Alvaro Herrera <alvherre@alvh.no-ip.org> writes:
> On 2021-Nov-25, Tom Lane wrote:
>> Really? AFAICS the WAL record contains the correct value, or at least
>> we should define that one as being correct, for precisely this reason.
> I don't know what is the correct value for a record that comes exactly
> after the page header. But here's a patch that fixes the problem; and
> if a standby replays WAL written by an unpatched primary, it will be
> able to read past instead of dying of FATAL.
Meh ... but given the simplicity of the write-side fix, maybe changing
it is appropriate.
However, this seems too forgiving:
+ if (xlrec->overwritten_lsn != state->overwrittenRecPtr &&
+ xlrec->overwritten_lsn - SizeOfXLogShortPHD != state->overwrittenRecPtr &&
+ xlrec->overwritten_lsn - SizeOfXLogLongPHD != state->overwrittenRecPtr)
The latter two cases should only be accepted if overwrittenRecPtr is
exactly at a page boundary.
regards, tom lane