On 21 May 2015 at 09:20, Andrew Gierth <and...@tao11.riddles.org.uk> wrote: >>>>>> "Dean" == Dean Rasheed <dean.a.rash...@gmail.com> writes: > > >> 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. > > Dean> Actually using ROLLUP the output volume only grows linearly with > Dean> N. I tend to think that having such a large number of grouping > Dean> sets would be unlikely, however, it seems wrong to be putting an > Dean> arbitrary limit on it that's significantly smaller than the > Dean> number of columns allowed in a table. > > Limit on what exactly? > > Consider that in both MSSQL 2014 and Oracle 12 the limit on the number > of arguments in a GROUPING() expression is ... 1. >
Actually Oracle haven't quite followed the standard. They have 2 separate functions: GROUPING() which only allows 1 parameter, and GROUPING_ID() which allows multiple parameters, and returns a bitmask like our GROUPING() function. However, their GROUPING_ID() function seems to return an arbitrary precision number and allows an arbitrary number of parameters (well, I tested it up 70 to prove it wasn't a 64-bit number). 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
