On 10 August 2017 at 15:26, Chris Travers <chris.trav...@gmail.com> wrote: > > > The bitwise comparison is interesting. Remember the error was: > > pg_xlogdump: FATAL: error in WAL record at 1E39C/E1117FB8: unexpected > pageaddr 1E375/61118000 in log segment 000000000001E39C000000E1, offset > 1146880 ... > Since this didn't throw a checksum error (we have data checksums disabled but > wal records ISTR have a separate CRC check), would this perhaps indicate that > the checksum operated over incorrect data?
No checksum error and this "unexpected pageaddr" doesn't necessarily mean data corruption. It could mean that when the database stopped logging it was reusing a wal file and the old wal stream had a record boundary on the same byte position. So the previous record checksum passed and the following record checksum passes but the record header is for a different wal stream position. I think you could actually hack xlogdump to ignore this condition and keep outputting and you'll see whether the records that follow appear to be old wal log data. I haven't actually tried this though. -- greg -- Sent via pgsql-hackers mailing list (firstname.lastname@example.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers