- Query.distinct() now accepts column expressions

  as *args, interpreted by the Postgresql dialect
  as DISTINCT ON (<expr>). [ticket:1069]
- select.distinct() now accepts column expressions
  as *args, interpreted by the Postgresql dialect
  as DISTINCT ON (<expr>).  Note this was already
  available via passing a list to the `distinct`
  keyword argument to select(). [ticket:1069]
- select.prefix_with() accepts multiple expressions
  (i.e. *expr), 'prefix' keyword argument to select()
  accepts a list or tuple.
- Passing a string to the `distinct` keyword argument
  of `select()` for the purpose of emitting special
  MySQL keywords (DISTINCTROW etc.) is deprecated -
  use `prefix_with()` for this.
- put kw arguments to select() in order
- restore docs for _SelectBase, renamed from _SelectBaseMixin

2 files changed, 9 insertions, 3 deletions

diff --git a/lib/sqlalchemy/dialects/mysql/base.py b/lib/sqlalchemy/dialects/mysql/base.py
index 271218dba..21e0312f5 100644
--- a/lib/sqlalchemy/dialects/mysql/base.py
+++ b/lib/sqlalchemy/dialects/mysql/base.py
@@ -1176,6 +1176,13 @@ class MySQLCompiler(compiler.SQLCompiler):
         return value
 
     def get_select_precolumns(self, select):
+        """Add special MySQL keywords in place of DISTINCT.
+        
+        .. note:: this usage is deprecated.  :meth:`.Select.prefix_with`
+          should be used for special keywords at the start
+          of a SELECT.
+          
+        """
         if isinstance(select._distinct, basestring):
             return select._distinct.upper() + " "
         elif select._distinct:
diff --git a/lib/sqlalchemy/dialects/postgresql/base.py b/lib/sqlalchemy/dialects/postgresql/base.py
index 22d269cdf..8bc95ef48 100644
--- a/lib/sqlalchemy/dialects/postgresql/base.py
+++ b/lib/sqlalchemy/dialects/postgresql/base.py
@@ -457,11 +457,10 @@ class PGCompiler(compiler.SQLCompiler):
                 return "DISTINCT "
             elif isinstance(select._distinct, (list, tuple)):
                 return "DISTINCT ON (" + ', '.join(
-                    [(isinstance(col, basestring) and col 
-                        or self.process(col)) for col in select._distinct]
+                    [self.process(col) for col in select._distinct]
                 )+ ") "
             else:
-                return "DISTINCT ON (" + unicode(select._distinct) + ") "
+                return "DISTINCT ON (" + self.process(select._distinct) + ") "
         else:
             return ""