- [feature] Added "MATCH" clause to ForeignKey,

ForeignKeyConstraint, courtesy Ryan Kelly.
[ticket:2502]
- [feature] Added support for DELETE and UPDATE from
an alias of a table, which would assumedly
be related to itself elsewhere in the query,
courtesy Ryan Kelly.  [ticket:2507]
- [feature] Added support for the Postgresql ONLY
keyword, which can appear corresponding to a
table in a SELECT, UPDATE, or DELETE statement.
The phrase is established using with_hint().
Courtesy Ryan Kelly [ticket:2506]

1 files changed, 23 insertions, 0 deletions

diff --git a/lib/sqlalchemy/dialects/postgresql/base.py b/lib/sqlalchemy/dialects/postgresql/base.py
index 7363b2334..248d39ed6 100644
--- a/lib/sqlalchemy/dialects/postgresql/base.py
+++ b/lib/sqlalchemy/dialects/postgresql/base.py
@@ -114,6 +114,24 @@ use the :meth:`._UpdateBase.returning` method on a per-statement basis::
         where(table.c.name=='foo')
     print result.fetchall()
 
+FROM ONLY ...
+------------------------
+
+The dialect supports PostgreSQL's ONLY keyword for targeting only a particular
+table in an inheritance hierarchy. This can be used to produce the
+``SELECT ... FROM ONLY``, ``UPDATE ONLY ...``, and ``DELETE FROM ONLY ...``
+syntaxes. It uses SQLAlchemy's hints mechanism:
+
+    # SELECT ... FROM ONLY ...
+    result = table.select().with_hint(table, 'ONLY', 'postgresql')
+    print result.fetchall()
+
+    # UPDATE ONLY ...
+    table.update(values=dict(foo='bar')).with_hint('ONLY',
+                                                   dialect_name='postgresql')
+
+    # DELETE FROM ONLY ...
+    table.delete().with_hint('ONLY', dialect_name='postgresql')
 
 .. _postgresql_indexes:
 
@@ -642,6 +660,11 @@ class PGCompiler(compiler.SQLCompiler):
             text += " OFFSET " + self.process(sql.literal(select._offset))
         return text
 
+    def format_from_hint_text(self, sqltext, table, hint, iscrud):
+        if hint.upper() != 'ONLY':
+            raise exc.CompileError("Unrecognized hint: %r" % hint)
+        return "ONLY " + sqltext
+
     def get_select_precolumns(self, select):
         if select._distinct is not False:
             if select._distinct is True: