Omit support functions

For completeness, the preceding examples show all four support functions: INIT, ITER, COMBINE, and FINAL. Because SUMSQ is a simple aggregate, the examples could have omitted the INIT and FINAL functions. You could use the following commands to create the SSQ2 aggregate:

CREATE FUNCTION ssq2_iter (result float, opr float)
   RETURNING float;
   IF result IS NULL THEN
     LET result = (opr*opr);
   ELSE
     LET result = result + opr*opr;
   END IF
   RETURN result;
END FUNCTION;

CREATE FUNCTION ssq2_combine(partial1 float, partial2 float)
   RETURNING float;
   RETURN partial1 + partial2;
END FUNCTION;

CREATE AGGREGATE ssq2 WITH
   (ITER = ssq2_iter,
    COMBINE = ssq2_combine);