I suspect the tuple at (0,1) has been the subject of a failed update.
Yep.
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not that; it's really just garbage normally, and is only useful to link forward to the next version of the row from an outdated tuple.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.
