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.