diff -r 12d226a5bab9 -r 7c565548fb09 cubicweb/server/schema2sql.py
--- a/cubicweb/server/schema2sql.py	Fri Apr 15 10:20:34 2016 +0200
+++ b/cubicweb/server/schema2sql.py	Mon Jun 20 15:04:14 2016 +0200
@@ -1,4 +1,4 @@
-# copyright 2004-2015 LOGILAB S.A. (Paris, FRANCE), all rights reserved.
+# copyright 2004-2016 LOGILAB S.A. (Paris, FRANCE), all rights reserved.
 # contact http://www.logilab.fr/ -- mailto:contact@logilab.fr
 #
 # This file is part of cubicweb.
@@ -31,6 +31,7 @@
 # SET_DEFAULT to True
 SET_DEFAULT = False
 
+
 def rschema_has_table(rschema, skip_relations):
     """Return True if the given schema should have a table in the database"""
     return not (rschema.final or rschema.inlined or rschema.rule or rschema.type in skip_relations)
@@ -82,15 +83,18 @@
               if not rschema.final and rschema.inlined]
     return attrs
 
+
 def unique_index_name(eschema, columns):
     return u'unique_%s' % md5((eschema.type +
-                              ',' +
-                              ','.join(sorted(columns))).encode('ascii')).hexdigest()
+                               ',' +
+                               ','.join(sorted(columns))).encode('ascii')).hexdigest()
+
 
 def iter_unique_index_names(eschema):
     for columns in eschema._unique_together or ():
         yield columns, unique_index_name(eschema, columns)
 
+
 def dropeschema2sql(dbhelper, eschema, skip_relations=(), prefix=''):
     """return sql to drop an entity type's table"""
     # not necessary to drop indexes, that's implictly done when
@@ -100,7 +104,7 @@
     tablename = prefix + eschema.type
     if eschema._unique_together is not None:
         for columns, index_name in iter_unique_index_names(eschema):
-            cols  = ['%s%s' % (prefix, col) for col in columns]
+            cols = ['%s%s' % (prefix, col) for col in columns]
             sqls = dbhelper.sqls_drop_multicol_unique_index(tablename, cols, index_name)
             statements += sqls
     statements += ['DROP TABLE %s;' % (tablename)]
@@ -120,7 +124,7 @@
         if attrschema is not None:
             sqltype = aschema2sql(dbhelper, eschema, rschema, attrschema,
                                   indent=' ')
-        else: # inline relation
+        else:  # inline relation
             sqltype = 'integer REFERENCES entities (eid)'
         if i == len(attrs) - 1:
             w(' %s%s %s' % (prefix, rschema.type, sqltype))
@@ -132,7 +136,8 @@
         attr = rschema.type
         rdef = rschema.rdef(eschema.type, aschema.type)
         for constraint in rdef.constraints:
-            cstrname, check = check_constraint(eschema, aschema, attr, constraint, dbhelper, prefix=prefix)
+            cstrname, check = check_constraint(eschema, aschema, attr, constraint, dbhelper,
+                                               prefix=prefix)
             if cstrname is not None:
                 w(', CONSTRAINT %s CHECK(%s)' % (cstrname, check))
     w(');')
@@ -142,13 +147,14 @@
         if attrschema is None or eschema.rdef(rschema).indexed:
             w(dbhelper.sql_create_index(table, prefix + rschema.type))
     for columns, index_name in iter_unique_index_names(eschema):
-        cols  = ['%s%s' % (prefix, col) for col in columns]
+        cols = ['%s%s' % (prefix, col) for col in columns]
         sqls = dbhelper.sqls_create_multicol_unique_index(table, cols, index_name)
         for sql in sqls:
             w(sql)
     w('')
     return '\n'.join(output)
 
+
 def as_sql(value, dbhelper, prefix):
     if isinstance(value, Attribute):
         return prefix + value.attr
@@ -160,6 +166,7 @@
         # XXX more quoting for literals?
         return value
 
+
 def check_constraint(eschema, aschema, attr, constraint, dbhelper, prefix=''):
     # XXX should find a better name
     cstrname = 'cstr' + md5((eschema.type + attr + constraint.type() +
@@ -186,6 +193,7 @@
         return cstrname, '%s%s IN (%s)' % (prefix, attr, values)
     return None, None
 
+
 def aschema2sql(dbhelper, eschema, rschema, aschema, creating=True, indent=''):
     """write an attribute schema as SQL statements to stdout"""
     attr = rschema.type
@@ -218,15 +226,15 @@
     """return a sql type string corresponding to the relation definition"""
     constraints = list(rdef.constraints)
     unique, sqltype = False, None
-    if rdef.object.type == 'String':
-        for constraint in constraints:
-            if isinstance(constraint, SizeConstraint):
-                if constraint.max is not None:
-                    size_constrained_string = dbhelper.TYPE_MAPPING.get(
-                        'SizeConstrainedString', 'varchar(%s)')
-                    sqltype = size_constrained_string % constraint.max
-            elif isinstance(constraint, UniqueConstraint):
-                unique = True
+    for constraint in constraints:
+        if isinstance(constraint, UniqueConstraint):
+            unique = True
+        elif (isinstance(constraint, SizeConstraint)
+              and rdef.object.type == 'String'
+              and constraint.max is not None):
+            size_constrained_string = dbhelper.TYPE_MAPPING.get(
+                'SizeConstrainedString', 'varchar(%s)')
+            sqltype = size_constrained_string % constraint.max
     if sqltype is None:
         sqltype = sql_type(dbhelper, rdef)
     if creating and unique: