On 2019-11-01 15:41, Robert Haas wrote:
> On a related note, why do we store typbyval in the catalog anyway
> instead of inferring it from typlen and maybe typalign? It seems like
> a bad idea to record on disk the way we pass around values in memory,
> because it means that a change to how values are passed around in
> memory has ramifications for on-disk compatibility.
This sounds interesting. It would remove a pg_upgrade hazard (in the
long run).
There is some backward compatibility to be concerned about. This change
would require extension authors to change their code to insert #ifdef
USE_FLOAT8_BYVAL or similar, where currently their code might only
support one method or the other.
> rhaas=# select typname, typlen, typbyval, typalign from pg_type where
> typlen in (1,2,4,8) != typbyval;
There are also typlen=6 types. Who knew. ;-)
> typname | typlen | typbyval | typalign
> ----------+--------+----------+----------
> macaddr8 | 8 | f | i
> (1 row)
This might be a case of the above issue: It's easier to just make it
pass by reference always than deal with a bunch of #ifdefs.
--
Peter Eisentraut http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
