52.56. `pg_trigger`
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## 52.56. `pg_trigger`

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

Table 52.56. `pg_trigger` Columns

Column Type Description
`oid` `oid` Row identifier
`tgrelid` `oid` (references `pg_class`.`oid`) The table this trigger is on
`tgparentid` `oid` (references `pg_trigger`.`oid`) Parent trigger that this trigger is cloned from (this happens when partitions are created or attached to a partitioned table); zero if not a clone
`tgname` `name` Trigger name (must be unique among triggers of same table)
`tgfoid` `oid` (references `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` (references `pg_class`.`oid`) The table referenced by a referential integrity constraint (zero if trigger is not for a referential integrity constraint)
`tgconstrindid` `oid` (references `pg_class`.`oid`) The index supporting a unique, primary key, referential integrity, or exclusion constraint (zero if trigger is not for one of these types of constraint)
`tgconstraint` `oid` (references `pg_constraint`.`oid`) The `pg_constraint` entry associated with the trigger (zero if trigger is not for a constraint)
`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` (references `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.

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