PG_AGGREGATE

PG_AGGREGATE records information about aggregate functions. Each entry in PG_AGGREGATE is an extension of an entry in PG_PROC. The PG_PROC entry carries the aggregate's name, input and output data types, and other information that is similar to ordinary functions.

**Table 1** PG_AGGREGATE columns
Name	Type	Reference	Description
aggfnoid	regproc	proname in PG_PROC	PG_PROC proname of the aggregate function.
aggtransfn	regproc	proname in PG_PROC	Transition function.
aggcollectfn	regproc	proname in PG_PROC	Collect function.
aggfinalfn	regproc	proname in PG_PROC	Final function (0 if none).
aggsortop	oid	oid in PG_OPERATOR	Associated sort operator (0 if none).
aggtranstype	oid	oid in PG_TYPE	Data type of the aggregate function's internal transition (state) data. The possible values and their meanings are defined by the types in pg_type.h. The main two types are polymorphic (isPolymorphicType) and non-polymorphic.
agginitval	text	-	Initial value of the transition state. This is a text column containing the initial value in its external string representation. If this column is null, the transition state value starts from null.
agginitcollect	text	-	Initial value of the collection state. This is a text column containing the initial value in its external string representation. If this column is null, the collection state value starts from null.
aggkind	"char"	-	Type of the aggregate function: n: normal aggregate. o: ordered set aggregate.
aggnumdirectargs	smallint	-	Number of direct parameters (non-aggregation-related parameters) of the aggregate function of the ordered set aggregate type. For an aggregate function of the normal aggregate type, the value is 0.