Comment supportpr_github_284

Implementation of [#1546 (BitBucket)](https://bitbucket.org/zzzeek/sqlalchemy/issues/1546).

Very unfinished but I have reflection and setting after table creation working for PostgreSQL.

If you're not opposed, perhaps best to continue discussion on Gerrit?

Change-Id: Ib90683850805a2b4ee198e420dc294f32f15d35d
Pull-request: https://github.com/zzzeek/sqlalchemy/pull/284

1 files changed, 22 insertions, 0 deletions

diff --git a/lib/sqlalchemy/sql/compiler.py b/lib/sqlalchemy/sql/compiler.py
index 6d9ab9039..b26b0d1a7 100644
--- a/lib/sqlalchemy/sql/compiler.py
+++ b/lib/sqlalchemy/sql/compiler.py
@@ -2396,6 +2396,28 @@ class DDLCompiler(Compiled):
             self.process(create.element)
         )
 
+    def visit_set_table_comment(self, create):
+        return "COMMENT ON TABLE %s IS %s" % (
+            self.preparer.format_table(create.element),
+            self.sql_compiler.render_literal_bindparam(
+                elements.BindParameter('comment', value=create.comment))
+        )
+
+    def visit_drop_table_comment(self, drop):
+        return "COMMENT ON TABLE %s IS NULL" % \
+            self.preparer.format_table(drop.element)
+
+    def visit_set_column_comment(self, create):
+        return "COMMENT ON COLUMN %s IS %s" % (
+            self.preparer.format_column(create.element, use_table=True),
+            self.sql_compiler.render_literal_bindparam(
+                elements.BindParameter('comment', value=create.comment))
+        )
+
+    def visit_drop_column_comment(self, drop):
+        return "COMMENT ON COLUMN %s IS NULL" % \
+            self.preparer.format_column(drop.element, use_table=True)
+
     def visit_create_sequence(self, create):
         text = "CREATE SEQUENCE %s" % \
             self.preparer.format_sequence(create.element)