Re: PGSQL internals question...

Tom Lane wrote:
>
> Chris Bitmead <chrisb(at)nimrod(dot)itg(dot)telstra(dot)com(dot)au> writes:
> > inside the backend, if I have a TupleTableSlot, can I find out from what
> > basetable it is referring to or not?
>
> Since it's not necessarily referring to any table at all, the general
> answer is "no". Do you have a reason to assume that the slot is
> holding a tuple directly fetched from disk, rather than constructed
> on-the-fly?

I'm looking at implementing classoid and I was looking around inside
ExecProject, wondering if this would be a good place to create the
magical classoid field. If I understand ExecProject it takes some "real"
tables and mangles them into a single result tuple. Do I know if it is a
tuple direct from disk? It seemed that way, but perhaps you can tell me?

The other approach I'm looking at is to add a Relation field to
TupleTableSlot which is populated inside of XXXScan or whatever, which
can be lifted out inside ExecProject. Do you think I'm on the right
track?