Tom Lane wrote:
> I've pretty much finished the project I got a bee in my bonnet about
> last week, which is to teach SELECT DISTINCT how to (optionally) use
> hashing for grouping in the same way that GROUP BY has been able to do
> for awhile.
>
> There are still two places in the system that hard-wire the use of
> sorting for duplicate elimination:
>
> * Set operations (UNION/INTERSECT/EXCEPT)
>
> * Aggregate functions with DISTINCT
>
> I'm thinking of trying to fix set operations before I leave this topic,
> but I'm not sure it's worth the trouble to change DISTINCT aggregates.
> They'd be a lot more work (since there's no executor infrastructure
> in place that could be used) and the return on investment seems low.
>
> Comments?
>
> regards, tom lane
>
>
i feel it exactly the same way.
DISTINCT has been a place people wanted to see fixed for a while but set
operations are nothing I would really worry about.
what we have now is absolutely fine.
given the list of more important issues, i'd vote for something else.
best regards,
hans
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