Re: [COMMITTERS] pgsql-server/ oc/src/sgml/runtime.sgml rc/back

Tom Lane wrote:
> Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> writes:
> > Tom, do we really want to add a GUC that is used just for comparison of
> > performance? I know we have the seqscan on/off, but there are valid
> > reasons to do that. Do you think there will be cases where it will
> > faster to have this hash setting off?
>
> Sure --- that's why the planner code is going to great lengths to try to
> choose the faster one. Even if I didn't think that, it'll be at least
> as useful as, say, enable_indexscan.

Oh, OK. Just checking. I was confused about your commit message
because you seemed to be saying it was mostly for testing, and I thought
you meant testing to see if the hash code is an improvement over what we
had, rather than to see if the hash code is an improvement over the
sequential scan GROUP BY path, which is still in the code.

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