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 31-35. 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_table | 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_table, 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.