record" is no
longer useful since it is already checked by
026_verwrite_contrecord.pl.

regards.

-- 
Kyotaro Horiguchi
NTT Open Source Software Center

Commits

  1. Prevent WAL corruption after a standby promotion.

  2. Fix "missing continuation record" after standby promotion