Re: mark/restore failures on unsorted merge joins

Andrew Gierth <andrew@tao11.riddles.org.uk> writes:
> "Tom" == Tom Lane <tgl@sss.pgh.pa.us> writes:
>  Tom> Uh, why would you not just look to see if the ammarkpos/amrestrpos
>  Tom> fields are non-null?

> We don't (in the back branches) seem to have a pointer to the
> IndexAmRoutine handy, only the oid?

Oh, sorry, I misread your comment to be that you wanted to add a field
to IndexAmRoutine.  You're right, the real issue here is that
ExecSupportsMarkRestore lacks any convenient access to the needed info,
and we need to add a bool to IndexOptInfo to fix that.

I don't see any compelling reason why you couldn't add the field at
the end in the back branches; that's what we usually do to avoid
ABI breaks.  Although actually (counts fields...) it looks like
there's at least one pad byte after amcanparallel, so you could
add a bool there without any ABI consequence, resulting in a
reasonably natural field order in all branches.

            regards, tom lane