Re: tuptoaster.c must *not* use SnapshotAny

Jan Wieck <janwieck@yahoo.com> writes:
>     Really?  So  what  you're  saying  means that while vacuum is
>     running there's a window where one tuple can  exist  multiple
>     times

Moving a tuple in VACUUM isn't fundamentally different from an UPDATE.
You need a visibility rule to tell you which version of the tuple to
pay attention to.  Right now, TOAST hasn't got one.

Per later discussion, Andreas is right that SnapshotSelf won't do.
I think we need a new tqual.c routine just for TOAST.  (The alternative
would be for TOAST to know which snapshot was used to find the main-
table tuple, but that doesn't seem workable.)
        regards, tom lane