Function getExtensionOfObject

src/backend/catalog/pg_depend.c:764–804

* Find the extension containing the specified object, if any * * Returns the OID of the extension, or InvalidOid if the object does not * belong to any extension. * * Extension membership is marked by an EXTENSION dependency from the object * to the extension. Note that the result will be indeterminate if pg_depend * contains links from this object to more than one extension ... but that

 * should never happen.
 */
Oid
getExtensionOfObject(Oid classId, Oid objectId)
{
	Oid			result = InvalidOid;
	Relation	depRel;
	ScanKeyData key[2];
	SysScanDesc scan;
	HeapTuple	tup;

	depRel = table_open(DependRelationId, AccessShareLock);

	ScanKeyInit(&key[0],
				Anum_pg_depend_classid,
				BTEqualStrategyNumber, F_OIDEQ,
				ObjectIdGetDatum(classId));
	ScanKeyInit(&key[1],
				Anum_pg_depend_objid,
				BTEqualStrategyNumber, F_OIDEQ,
				ObjectIdGetDatum(objectId));

	scan = systable_beginscan(depRel, DependDependerIndexId, true,
							  NULL, 2, key);

	while (HeapTupleIsValid((tup = systable_getnext(scan))))
	{
		Form_pg_depend depform = (Form_pg_depend) GETSTRUCT(tup);

		if (depform->refclassid == ExtensionRelationId &&
			depform->deptype == DEPENDENCY_EXTENSION)
		{
			result = depform->refobjid;
			break;				/* no need to keep scanning */
		}
	}

	systable_endscan(scan);

	table_close(depRel, AccessShareLock);

	return result;
}

/*
 * Return (possibly NIL) list of extensions that the given object depends on