Обсуждение: Aggregate binary AND

Hi,

Is there an aggregate binary AND function in postgres?  If not, is there a
way to write your own aggregate functions?  Examples?

- James

This worked for us in 7.something (don't need it anymore, but it should
still work).

You'll want to create one for INT8, INT2, etc.. if you are going to use
those as well...

CREATE AGGREGATE aggr_bitand ( BASETYPE = INT4, SFUNC1 = int4and, STYPE1 =
INT4);

On Thu, 1 Nov 2001, James Orr wrote:

> Hi,
>
> Is there an aggregate binary AND function in postgres?  If not, is there a
> way to write your own aggregate functions?  Examples?
>
> - James
>
>
> ---------------------------(end of broadcast)---------------------------
> TIP 5: Have you checked our extensive FAQ?
>
> http://www.postgresql.org/users-lounge/docs/faq.html
>

"James Orr" <james@lrgmail.com> writes:
> Is there an aggregate binary AND function in postgres?  If not, is there a
> way to write your own aggregate functions?  Examples?

The aggregate would be trivial given an underlying two-argument AND
function to build it from:

regression=# create aggregate booland ( basetype = bool,
regression(# sfunc = booland, stype = bool,
regression(# initcond = 'true' );
ERROR:  AggregateCreate: function 'booland(bool, bool)' does not exist

Unfortunately, it seems no one has bothered to create a functional form
of AND (the keyword-AND operator isn't a function).  I'll leave that
part as an exercise for the student ...
        regards, tom lane