RE: PGSQL internals question...

> -----Original Message-----
> From: pgsql-hackers-owner@hub.org [mailto:pgsql-hackers-owner@hub.org]On
> Behalf Of Chris Bitmead
> 
> Would a non-existant attribute have a system attribute number? Where do
> you suggest this code should be that "pulls it out"?
>

CTID has a system attribute number SelfItemPointerAttributeNumber(-1).
Different from other system attributes it corresponds to an item(t_self)
in HeapTupleData not to an item(t_ctid) in HeapTupleHeaderData.
Please look at include/access/htup.h.
Probably heap_xxxx() functions in access/heap/heapam.c would have
to fill in the new system attribute. 

Regards.

Hiroshi Inoue
Inoue@tpf.co.jp