Re: RFC: Restructuring pg_aggregate

Tom Lane wrote:
> Hiroshi's "DROP_COLUMN_HACK" was essentially along this line, but
> I think he made a representational mistake by trying to change the
> attnums of dropped columns to be negative values. 

Negative attnums had 2 advantages then. It had a big
advantage that initdb isn't needed. Note that it was
only a trial hack and there was no consensus on the way.
It was very easy to change the implementation to use
attisdropped. OTOH physical/logical attnums approach
needed the change on pg_class, pg_attribute and so
I've never had a chance to open the patch to public. 
It was also more sensitive about oversights of needed 
changes than the attisdropped flag approach. 

> That means that
> a lot of low-level places *do* need to know about the dropped-column
> convention, else they can't make any sense of tuple layouts.

Why ? As you already mentioned, there were not that many places
to be changed.

Well what's changed since then ?

regards,
Hiroshi Inoue