On 20 May 2015 at 19:41, Tom Lane <t...@sss.pgh.pa.us> wrote: > David Fetter <da...@fetter.org> writes: >> While kicking the tires on the new GROUPING() feature, I noticed that >> NUMERIC has no cast to bit(n). GROUPING() produces essentially a >> bitmap, although the standard mandates for some reason that it be a >> numeric type. > >> I was thinking it should produce NUMERIC rather than int4 as it does >> now in order to accommodate large numbers of columns, but the >> usefulness of the bitmap is greatly increased if there's a simple CAST >> to bit(n). > > Maybe INT8 would be a better choice than INT4? But I'm not sure there's > any practical use-case for more than 30 grouping sets anyway. Keep in > mind the actual output volume probably grows like 2^N. >
Actually using ROLLUP the output volume only grows linearly with N. I tend to think that having such a large number of grouping sets would be unlikely, however, it seems wrong to be putting an arbitrary limit on it that's significantly smaller than the number of columns allowed in a table. Regards, Dean -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
