pg_aggregate

The pg_aggregate table stores information about aggregate functions. An aggregate function is a function that operates on a set of values (typically one column from each row that matches a query condition) and returns a single value computed from all these values. Typical aggregate functions are sum, count, and max. 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.

column	type	references	description
aggfnoid	regproc	pg_proc.oid	OID of the aggregate function
aggkind	char		Aggregate kind: n for normal aggregates, o for ordered-set aggregates, or h for hypothetical-set aggregates
aggnumdirectargs	smallint		Number of direct (non-aggregated) arguments of an ordered-set or hypothetical-set aggregate, counting a variadic array as one argument. If equal to pronargs, the aggregate must be variadic and the variadic array describes the aggregated arguments as well as the final direct arguments. Always zero for normal aggregates.
aggtransfn	regproc	pg_proc.oid	Transition function OID
aggfinalfn	regproc	pg_proc.oid	Final function OID (zero if none)
aggcombinefn	regproc	pg_proc.oid	Combine function OID (zero if none)
aggserialfn	regproc	pg_proc.oid	OID of the serialization function to convert transtype to bytea (zero if none)
aggdeserialfn	regproc	pg_proc.oid	OID of the deserialization function to convert bytea to transtype (zero if none)
aggmtransfn	regproc	pg_proc.oid	Forward transition function OID for moving-aggregate mode (zero if none)
aggminvtransfn	regproc	pg_proc.oid	Inverse transition function OID for moving-aggregate mode (zero if none)
aggmfinalfn	regproc	pg_proc.oid	Final function OID for moving-aggregate mode (zero if none)
aggfinalextra	bool		True to pass extra dummy arguments to aggfinalfn
aggmfinalextra	bool		True to pass extra dummy arguments to aggmfinalfn
aggfinalmodify	char		Indicates whether aggfinalfn modifies the transition state
aggmfinalmodify	char		Indicates whether aggmfinalfn modifies the transition state
aggsortop	oid	pg_operator.oid	Associated sort operator OID (zero if none)
aggtranstype	oid	pg_type.oid	Data type of the aggregate function's internal transition (state) data
aggtransspace	integer		Approximate average size (in bytes) of the transition state data, or zero to use a default estimate
aggmtranstype	oid	pg_type.oid	Data type of the aggregate function's internal transition (state) data for moving-aggregate mode (zero if none)
aggmtransspace	integer		Approximate average size (in bytes) of the transition state data for moving-aggregate mode, or zero to use a default estimate
agginitval	text		The initial value of the transition state. This is a text field containing the initial value in its external string representation. If this field is NULL, the transition state value starts out NULL.
aggminitval	text		The initial value of the transition state for moving- aggregate mode. This is a text field containing the initial value in its external string representation. If this field is NULL, the transition state value starts out NULL.
aggrepsafeexec	bool		True to specify that the aggregate can be safely executed on replicated slices. An order-agnostic aggregate would be considered safe in this context.

Parent topic: System Catalogs Definitions