Function DropObjectById

src/backend/catalog/dependency.c:1297–1354

* Drop an object by OID. Works for most catalogs, if no special processing * is needed. */

 * is needed.
 */
static void
DropObjectById(const ObjectAddress *object)
{
	int			cacheId;
	Relation	rel;
	HeapTuple	tup;

	/*
	* GPDB_14_MERGE_FIXME: specific for GPDB's pg_stat_last_* tables.
	* TODO: check more objects as api changed.
	*/
	if ((Gp_role == GP_ROLE_DISPATCH) && (OCLASS_TRANSFORM == getObjectClass(object)))
		MetaTrackDropObject(TransformRelationId, object->objectId);

	cacheId = get_object_catcache_oid(object->classId);

	rel = table_open(object->classId, RowExclusiveLock);

	/*
	 * Use the system cache for the oid column, if one exists.
	 */
	if (cacheId >= 0)
	{
		tup = SearchSysCache1(cacheId, ObjectIdGetDatum(object->objectId));
		if (!HeapTupleIsValid(tup))
			elog(ERROR, "cache lookup failed for %s %u",
				 get_object_class_descr(object->classId), object->objectId);

		CatalogTupleDelete(rel, &tup->t_self);

		ReleaseSysCache(tup);
	}
	else
	{
		ScanKeyData skey[1];
		SysScanDesc scan;

		ScanKeyInit(&skey[0],
					get_object_attnum_oid(object->classId),
					BTEqualStrategyNumber, F_OIDEQ,
					ObjectIdGetDatum(object->objectId));

		scan = systable_beginscan(rel, get_object_oid_index(object->classId), true,
								  NULL, 1, skey);

		/* we expect exactly one match */
		tup = systable_getnext(scan);
		if (!HeapTupleIsValid(tup))
			elog(ERROR, "could not find tuple for %s %u",
				 get_object_class_descr(object->classId), object->objectId);

		CatalogTupleDelete(rel, &tup->t_self);

		systable_endscan(scan);
	}

	table_close(rel, RowExclusiveLock);
}