2015-10-28 18:38 GMT+01:00 Tom Lane <t...@sss.pgh.pa.us>: > Marko Tiikkaja <ma...@joh.to> writes: > > Here's a patch for the aggregate function outlined by Corey Huinker in > > CADkLM=foA_oC_Ri23F9PbfLnfwXFbC3Lt8bBzRu3=cb77g9...@mail.gmail.com . I > > called it "onlyvalue", which is a horrible name, but I have nothing > > better to offer. (Corey called it "only", but that doesn't really work > > since ONLY is a fully reserved keyword.) > > On the name front, maybe think "single" rather than "only"? This might > lead to "single()" or "single_value()", or "singleton()" if you want to > sound highbrow. >
this function should to have some distinguish name than other aggregates because important work of this func is not some calculation but some constraint check. > On the semantics front, I'm not sure that I like excluding nulls from the > input domain. I'd rather that it acted like IS NOT DISTINCT, ie, nulls > are fine as long as all the input values are nulls. The implementation > would need some work for that. > > regards, tom lane > > > -- > Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) > To make changes to your subscription: > http://www.postgresql.org/mailpref/pgsql-hackers >
