Don't reorder PrimaryKeyConstraint columns if explicit

Dialed back the "order the primary key columns per auto-increment"
described in :ref:`change_mysql_3216` a bit, so that if the
:class:`.PrimaryKeyConstraint` is explicitly defined, the order
of columns is maintained exactly, allowing control of this behavior
when necessary.

Change-Id: I9e7902c57a96c15968a6abf53e319acf15680da0
Fixes: #3726

1 files changed, 17 insertions, 1 deletions

diff --git a/test/sql/test_compiler.py b/test/sql/test_compiler.py
index 8b4e5053b..27cab65ac 100644
--- a/test/sql/test_compiler.py
+++ b/test/sql/test_compiler.py
@@ -3066,7 +3066,7 @@ class DDLTest(fixtures.TestBase, AssertsCompiledSQL):
             "CREATE TABLE t (x INTEGER, z INTEGER)"
         )
 
-    def test_composite_pk_constraint_autoinc_first(self):
+    def test_composite_pk_constraint_autoinc_first_implicit(self):
         m = MetaData()
         t = Table(
             't', m,
@@ -3081,6 +3081,22 @@ class DDLTest(fixtures.TestBase, AssertsCompiledSQL):
             "PRIMARY KEY (b, a))"
         )
 
+    def test_composite_pk_constraint_maintains_order_explicit(self):
+        m = MetaData()
+        t = Table(
+            't', m,
+            Column('a', Integer),
+            Column('b', Integer, autoincrement=True),
+            schema.PrimaryKeyConstraint('a', 'b')
+        )
+        self.assert_compile(
+            schema.CreateTable(t),
+            "CREATE TABLE t ("
+            "a INTEGER NOT NULL, "
+            "b INTEGER NOT NULL, "
+            "PRIMARY KEY (a, b))"
+        )
+
     def test_create_table_suffix(self):
         class MyDialect(default.DefaultDialect):
             class MyCompiler(compiler.DDLCompiler):