Re: array_agg() NULL Handling

Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com> writes:
> 2010/9/1 Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>:
>> Well, you can build your own version of array_agg with the same
>> implementation, except you mark the transition function as strict ...

> I am checking this now, and it is not possible - it needs a some
> initial value and there isn't possible to set a "internal" value.

Well, you can cheat a bit ...

regression=# create or replace function array_agg_transfn_strict(internal, anyelement) returns internal as 'array_agg_transfn' language internal immutable;
CREATE FUNCTION
regression=# create aggregate array_agg_strict(anyelement) (stype = internal,
sfunc = array_agg_transfn_strict, finalfunc = array_agg_finalfn);
CREATE AGGREGATE
regression=# create or replace function array_agg_transfn_strict(internal, anyelement) returns internal as 'array_agg_transfn' language internal strict immutable;
CREATE FUNCTION

regards, tom lane