Merge pull request #5835 from citusdata/velioglu/poly_aggregate

Add support for zero-argument polymorphic aggregates

src/backend/distributed/commands/function.c

@@ -966,6 +966,14 @@ GetAggregateDDLCommand(const RegProcedure funcOid, bool useCreateOrReplace)
 		insertorderbyat = agg->aggnumdirectargs;
 	}
 
+	/*
+	 * For zero-argument aggregate, write * in place of the list of arguments
+	 */
+	if (numargs == 0)
+	{
+		appendStringInfo(&buf, "*");
+	}
+
 	for (i = 0; i < numargs; i++)
 	{
 		Oid argtype = argtypes[i];

src/test/regress/expected/aggregate_support.out

@@ -1189,6 +1189,28 @@ DROP TABLE dummy_tbl CASCADE;
 NOTICE:  drop cascades to 2 other objects
 DETAIL:  drop cascades to function dummy_fnc(dummy_tbl,double precision)
 drop cascades to function dependent_agg(double precision)
+-- Show that polymorphic aggregates with zero-argument works
+CREATE FUNCTION stfnp_zero_arg(int[]) RETURNS int[] AS
+'select $1' LANGUAGE SQL;
+CREATE FUNCTION ffp_zero_arg(anyarray) RETURNS anyarray AS
+'select $1' LANGUAGE SQL;
+CREATE AGGREGATE zero_arg_agg(*) (SFUNC = stfnp_zero_arg, STYPE = int4[],
+  FINALFUNC = ffp_zero_arg, INITCOND = '{}');
+CREATE TABLE zero_arg_agg_table(f1 int, f2 int[]);
+SELECT create_distributed_table('zero_arg_agg_table','f1');
+ create_distributed_table
+---------------------------------------------------------------------
+
+(1 row)
+
+INSERT INTO zero_arg_agg_table VALUES(1, array[1]);
+INSERT INTO zero_arg_agg_table VALUES(1, array[11]);
+SELECT zero_arg_agg(*) from zero_arg_agg_table;
+ zero_arg_agg
+---------------------------------------------------------------------
+ {}
+(1 row)
+
 -- Show that after dropping a table on which functions and aggregates depending on
 -- pg_dist_object is consistent on coordinator and worker node.
 SELECT pg_identify_object_as_address(classid, objid, objsubid)::text

src/test/regress/sql/aggregate_support.sql

@@ -603,6 +603,23 @@ SELECT run_command_on_workers($$select aggfnoid from pg_aggregate where aggfnoid
 
 DROP TABLE dummy_tbl CASCADE;
 
+-- Show that polymorphic aggregates with zero-argument works
+CREATE FUNCTION stfnp_zero_arg(int[]) RETURNS int[] AS
+'select $1' LANGUAGE SQL;
+
+CREATE FUNCTION ffp_zero_arg(anyarray) RETURNS anyarray AS
+'select $1' LANGUAGE SQL;
+
+CREATE AGGREGATE zero_arg_agg(*) (SFUNC = stfnp_zero_arg, STYPE = int4[],
+  FINALFUNC = ffp_zero_arg, INITCOND = '{}');
+
+CREATE TABLE zero_arg_agg_table(f1 int, f2 int[]);
+SELECT create_distributed_table('zero_arg_agg_table','f1');
+INSERT INTO zero_arg_agg_table VALUES(1, array[1]);
+INSERT INTO zero_arg_agg_table VALUES(1, array[11]);
+
+SELECT zero_arg_agg(*) from zero_arg_agg_table;
+
 -- Show that after dropping a table on which functions and aggregates depending on
 -- pg_dist_object is consistent on coordinator and worker node.
 SELECT pg_identify_object_as_address(classid, objid, objsubid)::text