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30.37. triggers
The view triggers contains all triggers defined in the current database that are owned by the current user. (The owner of the table is the owner of the trigger.)
Table 30-35. triggers Columns
| Name | Data 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_name | sql_identifier | Name of the table that the trigger is defined on |
| action_order | cardinal_number | Not yet implemented |
| action_condition | character_data | Applies to a feature not available in PostgreSQL |
| action_statement | character_data | Statement that is executed by the trigger (currently always EXECUTE PROCEDURE function(...)) |
| action_orientation | character_data | Identifies whether the trigger fires once for each processed row or once for each statement (ROW or STATEMENT) |
| condition_timing | character_data | Time at which the trigger fires (BEFORE or AFTER) |
| condition_reference_old_table | sql_identifier | Applies to a feature not available in PostgreSQL |
| condition_reference_new_table | sql_identifier | 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 the table in PostgreSQL, rather than being independent schema objects. Therefore there may be duplicate trigger names defined in one schema, as 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, trigger_name, event_object_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.
