PostgreSQL provides these helper functions to retrieve information from event triggers.
For more information about event triggers, see 39장.
pg_event_trigger_ddl_commands
() →setof record
pg_event_trigger_ddl_commands
returns a list of
DDL commands executed by each user action,
when invoked in a function attached to a
ddl_command_end
event trigger. If called in any other
context, an error is raised.
pg_event_trigger_ddl_commands
returns one row for each
base command executed; some commands that are a single SQL sentence
may return more than one row. This function returns the following
columns:
Name | Type | Description |
---|---|---|
classid | oid | OID of catalog the object belongs in |
objid | oid | OID of the object itself |
objsubid | integer | Sub-object ID (e.g., attribute number for a column) |
command_tag | text | Command tag |
object_type | text | Type of the object |
schema_name | text |
Name of the schema the object belongs in, if any; otherwise NULL .
No quoting is applied.
|
object_identity | text | Text rendering of the object identity, schema-qualified. Each identifier included in the identity is quoted if necessary. |
in_extension | boolean | True if the command is part of an extension script |
command | pg_ddl_command | A complete representation of the command, in internal format. This cannot be output directly, but it can be passed to other functions to obtain different pieces of information about the command. |
pg_event_trigger_dropped_objects
() →setof record
pg_event_trigger_dropped_objects
returns a list of all objects
dropped by the command in whose sql_drop
event it is called.
If called in any other context, an error is raised.
This function returns the following columns:
Name | Type | Description |
---|---|---|
classid | oid | OID of catalog the object belonged in |
objid | oid | OID of the object itself |
objsubid | integer | Sub-object ID (e.g., attribute number for a column) |
original | boolean | True if this was one of the root object(s) of the deletion |
normal | boolean | True if there was a normal dependency relationship in the dependency graph leading to this object |
is_temporary | boolean | True if this was a temporary object |
object_type | text | Type of the object |
schema_name | text |
Name of the schema the object belonged in, if any; otherwise NULL .
No quoting is applied.
|
object_name | text |
Name of the object, if the combination of schema and name can be
used as a unique identifier for the object; otherwise NULL .
No quoting is applied, and name is never schema-qualified.
|
object_identity | text | Text rendering of the object identity, schema-qualified. Each identifier included in the identity is quoted if necessary. |
address_names | text[] |
An array that, together with object_type and
address_args , can be used by
the pg_get_object_address function to
recreate the object address in a remote server containing an
identically named object of the same kind.
|
address_args | text[] |
Complement for address_names
|
The pg_event_trigger_dropped_objects
function can be used
in an event trigger like this:
CREATE FUNCTION test_event_trigger_for_drops() RETURNS event_trigger LANGUAGE plpgsql AS $$ DECLARE obj record; BEGIN FOR obj IN SELECT * FROM pg_event_trigger_dropped_objects() LOOP RAISE NOTICE '% dropped object: % %.% %', tg_tag, obj.object_type, obj.schema_name, obj.object_name, obj.object_identity; END LOOP; END; $$; CREATE EVENT TRIGGER test_event_trigger_for_drops ON sql_drop EXECUTE FUNCTION test_event_trigger_for_drops();
The functions shown in
표 9.98
provide information about a table for which a
table_rewrite
event has just been called.
If called in any other context, an error is raised.
표 9.98. Table Rewrite Information Functions
These functions can be used in an event trigger like this:
CREATE FUNCTION test_event_trigger_table_rewrite_oid() RETURNS event_trigger LANGUAGE plpgsql AS $$ BEGIN RAISE NOTICE 'rewriting table % for reason %', pg_event_trigger_table_rewrite_oid()::regclass, pg_event_trigger_table_rewrite_reason(); END; $$; CREATE EVENT TRIGGER test_table_rewrite_oid ON table_rewrite EXECUTE FUNCTION test_event_trigger_table_rewrite_oid();