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-rw-r--r--doc/src/sgml/event-trigger.sgml110
-rw-r--r--doc/src/sgml/func.sgml113
2 files changed, 218 insertions, 5 deletions
diff --git a/doc/src/sgml/event-trigger.sgml b/doc/src/sgml/event-trigger.sgml
index 71241c82245..36928413d15 100644
--- a/doc/src/sgml/event-trigger.sgml
+++ b/doc/src/sgml/event-trigger.sgml
@@ -27,17 +27,19 @@
<para>
An event trigger fires whenever the event with which it is associated
occurs in the database in which it is defined. Currently, the only
- supported events are <literal>ddl_command_start</>
- and <literal>ddl_command_end</>. Support for additional events may be
- added in future releases.
+ supported events are
+ <literal>ddl_command_start</>,
+ <literal>ddl_command_end</>
+ and <literal>sql_drop</>.
+ Support for additional events may be added in future releases.
</para>
<para>
The <literal>ddl_command_start</> event occurs just before the
execution of a <literal>CREATE</>, <literal>ALTER</>, or <literal>DROP</>
command. As an exception, however, this event does not occur for
- DDL commands targeting shared objects - databases, roles, and tablespaces
- - or for command targeting event triggers themselves. The event trigger
+ DDL commands targeting shared objects &mdash; databases, roles, and tablespaces
+ &mdash; or for command targeting event triggers themselves. The event trigger
mechanism does not support these object types.
<literal>ddl_command_start</> also occurs just before the execution of a
<literal>SELECT INTO</literal> command, since this is equivalent to
@@ -46,6 +48,17 @@
</para>
<para>
+ The <literal>sql_drop</> event occurs just before the
+ <literal>ddl_command_end</> event trigger for any operation that drops
+ database objects. To list the objects that have been dropped, use the set
+ returning function <literal>pg_event_trigger_dropped_objects()</> from your
+ <literal>sql_drop</> event trigger code (see
+ <xref linkend="functions-event-triggers">). Note that
+ the trigger is executed after the objects have been deleted from the
+ system catalogs, so it's not possible to look them up anymore.
+ </para>
+
+ <para>
Event triggers (like other functions) cannot be executed in an aborted
transaction. Thus, if a DDL command fails with an error, any associated
<literal>ddl_command_end</> triggers will not be executed. Conversely,
@@ -99,6 +112,7 @@
<entry>command tag</entry>
<entry><literal>ddl_command_start</literal></entry>
<entry><literal>ddl_command_end</literal></entry>
+ <entry><literal>sql_drop</literal></entry>
</row>
</thead>
<tbody>
@@ -106,401 +120,487 @@
<entry align="left"><literal>ALTER AGGREGATE</literal></entry>
<entry align="center"><literal>X</literal></entry>
<entry align="center"><literal>X</literal></entry>
+ <entry align="center"><literal>-</literal></entry>
</row>
<row>
<entry align="left"><literal>ALTER COLLATION</literal></entry>
<entry align="center"><literal>X</literal></entry>
<entry align="center"><literal>X</literal></entry>
+ <entry align="center"><literal>-</literal></entry>
</row>
<row>
<entry align="left"><literal>ALTER CONVERSION</literal></entry>
<entry align="center"><literal>X</literal></entry>
<entry align="center"><literal>X</literal></entry>
+ <entry align="center"><literal>-</literal></entry>
</row>
<row>
<entry align="left"><literal>ALTER DOMAIN</literal></entry>
<entry align="center"><literal>X</literal></entry>
<entry align="center"><literal>X</literal></entry>
+ <entry align="center"><literal>-</literal></entry>
</row>
<row>
<entry align="left"><literal>ALTER EXTENSION</literal></entry>
<entry align="center"><literal>X</literal></entry>
<entry align="center"><literal>X</literal></entry>
+ <entry align="center"><literal>-</literal></entry>
</row>
<row>
<entry align="left"><literal>ALTER FOREIGN DATA WRAPPER</literal></entry>
<entry align="center"><literal>X</literal></entry>
<entry align="center"><literal>X</literal></entry>
+ <entry align="center"><literal>-</literal></entry>
</row>
<row>
<entry align="left"><literal>ALTER FOREIGN TABLE</literal></entry>
<entry align="center"><literal>X</literal></entry>
<entry align="center"><literal>X</literal></entry>
+ <entry align="center"><literal>X</literal></entry>
</row>
<row>
<entry align="left"><literal>ALTER FUNCTION</literal></entry>
<entry align="center"><literal>X</literal></entry>
<entry align="center"><literal>X</literal></entry>
+ <entry align="center"><literal>-</literal></entry>
</row>
<row>
<entry align="left"><literal>ALTER LANGUAGE</literal></entry>
<entry align="center"><literal>X</literal></entry>
<entry align="center"><literal>X</literal></entry>
+ <entry align="center"><literal>-</literal></entry>
</row>
<row>
<entry align="left"><literal>ALTER OPERATOR</literal></entry>
<entry align="center"><literal>X</literal></entry>
<entry align="center"><literal>X</literal></entry>
+ <entry align="center"><literal>-</literal></entry>
</row>
<row>
<entry align="left"><literal>ALTER OPERATOR CLASS</literal></entry>
<entry align="center"><literal>X</literal></entry>
<entry align="center"><literal>X</literal></entry>
+ <entry align="center"><literal>-</literal></entry>
</row>
<row>
<entry align="left"><literal>ALTER OPERATOR FAMILY</literal></entry>
<entry align="center"><literal>X</literal></entry>
<entry align="center"><literal>X</literal></entry>
+ <entry align="center"><literal>-</literal></entry>
</row>
<row>
<entry align="left"><literal>ALTER SCHEMA</literal></entry>
<entry align="center"><literal>X</literal></entry>
<entry align="center"><literal>X</literal></entry>
+ <entry align="center"><literal>-</literal></entry>
</row>
<row>
<entry align="left"><literal>ALTER SEQUENCE</literal></entry>
<entry align="center"><literal>X</literal></entry>
<entry align="center"><literal>X</literal></entry>
+ <entry align="center"><literal>-</literal></entry>
</row>
<row>
<entry align="left"><literal>ALTER SERVER</literal></entry>
<entry align="center"><literal>X</literal></entry>
<entry align="center"><literal>X</literal></entry>
+ <entry align="center"><literal>-</literal></entry>
</row>
<row>
<entry align="left"><literal>ALTER TABLE</literal></entry>
<entry align="center"><literal>X</literal></entry>
<entry align="center"><literal>X</literal></entry>
+ <entry align="center"><literal>X</literal></entry>
</row>
<row>
<entry align="left"><literal>ALTER TEXT SEARCH CONFIGURATION</literal></entry>
<entry align="center"><literal>X</literal></entry>
<entry align="center"><literal>X</literal></entry>
+ <entry align="center"><literal>-</literal></entry>
</row>
<row>
<entry align="left"><literal>ALTER TEXT SEARCH DICTIONARY</literal></entry>
<entry align="center"><literal>X</literal></entry>
<entry align="center"><literal>X</literal></entry>
+ <entry align="center"><literal>-</literal></entry>
</row>
<row>
<entry align="left"><literal>ALTER TEXT SEARCH PARSER</literal></entry>
<entry align="center"><literal>X</literal></entry>
<entry align="center"><literal>X</literal></entry>
+ <entry align="center"><literal>-</literal></entry>
</row>
<row>
<entry align="left"><literal>ALTER TEXT SEARCH TEMPLATE</literal></entry>
<entry align="center"><literal>X</literal></entry>
<entry align="center"><literal>X</literal></entry>
+ <entry align="center"><literal>-</literal></entry>
</row>
<row>
<entry align="left"><literal>ALTER TRIGGER</literal></entry>
<entry align="center"><literal>X</literal></entry>
<entry align="center"><literal>X</literal></entry>
+ <entry align="center"><literal>-</literal></entry>
</row>
<row>
<entry align="left"><literal>ALTER TYPE</literal></entry>
<entry align="center"><literal>X</literal></entry>
<entry align="center"><literal>X</literal></entry>
+ <entry align="center"><literal>-</literal></entry>
</row>
<row>
<entry align="left"><literal>ALTER USER MAPPING</literal></entry>
<entry align="center"><literal>X</literal></entry>
<entry align="center"><literal>X</literal></entry>
+ <entry align="center"><literal>-</literal></entry>
</row>
<row>
<entry align="left"><literal>ALTER VIEW</literal></entry>
<entry align="center"><literal>X</literal></entry>
<entry align="center"><literal>X</literal></entry>
+ <entry align="center"><literal>-</literal></entry>
</row>
<row>
<entry align="left"><literal>CREATE AGGREGATE</literal></entry>
<entry align="center"><literal>X</literal></entry>
<entry align="center"><literal>X</literal></entry>
+ <entry align="center"><literal>-</literal></entry>
</row>
<row>
<entry align="left"><literal>CREATE CAST</literal></entry>
<entry align="center"><literal>X</literal></entry>
<entry align="center"><literal>X</literal></entry>
+ <entry align="center"><literal>-</literal></entry>
</row>
<row>
<entry align="left"><literal>CREATE COLLATION</literal></entry>
<entry align="center"><literal>X</literal></entry>
<entry align="center"><literal>X</literal></entry>
+ <entry align="center"><literal>-</literal></entry>
</row>
<row>
<entry align="left"><literal>CREATE CONVERSION</literal></entry>
<entry align="center"><literal>X</literal></entry>
<entry align="center"><literal>X</literal></entry>
+ <entry align="center"><literal>-</literal></entry>
</row>
<row>
<entry align="left"><literal>CREATE DOMAIN</literal></entry>
<entry align="center"><literal>X</literal></entry>
<entry align="center"><literal>X</literal></entry>
+ <entry align="center"><literal>-</literal></entry>
</row>
<row>
<entry align="left"><literal>CREATE EXTENSION</literal></entry>
<entry align="center"><literal>X</literal></entry>
<entry align="center"><literal>X</literal></entry>
+ <entry align="center"><literal>-</literal></entry>
</row>
<row>
<entry align="left"><literal>CREATE FOREIGN DATA WRAPPER</literal></entry>
<entry align="center"><literal>X</literal></entry>
<entry align="center"><literal>X</literal></entry>
+ <entry align="center"><literal>-</literal></entry>
</row>
<row>
<entry align="left"><literal>CREATE FOREIGN TABLE</literal></entry>
<entry align="center"><literal>X</literal></entry>
<entry align="center"><literal>X</literal></entry>
+ <entry align="center"><literal>-</literal></entry>
</row>
<row>
<entry align="left"><literal>CREATE FUNCTION</literal></entry>
<entry align="center"><literal>X</literal></entry>
<entry align="center"><literal>X</literal></entry>
+ <entry align="center"><literal>-</literal></entry>
</row>
<row>
<entry align="left"><literal>CREATE INDEX</literal></entry>
<entry align="center"><literal>X</literal></entry>
<entry align="center"><literal>X</literal></entry>
+ <entry align="center"><literal>-</literal></entry>
</row>
<row>
<entry align="left"><literal>CREATE LANGUAGE</literal></entry>
<entry align="center"><literal>X</literal></entry>
<entry align="center"><literal>X</literal></entry>
+ <entry align="center"><literal>-</literal></entry>
</row>
<row>
<entry align="left"><literal>CREATE OPERATOR</literal></entry>
<entry align="center"><literal>X</literal></entry>
<entry align="center"><literal>X</literal></entry>
+ <entry align="center"><literal>-</literal></entry>
</row>
<row>
<entry align="left"><literal>CREATE OPERATOR CLASS</literal></entry>
<entry align="center"><literal>X</literal></entry>
<entry align="center"><literal>X</literal></entry>
+ <entry align="center"><literal>-</literal></entry>
</row>
<row>
<entry align="left"><literal>CREATE OPERATOR FAMILY</literal></entry>
<entry align="center"><literal>X</literal></entry>
<entry align="center"><literal>X</literal></entry>
+ <entry align="center"><literal>-</literal></entry>
</row>
<row>
<entry align="left"><literal>CREATE RULE</literal></entry>
<entry align="center"><literal>X</literal></entry>
<entry align="center"><literal>X</literal></entry>
+ <entry align="center"><literal>-</literal></entry>
</row>
<row>
<entry align="left"><literal>CREATE SCHEMA</literal></entry>
<entry align="center"><literal>X</literal></entry>
<entry align="center"><literal>X</literal></entry>
+ <entry align="center"><literal>-</literal></entry>
</row>
<row>
<entry align="left"><literal>CREATE SEQUENCE</literal></entry>
<entry align="center"><literal>X</literal></entry>
<entry align="center"><literal>X</literal></entry>
+ <entry align="center"><literal>-</literal></entry>
</row>
<row>
<entry align="left"><literal>CREATE SERVER</literal></entry>
<entry align="center"><literal>X</literal></entry>
<entry align="center"><literal>X</literal></entry>
+ <entry align="center"><literal>-</literal></entry>
</row>
<row>
<entry align="left"><literal>CREATE TABLE</literal></entry>
<entry align="center"><literal>X</literal></entry>
<entry align="center"><literal>X</literal></entry>
+ <entry align="center"><literal>-</literal></entry>
</row>
<row>
<entry align="left"><literal>CREATE TABLE AS</literal></entry>
<entry align="center"><literal>X</literal></entry>
<entry align="center"><literal>X</literal></entry>
+ <entry align="center"><literal>-</literal></entry>
</row>
<row>
<entry align="left"><literal>CREATE TEXT SEARCH CONFIGURATION</literal></entry>
<entry align="center"><literal>X</literal></entry>
<entry align="center"><literal>X</literal></entry>
+ <entry align="center"><literal>-</literal></entry>
</row>
<row>
<entry align="left"><literal>CREATE TEXT SEARCH DICTIONARY</literal></entry>
<entry align="center"><literal>X</literal></entry>
<entry align="center"><literal>X</literal></entry>
+ <entry align="center"><literal>-</literal></entry>
</row>
<row>
<entry align="left"><literal>CREATE TEXT SEARCH PARSER</literal></entry>
<entry align="center"><literal>X</literal></entry>
<entry align="center"><literal>X</literal></entry>
+ <entry align="center"><literal>-</literal></entry>
</row>
<row>
<entry align="left"><literal>CREATE TEXT SEARCH TEMPLATE</literal></entry>
<entry align="center"><literal>X</literal></entry>
<entry align="center"><literal>X</literal></entry>
+ <entry align="center"><literal>-</literal></entry>
</row>
<row>
<entry align="left"><literal>CREATE TRIGGER</literal></entry>
<entry align="center"><literal>X</literal></entry>
<entry align="center"><literal>X</literal></entry>
+ <entry align="center"><literal>-</literal></entry>
</row>
<row>
<entry align="left"><literal>CREATE TYPE</literal></entry>
<entry align="center"><literal>X</literal></entry>
<entry align="center"><literal>X</literal></entry>
+ <entry align="center"><literal>-</literal></entry>
</row>
<row>
<entry align="left"><literal>CREATE USER MAPPING</literal></entry>
<entry align="center"><literal>X</literal></entry>
<entry align="center"><literal>X</literal></entry>
+ <entry align="center"><literal>-</literal></entry>
</row>
<row>
<entry align="left"><literal>CREATE VIEW</literal></entry>
<entry align="center"><literal>X</literal></entry>
<entry align="center"><literal>X</literal></entry>
+ <entry align="center"><literal>-</literal></entry>
</row>
<row>
<entry align="left"><literal>DROP AGGREGATE</literal></entry>
<entry align="center"><literal>X</literal></entry>
<entry align="center"><literal>X</literal></entry>
+ <entry align="center"><literal>X</literal></entry>
</row>
<row>
<entry align="left"><literal>DROP CAST</literal></entry>
<entry align="center"><literal>X</literal></entry>
<entry align="center"><literal>X</literal></entry>
+ <entry align="center"><literal>X</literal></entry>
</row>
<row>
<entry align="left"><literal>DROP COLLATION</literal></entry>
<entry align="center"><literal>X</literal></entry>
<entry align="center"><literal>X</literal></entry>
+ <entry align="center"><literal>X</literal></entry>
</row>
<row>
<entry align="left"><literal>DROP CONVERSION</literal></entry>
<entry align="center"><literal>X</literal></entry>
<entry align="center"><literal>X</literal></entry>
+ <entry align="center"><literal>X</literal></entry>
</row>
<row>
<entry align="left"><literal>DROP DOMAIN</literal></entry>
<entry align="center"><literal>X</literal></entry>
<entry align="center"><literal>X</literal></entry>
+ <entry align="center"><literal>X</literal></entry>
</row>
<row>
<entry align="left"><literal>DROP EXTENSION</literal></entry>
<entry align="center"><literal>X</literal></entry>
<entry align="center"><literal>X</literal></entry>
+ <entry align="center"><literal>X</literal></entry>
</row>
<row>
<entry align="left"><literal>DROP FOREIGN DATA WRAPPER</literal></entry>
<entry align="center"><literal>X</literal></entry>
<entry align="center"><literal>X</literal></entry>
+ <entry align="center"><literal>X</literal></entry>
</row>
<row>
<entry align="left"><literal>DROP FOREIGN TABLE</literal></entry>
<entry align="center"><literal>X</literal></entry>
<entry align="center"><literal>X</literal></entry>
+ <entry align="center"><literal>X</literal></entry>
</row>
<row>
<entry align="left"><literal>DROP FUNCTION</literal></entry>
<entry align="center"><literal>X</literal></entry>
<entry align="center"><literal>X</literal></entry>
+ <entry align="center"><literal>X</literal></entry>
</row>
<row>
<entry align="left"><literal>DROP INDEX</literal></entry>
<entry align="center"><literal>X</literal></entry>
<entry align="center"><literal>X</literal></entry>
+ <entry align="center"><literal>X</literal></entry>
</row>
<row>
<entry align="left"><literal>DROP LANGUAGE</literal></entry>
<entry align="center"><literal>X</literal></entry>
<entry align="center"><literal>X</literal></entry>
+ <entry align="center"><literal>X</literal></entry>
</row>
<row>
<entry align="left"><literal>DROP OPERATOR</literal></entry>
<entry align="center"><literal>X</literal></entry>
<entry align="center"><literal>X</literal></entry>
+ <entry align="center"><literal>X</literal></entry>
</row>
<row>
<entry align="left"><literal>DROP OPERATOR CLASS</literal></entry>
<entry align="center"><literal>X</literal></entry>
<entry align="center"><literal>X</literal></entry>
+ <entry align="center"><literal>X</literal></entry>
</row>
<row>
<entry align="left"><literal>DROP OPERATOR FAMILY</literal></entry>
<entry align="center"><literal>X</literal></entry>
<entry align="center"><literal>X</literal></entry>
+ <entry align="center"><literal>X</literal></entry>
+ </row>
+ <row>
+ <entry align="left"><literal>DROP OWNED</literal></entry>
+ <entry align="center"><literal>X</literal></entry>
+ <entry align="center"><literal>X</literal></entry>
+ <entry align="center"><literal>X</literal></entry>
</row>
<row>
<entry align="left"><literal>DROP RULE</literal></entry>
<entry align="center"><literal>X</literal></entry>
<entry align="center"><literal>X</literal></entry>
+ <entry align="center"><literal>X</literal></entry>
</row>
<row>
<entry align="left"><literal>DROP SCHEMA</literal></entry>
<entry align="center"><literal>X</literal></entry>
<entry align="center"><literal>X</literal></entry>
+ <entry align="center"><literal>X</literal></entry>
</row>
<row>
<entry align="left"><literal>DROP SEQUENCE</literal></entry>
<entry align="center"><literal>X</literal></entry>
<entry align="center"><literal>X</literal></entry>
+ <entry align="center"><literal>X</literal></entry>
</row>
<row>
<entry align="left"><literal>DROP SERVER</literal></entry>
<entry align="center"><literal>X</literal></entry>
<entry align="center"><literal>X</literal></entry>
+ <entry align="center"><literal>X</literal></entry>
</row>
<row>
<entry align="left"><literal>DROP TABLE</literal></entry>
<entry align="center"><literal>X</literal></entry>
<entry align="center"><literal>X</literal></entry>
+ <entry align="center"><literal>X</literal></entry>
</row>
<row>
<entry align="left"><literal>DROP TEXT SEARCH CONFIGURATION</literal></entry>
<entry align="center"><literal>X</literal></entry>
<entry align="center"><literal>X</literal></entry>
+ <entry align="center"><literal>X</literal></entry>
</row>
<row>
<entry align="left"><literal>DROP TEXT SEARCH DICTIONARY</literal></entry>
<entry align="center"><literal>X</literal></entry>
<entry align="center"><literal>X</literal></entry>
+ <entry align="center"><literal>X</literal></entry>
</row>
<row>
<entry align="left"><literal>DROP TEXT SEARCH PARSER</literal></entry>
<entry align="center"><literal>X</literal></entry>
<entry align="center"><literal>X</literal></entry>
+ <entry align="center"><literal>X</literal></entry>
</row>
<row>
<entry align="left"><literal>DROP TEXT SEARCH TEMPLATE</literal></entry>
<entry align="center"><literal>X</literal></entry>
<entry align="center"><literal>X</literal></entry>
+ <entry align="center"><literal>X</literal></entry>
</row>
<row>
<entry align="left"><literal>DROP TRIGGER</literal></entry>
<entry align="center"><literal>X</literal></entry>
<entry align="center"><literal>X</literal></entry>
+ <entry align="center"><literal>X</literal></entry>
</row>
<row>
<entry align="left"><literal>DROP TYPE</literal></entry>
<entry align="center"><literal>X</literal></entry>
<entry align="center"><literal>X</literal></entry>
+ <entry align="center"><literal>X</literal></entry>
</row>
<row>
<entry align="left"><literal>DROP USER MAPPING</literal></entry>
<entry align="center"><literal>X</literal></entry>
<entry align="center"><literal>X</literal></entry>
+ <entry align="center"><literal>X</literal></entry>
</row>
<row>
<entry align="left"><literal>DROP VIEW</literal></entry>
<entry align="center"><literal>X</literal></entry>
<entry align="center"><literal>X</literal></entry>
+ <entry align="center"><literal>X</literal></entry>
</row>
<row>
<entry align="left"><literal>SELECT INTO</literal></entry>
<entry align="center"><literal>X</literal></entry>
<entry align="center"><literal>X</literal></entry>
+ <entry align="center"><literal>-</literal></entry>
</row>
</tbody>
</tgroup>
diff --git a/doc/src/sgml/func.sgml b/doc/src/sgml/func.sgml
index 490d7106435..db4e33f871d 100644
--- a/doc/src/sgml/func.sgml
+++ b/doc/src/sgml/func.sgml
@@ -15980,4 +15980,117 @@ FOR EACH ROW EXECUTE PROCEDURE suppress_redundant_updates_trigger();
<xref linkend="SQL-CREATETRIGGER">.
</para>
</sect1>
+
+ <sect1 id="functions-event-triggers">
+ <title>Event Trigger Functions</title>
+
+ <indexterm>
+ <primary>pg_event_trigger_dropped_objects</primary>
+ </indexterm>
+
+ <para>
+ Currently <productname>PostgreSQL</> provides one built-in event trigger
+ helper function, <function>pg_event_trigger_dropped_objects</>.
+ </para>
+
+ <para>
+ <function>pg_event_trigger_dropped_objects</> returns a list of all object
+ dropped by the command in whose <literal>sql_drop</> event it is called.
+ If called in any other context,
+ <function>pg_event_trigger_dropped_objects</> raises an error.
+ <function>pg_event_trigger_dropped_objects</> returns the following columns:
+
+ <informaltable>
+ <tgroup cols="3">
+ <thead>
+ <row>
+ <entry>Name</entry>
+ <entry>Type</entry>
+ <entry>Description</entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry><literal>classid</literal></entry>
+ <entry><type>Oid</type></entry>
+ <entry>OID of catalog the object belonged in</entry>
+ </row>
+ <row>
+ <entry><literal>objid</literal></entry>
+ <entry><type>Oid</type></entry>
+ <entry>OID the object had within the catalog</entry>
+ </row>
+ <row>
+ <entry><literal>objsubid</literal></entry>
+ <entry><type>int32</type></entry>
+ <entry>Object sub-id (e.g. attribute number for columns)</entry>
+ </row>
+ <row>
+ <entry><literal>object_type</literal></entry>
+ <entry><type>text</type></entry>
+ <entry>Type of the object</entry>
+ </row>
+ <row>
+ <entry><literal>schema_name</literal></entry>
+ <entry><type>text</type></entry>
+ <entry>
+ Name of the schema the object belonged in, if any; otherwise <literal>NULL</>.
+ No quoting is applied.
+ </entry>
+ </row>
+ <row>
+ <entry><literal>object_name</literal></entry>
+ <entry><type>text</type></entry>
+ <entry>
+ Name of the object, if the combination of schema and name can be
+ used as an unique identifier for the object; otherwise <literal>NULL</>.
+ No quoting is applied, and name is never schema-qualified.
+ </entry>
+ </row>
+ <row>
+ <entry><literal>object_identity</literal></entry>
+ <entry><type>text</type></entry>
+ <entry>
+ Text rendering of the object identity, schema-qualified. Each and every
+ identifier present in the identity is quoted if necessary.
+ </entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </informaltable>
+ </para>
+
+ <para>
+ The <function>pg_event_trigger_dropped_objects</> function can be used
+ in an event trigger like this:
+<programlisting>
+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 PROCEDURE test_event_trigger_for_drops();
+</programlisting>
+ </para>
+
+ <para>
+ For more information about event triggers,
+ see <xref linkend="event-triggers">.
+ </para>
+ </sect1>
+
</chapter>