> I suspect the tuple at (0,1) has been the subject of a failed update.


> Your problem here is that you're mistaking the t_ctid field of a tuple
> header for the tuple's address.  It is not that; it's really just garbage
> normally, and is only useful to link forward to the next version of the
> row from an outdated tuple.  I think we do initialize it to the tuple's
> own address during an INSERT, but either a completed or failed UPDATE
> would change it.

Thanks.  That helps clarify the comments in htup_details.h, actually.

> I do not think there is any way to get the true address of a heap tuple
> out of a composite Datum manufactured from the tuple.  Most of the other
> system columns can't be gotten from a composite Datum either, because of
> the field overlay in HeapTupleHeaderData's union t_choice.

Well shoot.  That kinda spoils my plans.

What about this?  Is the tuple currently being evaluated (I suppose in the
case of a sequential scan) available in the context of a function call?

Thanks again for your time!  It's much appreciated.


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