diff -r cb27485ef5ae -r 4cc020ee70e2 server/sources/rql2sql.py
--- a/server/sources/rql2sql.py	Wed Mar 24 17:58:05 2010 +0100
+++ b/server/sources/rql2sql.py	Wed Mar 24 18:04:59 2010 +0100
@@ -73,7 +73,7 @@
     modified = False
     for varname in tuple(unstable):
         var = select.defined_vars[varname]
-        if not var.stinfo['optrelations']:
+        if not var.stinfo.get('optrelations'):
             continue
         modified = True
         unstable.remove(varname)
@@ -100,13 +100,13 @@
             var.stinfo['relations'].remove(rel)
             newvar.stinfo['relations'].add(newrel)
             if rel.optional in ('left', 'both'):
-                newvar.stinfo['optrelations'].add(newrel)
+                newvar.add_optional_relation(newrel)
             for vref in newrel.children[1].iget_nodes(VariableRef):
                 var = vref.variable
                 var.stinfo['relations'].add(newrel)
                 var.stinfo['rhsrelations'].add(newrel)
                 if rel.optional in ('right', 'both'):
-                    var.stinfo['optrelations'].add(newrel)
+                    var.add_optional_relation(newrel)
         # extract subquery solutions
         mysolutions = [sol.copy() for sol in solutions]
         cleanup_solutions(newselect, mysolutions)
@@ -816,7 +816,7 @@
                         condition = '%s=%s' % (lhssql, rhsconst.accept(self))
                         if relation.r_type != 'identity':
                             condition = '(%s OR %s IS NULL)' % (condition, lhssql)
-                        if not lhsvar.stinfo['optrelations']:
+                        if not lhsvar.stinfo.get('optrelations'):
                             return condition
                         self.add_outer_join_condition(lhsvar, t1, condition)
                     return
@@ -909,7 +909,7 @@
                 sql = '%s%s' % (lhssql, rhssql)
         except AttributeError:
             sql = '%s%s' % (lhssql, rhssql)
-        if lhs.variable.stinfo['optrelations']:
+        if lhs.variable.stinfo.get('optrelations'):
             self.add_outer_join_condition(lhs.variable, table, sql)
         else:
             return sql
@@ -924,7 +924,7 @@
         lhsvar = lhs.variable
         me_is_principal = lhsvar.stinfo.get('principal') is rel
         if me_is_principal:
-            if not lhsvar.stinfo['typerels']:
+            if lhsvar.stinfo['typerel'] is None:
                 # the variable is using the fti table, no join needed
                 jointo = None
             elif not lhsvar.name in self._varmap:
@@ -1053,7 +1053,7 @@
                 vtablename = '_' + variable.name
                 self.add_table('entities AS %s' % vtablename, vtablename)
                 sql = '%s.eid' % vtablename
-                if variable.stinfo['typerels']:
+                if variable.stinfo['typerel'] is not None:
                     # add additional restriction on entities.type column
                     pts = variable.stinfo['possibletypes']
                     if len(pts) == 1:
@@ -1207,7 +1207,7 @@
             tablealias = self._state.outer_tables[table]
             actualtables = self._state.actual_tables[-1]
         except KeyError:
-            for rel in var.stinfo['optrelations']:
+            for rel in var.stinfo.get('optrelations'):
                 self.visit_relation(rel)
             assert self._state.outer_tables
             self.add_outer_join_condition(var, table, condition)