51.56. pg_trigger

The catalog pg_trigger stores triggers on tables and views. See CREATE TRIGGER for more information.

Table 51.56. pg_trigger Columns

Name	Type	References	Description
oid	oid		Row identifier (hidden attribute; must be explicitly selected)
tgrelid	oid	pg_class.oid	The table this trigger is on
tgname	name		Trigger name (must be unique among triggers of same table)
tgfoid	oid	pg_proc.oid	The function to be called
tgtype	int2		Bit mask identifying trigger firing conditions
tgenabled	char		Controls in which session_replication_role modes the trigger fires. O = trigger fires in “origin” and “local” modes, D = trigger is disabled, R = trigger fires in “replica” mode, A = trigger fires always.
tgisinternal	bool		True if trigger is internally generated (usually, to enforce the constraint identified by tgconstraint)
tgconstrrelid	oid	pg_class.oid	The table referenced by a referential integrity constraint
tgconstrindid	oid	pg_class.oid	The index supporting a unique, primary key, referential integrity, or exclusion constraint
tgconstraint	oid	pg_constraint.oid	The pg_constraint entry associated with the trigger, if any
tgdeferrable	bool		True if constraint trigger is deferrable
tginitdeferred	bool		True if constraint trigger is initially deferred
tgnargs	int2		Number of argument strings passed to trigger function
tgattr	int2vector	pg_attribute.attnum	Column numbers, if trigger is column-specific; otherwise an empty array
tgargs	bytea		Argument strings to pass to trigger, each NULL-terminated
tgqual	pg_node_tree		Expression tree (in nodeToString() representation) for the trigger's WHEN condition, or null if none
tgoldtable	name		REFERENCING clause name for OLD TABLE, or null if none
tgnewtable	name		REFERENCING clause name for NEW TABLE, or null if none

Currently, column-specific triggering is supported only for UPDATE events, and so tgattr is relevant only for that event type. tgtype might contain bits for other event types as well, but those are presumed to be table-wide regardless of what is in tgattr.

Note

When tgconstraint is nonzero, tgconstrrelid, tgconstrindid, tgdeferrable, and tginitdeferred are largely redundant with the referenced pg_constraint entry. However, it is possible for a non-deferrable trigger to be associated with a deferrable constraint: foreign key constraints can have some deferrable and some non-deferrable triggers.

Note

pg_class.relhastriggers must be true if a relation has any triggers in this catalog.