On Fri, Jul 08, 2005 at 09:38:07AM +0900, ITAGAKI Takahiro wrote:
> Hans-J|rgen Schvnig <postgres@cybertec.at> wrote:
>
> > 64-bit XIDs seem to be an overkill - the only practical impact I can see
> > is an even larger tuple header (this can be an issue on large boxes too
> > - at least compared to Oracle).
>
> I agreed, too. The changes of XIDs cannot be ignored because the overhead
> will be 32bytes per tuple.
>
> Avoiding overheads, can XIDs/CIDs be different bit length? For example,
> can XIDs/CIDs be changed to 48/16-bit or 40/24-bit?
Not unless you change the definition of HeapTupleFields
(src/include/access/htup.h). Alignment concerns would probably bite you
if you changed it, anyway.
--
Alvaro Herrera (<alvherre[a]alvh.no-ip.org>)
"Ninguna manada de bestias tiene una voz tan horrible como la humana" (Orual)