38.57. triggers

38.57. `triggers`
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38.57. `triggers`

The view triggers contains all triggers defined in the current database on tables and views that the current user owns or has some privilege other than SELECT on.

Table 38.55. triggers Columns

Column Type Description
`trigger_catalog` `sql_identifier` Name of the database that contains the trigger (always the current database)
`trigger_schema` `sql_identifier` Name of the schema that contains the trigger
`trigger_name` `sql_identifier` Name of the trigger
`event_manipulation` `character_data` Event that fires the trigger (`INSERT`, `UPDATE`, or `DELETE`)
`event_object_catalog` `sql_identifier` Name of the database that contains the table that the trigger is defined on (always the current database)
`event_object_schema` `sql_identifier` Name of the schema that contains the table that the trigger is defined on
`event_object_table` `sql_identifier` Name of the table that the trigger is defined on
`action_order` `cardinal_number` Firing order among triggers on the same table having the same `event_manipulation`, `action_timing`, and `action_orientation`. In PostgreSQL, triggers are fired in name order, so this column reflects that.
`action_condition` `character_data` `WHEN` condition of the trigger, null if none (also null if the table is not owned by a currently enabled role)
`action_statement` `character_data` Statement that is executed by the trigger (currently always `EXECUTE FUNCTION function(...)`)
`action_orientation` `character_data` Identifies whether the trigger fires once for each processed row or once for each statement (`ROW` or `STATEMENT`)
`action_timing` `character_data` Time at which the trigger fires (`BEFORE`, `AFTER`, or `INSTEAD OF`)
`action_reference_old_table` `sql_identifier` Name of the “old” transition table, or null if none
`action_reference_new_table` `sql_identifier` Name of the “new” transition table, or null if none
`action_reference_old_row` `sql_identifier` Applies to a feature not available in PostgreSQL
`action_reference_new_row` `sql_identifier` Applies to a feature not available in PostgreSQL
`created` `time_stamp` Applies to a feature not available in PostgreSQL

Column Type

Description

trigger_catalog sql_identifier

Name of the database that contains the trigger (always the current database)

trigger_schema sql_identifier

Name of the schema that contains the trigger

trigger_name sql_identifier

Name of the trigger

event_manipulation character_data

Event that fires the trigger (INSERT, UPDATE, or DELETE)

event_object_catalog sql_identifier

Name of the database that contains the table that the trigger is defined on (always the current database)

event_object_schema sql_identifier

Name of the schema that contains the table that the trigger is defined on

event_object_table sql_identifier

Name of the table that the trigger is defined on

action_order cardinal_number

Firing order among triggers on the same table having the same event_manipulation, action_timing, and action_orientation. In PostgreSQL, triggers are fired in name order, so this column reflects that.

action_condition character_data

WHEN condition of the trigger, null if none (also null if the table is not owned by a currently enabled role)

action_statement character_data

Statement that is executed by the trigger (currently always EXECUTE FUNCTION function(...))

action_orientation character_data

Identifies whether the trigger fires once for each processed row or once for each statement (ROW or STATEMENT)

action_timing character_data

Time at which the trigger fires (BEFORE, AFTER, or INSTEAD OF)

action_reference_old_table sql_identifier

Name of the “old” transition table, or null if none

action_reference_new_table sql_identifier

Name of the “new” transition table, or null if none

action_reference_old_row sql_identifier

Applies to a feature not available in PostgreSQL

action_reference_new_row sql_identifier

Applies to a feature not available in PostgreSQL

created time_stamp

Applies to a feature not available in PostgreSQL

Triggers in PostgreSQL have two incompatibilities with the SQL standard that affect the representation in the information schema. First, trigger names are local to each table in PostgreSQL, rather than being independent schema objects. Therefore there can be duplicate trigger names defined in one schema, so long as they belong to different tables. (trigger_catalog and trigger_schema are really the values pertaining to the table that the trigger is defined on.) Second, triggers can be defined to fire on multiple events in PostgreSQL (e.g., ON INSERT OR UPDATE), whereas the SQL standard only allows one. If a trigger is defined to fire on multiple events, it is represented as multiple rows in the information schema, one for each type of event. As a consequence of these two issues, the primary key of the view triggers is really (trigger_catalog, trigger_schema, event_object_table, trigger_name, event_manipulation) instead of (trigger_catalog, trigger_schema, trigger_name), which is what the SQL standard specifies. Nonetheless, if you define your triggers in a manner that conforms with the SQL standard (trigger names unique in the schema and only one event type per trigger), this will not affect you.

Note

Prior to PostgreSQL 9.1, this view's columns action_timing, action_reference_old_table, action_reference_new_table, action_reference_old_row, and action_reference_new_row were named condition_timing, condition_reference_old_table, condition_reference_new_table, condition_reference_old_row, and condition_reference_new_row respectively. That was how they were named in the SQL:1999 standard. The new naming conforms to SQL:2003 and later.

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