Re: Non-replayable WAL records through overflows and >MaxAllocSize lengths

On Mon, 14 Mar 2022 at 18:14, Andres Freund <andres@anarazel.de> wrote:
>
> A random thought I had while thinking about the size limits: We could use the
> low bits of the length and xl_prev to store XLR_SPECIAL_REL_UPDATE |
> XLR_CHECK_CONSISTENCY and give rmgrs the full 8 bit of xl_info. Which would
> allow us to e.g. get away from needing Heap2. Which would aestethically be
> pleasing.

I just remembered your comment while going through the xlog code and
thought this about the same issue: We still have 2 bytes of padding in
XLogRecord, between xl_rmid and xl_crc. Can't we instead use that
space for rmgr-specific flags, as opposed to stealing bits from
xl_info?


Kind regards,

Matthias van de Meent