Function getExtensionMembership

src/bin/pg_dump/pg_dump.c:20424–20492

* getExtensionMembership --- obtain extension membership data * * We need to identify objects that are extension members as soon as they're * loaded, so that we can correctly determine whether they need to be dumped. * Generally speaking, extension member objects will get marked as *not* to * be dumped, as they will be recreated by the single CREATE EXTENSION * command. However, in binary u

 * individually.
 */
void
getExtensionMembership(Archive *fout, ExtensionInfo extinfo[],
					   int numExtensions)
{
	PQExpBuffer query;
	PGresult   *res;
	int			ntups,
				i;
	int			i_classid,
				i_objid,
				i_refobjid;
	ExtensionInfo *ext;

	/* Nothing to do if no extensions */
	if (numExtensions == 0)
		return;

	query = createPQExpBuffer();

	/* refclassid constraint is redundant but may speed the search */
	appendPQExpBufferStr(query, "SELECT "
						 "classid, objid, refobjid "
						 "FROM pg_depend "
						 "WHERE refclassid = 'pg_extension'::regclass "
						 "AND deptype = 'e' "
						 "ORDER BY 3");

	res = ExecuteSqlQuery(fout, query->data, PGRES_TUPLES_OK);

	ntups = PQntuples(res);

	i_classid = PQfnumber(res, "classid");
	i_objid = PQfnumber(res, "objid");
	i_refobjid = PQfnumber(res, "refobjid");

	/*
	 * Since we ordered the SELECT by referenced ID, we can expect that
	 * multiple entries for the same extension will appear together; this
	 * saves on searches.
	 */
	ext = NULL;

	for (i = 0; i < ntups; i++)
	{
		CatalogId	objId;
		Oid			extId;

		objId.tableoid = atooid(PQgetvalue(res, i, i_classid));
		objId.oid = atooid(PQgetvalue(res, i, i_objid));
		extId = atooid(PQgetvalue(res, i, i_refobjid));

		if (ext == NULL ||
			ext->dobj.catId.oid != extId)
			ext = findExtensionByOid(extId);

		if (ext == NULL)
		{
			/* shouldn't happen */