pg_event_trigger_dropped_objects: add behavior flags

Add "normal" and "original" flags as output columns to the
pg_event_trigger_dropped_objects() function.  With this it's possible to
distinguish which objects, among those listed, need to be explicitely
referenced when trying to replicate a deletion.

This is necessary so that the list of objects can be pruned to the
minimum necessary to replicate the DROP command in a remote server that
might have slightly different schema (for instance, TOAST tables and
constraints with different names and such.)

Catalog version bumped due to change of function definition.

Reviewed by: Abhijit Menon-Sen, Stephen Frost, Heikki Linnakangas,
Robert Haas.

doc/src/sgml/func.sgml

@@ -17729,6 +17729,19 @@ FOR EACH ROW EXECUTE PROCEDURE suppress_redundant_updates_trigger();
         <entry><type>int32</type></entry>
         <entry>Object sub-id (e.g. attribute number for columns)</entry>
        </row>
+       <row>
+        <entry><literal>original</literal></entry>
+        <entry><type>bool</type></entry>
+        <entry>Flag used to identify the root object(s) of the deletion</entry>
+       </row>
+       <row>
+        <entry><literal>normal</literal></entry>
+        <entry><type>bool</type></entry>
+        <entry>
+         Flag indicating that there's a normal dependency relationship
+         in the dependency graph leading to this object
+        </entry>
+       </row>
        <row>
         <entry><literal>object_type</literal></entry>
         <entry><type>text</type></entry>

src/backend/catalog/dependency.c

@@ -206,16 +206,25 @@ deleteObjectsInList(ObjectAddresses *targetObjects, Relation *depRel,
 	/*
 	 * Keep track of objects for event triggers, if necessary.
 	 */
-	if (trackDroppedObjectsNeeded())
+	if (trackDroppedObjectsNeeded() && !(flags & PERFORM_DELETION_INTERNAL))
 	{
 		for (i = 0; i < targetObjects->numrefs; i++)
 		{
-			ObjectAddress *thisobj = targetObjects->refs + i;
+			const ObjectAddress *thisobj = &targetObjects->refs[i];
+			const ObjectAddressExtra *extra = &targetObjects->extras[i];
+			bool	original = false;
+			bool	normal = false;
+
+			if (extra->flags & DEPFLAG_ORIGINAL)
+				original = true;
+			if (extra->flags & DEPFLAG_NORMAL)
+				normal = true;
+			if (extra->flags & DEPFLAG_REVERSE)
+				normal = true;
 
-			if ((!(flags & PERFORM_DELETION_INTERNAL)) &&
-				EventTriggerSupportsObjectClass(getObjectClass(thisobj)))
+			if (EventTriggerSupportsObjectClass(getObjectClass(thisobj)))
 			{
-				EventTriggerSQLDropAddObject(thisobj);
+				EventTriggerSQLDropAddObject(thisobj, original, normal);
 			}
 		}
 	}

src/backend/commands/event_trigger.c

@@ -117,6 +117,8 @@ typedef struct SQLDropObject
 	const char *objname;
 	const char *objidentity;
 	const char *objecttype;
+	bool		original;
+	bool		normal;
 	slist_node	next;
 } SQLDropObject;
 
@@ -1238,7 +1240,7 @@ trackDroppedObjectsNeeded(void)
  * Register one object as being dropped by the current command.
  */
 void
-EventTriggerSQLDropAddObject(ObjectAddress *object)
+EventTriggerSQLDropAddObject(const ObjectAddress *object, bool original, bool normal)
 {
 	SQLDropObject *obj;
 	MemoryContext oldcxt;
@@ -1257,6 +1259,8 @@ EventTriggerSQLDropAddObject(ObjectAddress *object)
 
 	obj = palloc0(sizeof(SQLDropObject));
 	obj->address = *object;
+	obj->original = original;
+	obj->normal = normal;
 
 	/*
 	 * Obtain schema names from the object's catalog tuple, if one exists;
@@ -1384,8 +1388,8 @@ pg_event_trigger_dropped_objects(PG_FUNCTION_ARGS)
 	{
 		SQLDropObject *obj;
 		int			i = 0;
-		Datum		values[7];
-		bool		nulls[7];
+		Datum		values[9];
+		bool		nulls[9];
 
 		obj = slist_container(SQLDropObject, next, iter.cur);
 
@@ -1401,6 +1405,12 @@ pg_event_trigger_dropped_objects(PG_FUNCTION_ARGS)
 		/* objsubid */
 		values[i++] = Int32GetDatum(obj->address.objectSubId);
 
+		/* original */
+		values[i++] = BoolGetDatum(obj->original);
+
+		/* normal */
+		values[i++] = BoolGetDatum(obj->normal);
+
 		/* object_type */
 		values[i++] = CStringGetTextDatum(obj->objecttype);
 

src/include/catalog/catversion.h

@@ -53,6 +53,6 @@
  */
 
 /*							yyyymmddN */
-#define CATALOG_VERSION_NO	201412122
+#define CATALOG_VERSION_NO	201412191
 
 #endif

src/include/catalog/pg_proc.h

@@ -5075,7 +5075,7 @@ DATA(insert OID = 3785 (  pg_logical_slot_peek_binary_changes PGNSP PGUID 12 100
 DESCR("peek at binary changes from replication slot");
 
 /* event triggers */
-DATA(insert OID = 3566 (  pg_event_trigger_dropped_objects		PGNSP PGUID 12 10 100 0 0 f f f f t t s 0 0 2249 "" "{26,26,23,25,25,25,25}" "{o,o,o,o,o,o,o}" "{classid, objid, objsubid, object_type, schema_name, object_name, object_identity}" _null_ pg_event_trigger_dropped_objects _null_ _null_ _null_ ));
+DATA(insert OID = 3566 (  pg_event_trigger_dropped_objects		PGNSP PGUID 12 10 100 0 0 f f f f t t s 0 0 2249 "" "{26,26,23,16,16,25,25,25,25}" "{o,o,o,o,o,o,o,o,o}" "{classid, objid, objsubid, original, normal, object_type, schema_name, object_name, object_identity}" _null_ pg_event_trigger_dropped_objects _null_ _null_ _null_ ));
 DESCR("list objects dropped by the current command");
 DATA(insert OID = 4566 (  pg_event_trigger_table_rewrite_oid	PGNSP PGUID 12 1 0 0 0 f f f f t f s 0 0 26 "" "{26}" "{o}" "{oid}" _null_ pg_event_trigger_table_rewrite_oid _null_ _null_ _null_ ));
 DESCR("return Oid of the table getting rewritten");

src/include/commands/event_trigger.h

@@ -56,6 +56,7 @@ extern void EventTriggerTableRewrite(Node *parsetree, Oid tableOid, int reason);
 extern bool EventTriggerBeginCompleteQuery(void);
 extern void EventTriggerEndCompleteQuery(void);
 extern bool trackDroppedObjectsNeeded(void);
-extern void EventTriggerSQLDropAddObject(ObjectAddress *object);
+extern void EventTriggerSQLDropAddObject(const ObjectAddress *object,
+							 bool original, bool normal);
 
 #endif   /* EVENT_TRIGGER_H */

src/test/regress/expected/event_trigger.out

@@ -294,6 +294,46 @@ SELECT * FROM dropped_objects WHERE type = 'schema';
 DROP ROLE regression_bob;
 DROP EVENT TRIGGER regress_event_trigger_drop_objects;
 DROP EVENT TRIGGER undroppable;
+CREATE OR REPLACE FUNCTION event_trigger_report_dropped()
+ RETURNS event_trigger
+ LANGUAGE plpgsql
+AS $$
+DECLARE r record;
+BEGIN
+    FOR r IN SELECT * from pg_event_trigger_dropped_objects()
+    LOOP
+    IF NOT r.normal AND NOT r.original THEN
+        CONTINUE;
+    END IF;
+    RAISE NOTICE 'NORMAL: orig=% normal=% type=% identity=%',
+        r.original, r.normal, r.object_type, r.object_identity;
+    END LOOP;
+END; $$;
+CREATE EVENT TRIGGER regress_event_trigger_report_dropped ON sql_drop
+    EXECUTE PROCEDURE event_trigger_report_dropped();
+CREATE SCHEMA evttrig
+	CREATE TABLE one (col_a SERIAL PRIMARY KEY, col_b text DEFAULT 'forty two')
+	CREATE INDEX one_idx ON one (col_b)
+	CREATE TABLE two (col_c INTEGER CHECK (col_c > 0) REFERENCES one DEFAULT 42);
+ALTER TABLE evttrig.two DROP COLUMN col_c;
+NOTICE:  NORMAL: orig=t normal=f type=table column identity=evttrig.two.col_c
+NOTICE:  NORMAL: orig=f normal=t type=table constraint identity=two_col_c_check on evttrig.two
+ALTER TABLE evttrig.one ALTER COLUMN col_b DROP DEFAULT;
+NOTICE:  NORMAL: orig=t normal=f type=default value identity=for evttrig.one.col_b
+ALTER TABLE evttrig.one DROP CONSTRAINT one_pkey;
+NOTICE:  NORMAL: orig=t normal=f type=table constraint identity=one_pkey on evttrig.one
+DROP INDEX evttrig.one_idx;
+NOTICE:  NORMAL: orig=t normal=f type=index identity=evttrig.one_idx
+DROP SCHEMA evttrig CASCADE;
+NOTICE:  drop cascades to 2 other objects
+DETAIL:  drop cascades to table evttrig.one
+drop cascades to table evttrig.two
+NOTICE:  NORMAL: orig=t normal=f type=schema identity=evttrig
+NOTICE:  NORMAL: orig=f normal=t type=table identity=evttrig.one
+NOTICE:  NORMAL: orig=f normal=t type=sequence identity=evttrig.one_col_a_seq
+NOTICE:  NORMAL: orig=f normal=t type=default value identity=for evttrig.one.col_a
+NOTICE:  NORMAL: orig=f normal=t type=table identity=evttrig.two
+DROP EVENT TRIGGER regress_event_trigger_report_dropped;
 -- only allowed from within an event trigger function, should fail
 select pg_event_trigger_table_rewrite_oid();
 ERROR:  pg_event_trigger_table_rewrite_oid() can only be called in a table_rewrite event trigger function

src/test/regress/sql/event_trigger.sql

@@ -207,6 +207,36 @@ DROP ROLE regression_bob;
 DROP EVENT TRIGGER regress_event_trigger_drop_objects;
 DROP EVENT TRIGGER undroppable;
 
+CREATE OR REPLACE FUNCTION event_trigger_report_dropped()
+ RETURNS event_trigger
+ LANGUAGE plpgsql
+AS $$
+DECLARE r record;
+BEGIN
+    FOR r IN SELECT * from pg_event_trigger_dropped_objects()
+    LOOP
+    IF NOT r.normal AND NOT r.original THEN
+        CONTINUE;
+    END IF;
+    RAISE NOTICE 'NORMAL: orig=% normal=% type=% identity=%',
+        r.original, r.normal, r.object_type, r.object_identity;
+    END LOOP;
+END; $$;
+CREATE EVENT TRIGGER regress_event_trigger_report_dropped ON sql_drop
+    EXECUTE PROCEDURE event_trigger_report_dropped();
+CREATE SCHEMA evttrig
+	CREATE TABLE one (col_a SERIAL PRIMARY KEY, col_b text DEFAULT 'forty two')
+	CREATE INDEX one_idx ON one (col_b)
+	CREATE TABLE two (col_c INTEGER CHECK (col_c > 0) REFERENCES one DEFAULT 42);
+
+ALTER TABLE evttrig.two DROP COLUMN col_c;
+ALTER TABLE evttrig.one ALTER COLUMN col_b DROP DEFAULT;
+ALTER TABLE evttrig.one DROP CONSTRAINT one_pkey;
+DROP INDEX evttrig.one_idx;
+DROP SCHEMA evttrig CASCADE;
+
+DROP EVENT TRIGGER regress_event_trigger_report_dropped;
+
 -- only allowed from within an event trigger function, should fail
 select pg_event_trigger_table_rewrite_oid();