Re: get rid of RM_HEAP2_ID

On Wed, Oct 15, 2025 at 6:55 AM Michael Paquier <michael@paquier.xyz> wrote:
>
> On Tue, Oct 14, 2025 at 03:20:16PM +0300, Heikki Linnakangas wrote:
> > I'm not sure I agree with the premise that we should try to get rid of
> > RM_HEAP2_ID. There's nothing wrong with that scheme as such. As an
> > alternative, we could easily teach e.g pg_waldump to treat RM_HEAP_ID and
> > RM_HEAP2_ID the same for statistics purposes.
>
> Yeah, I'd rather keep heap2 as well.  As long as there is more room
> for the record IDs, we're still going to need it in the long run.

Okay, I'll drop that aspect.

> We could move out xl_xid, which should not be required for all
> records, shaving 4 bytes from the base XLogRecord.  I'm afraid of the
> duplication this would create if we push this data to each RMGR, which
> would, I guess, require a new RMGR callback to retrieve this field on
> a per-record basis.  But perhaps it would not be that bad.

I've wondered if it would be possible to make xl_tot_len a varint that
starts in the last byte of the header, with the next bytes being like
XLogRecordDataHeader[Short|Long], but likewise using a varint.

--
John Naylor
Amazon Web Services