From e52106e91c6fbf0c5f12c5c81d9df62f517034a1 Mon Sep 17 00:00:00 2001
From: Mike Bayer <mike_mp@zzzcomputing.com>
Date: Wed, 25 Jan 2017 09:34:41 -0500
Subject: [PATCH] - add a note that alter_column->postgresql_using is raw SQL,
 fixes #408

Change-Id: Ia569191d43d49178f78a7bcef458b671f750583e
---
 alembic/operations/ops.py | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/alembic/operations/ops.py b/alembic/operations/ops.py
index f892227c..8957982c 100644
--- a/alembic/operations/ops.py
+++ b/alembic/operations/ops.py
@@ -1399,7 +1399,9 @@ class AlterColumnOp(AlterTableOp):
 
         :param postgresql_using: String argument which will indicate a
          SQL expression to render within the Postgresql-specific USING clause
-         within ALTER COLUMN.
+         within ALTER COLUMN.    This string is taken directly as raw SQL which
+         must explicitly include any necessary quoting or escaping of tokens
+         within the expression.
 
          .. versionadded:: 0.8.8
 
-- 
2.47.2