Re: Building infrastructure for B-Tree deduplication that recognizes when opclass equality is also equivalence

Peter Geoghegan <pg@bowt.ie> writes:
> I was thinking of stashing an "equality is precise" flag in the
> metapage of each nbtree index, since we will only determine this once,
> at CREATE INDEX time.

Sure.

> That would make it fairly natural for the
> planner to ask about the "equality is precise"-ness of the index at
> the same point that it calls _bt_getrootheight(): within
> get_relation_info().

The planner will almost certainly want to ask the opclass directly,
because most of the places where it wants to know this sort of thing
about operator behavior have nothing to do with indexes.

            regards, tom lane