"Tom Lane" <tgl@sss.pgh.pa.us> writes:
> This is important for making the world safe for hashed DISTINCT, since
> AFAICS we probably can't ever use hashing for DISTINCT ON --- its definition
> is too dependent on the assumption of sorting.
I don't think that's true. We could store the sort key in the hash along with
the resulting tuple and replace the resulting tuple iff the new sort key is
less than the old sort key.
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