On Fri, Jul 08, 2005 at 09:38:07AM +0900, ITAGAKI Takahiro wrote:
> Hans-J|rgen Schvnig <[EMAIL PROTECTED]> 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)

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