Add index for actor_id in assignments table.

Searching the assignments table by actor_id is a common occurance
and in a large OpenStack installation, this can be a significant
performance degradation.  This table is read much more often than
it is written, so this should be a good trade off.

Change-Id: Ia1a4392ca2118690a10130b10b2f69cd05672a12
Closes-bug: 1362557

keystone/assignment/backends/sql.py

@@ -638,7 +638,7 @@ class RoleAssignment(sql.ModelBase, sql.DictBase):
                  AssignmentType.USER_DOMAIN, AssignmentType.GROUP_DOMAIN,
                  name='type'),
         nullable=False)
-    actor_id = sql.Column(sql.String(64), nullable=False)
+    actor_id = sql.Column(sql.String(64), nullable=False, index=True)
     target_id = sql.Column(sql.String(64), nullable=False)
     role_id = sql.Column(sql.String(64), sql.ForeignKey('role.id'),
                          nullable=False)

keystone/common/sql/migrate_repo/versions/054_add_actor_id_index.py

@@ -0,0 +1,35 @@
+# Copyright 2014 IBM Corp.
+#
+# Licensed under the Apache License, Version 2.0 (the "License"); you may
+# not use this file except in compliance with the License. You may obtain
+# a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+# License for the specific language governing permissions and limitations
+# under the License.
+
+import sqlalchemy as sql
+
+ASSIGNMENT_TABLE = 'assignment'
+
+
+def upgrade(migrate_engine):
+    meta = sql.MetaData()
+    meta.bind = migrate_engine
+
+    assignment = sql.Table(ASSIGNMENT_TABLE, meta, autoload=True)
+    idx = sql.Index('ix_actor_id', assignment.c.actor_id)
+    idx.create(migrate_engine)
+
+
+def downgrade(migrate_engine):
+    meta = sql.MetaData()
+    meta.bind = migrate_engine
+
+    assignment = sql.Table(ASSIGNMENT_TABLE, meta, autoload=True)
+    idx = sql.Index('ix_actor_id', assignment.c.actor_id)
+    idx.drop(migrate_engine)

keystone/tests/test_sql_upgrade.py

@@ -1386,6 +1386,20 @@ class SqlUpgradeTests(SqlMigrateBase):
         self.assertEqual(1, session.query(endpoint_table).
                          filter_by(region=_small_region_name).count())
 
+    def test_add_actor_id_index(self):
+        self.upgrade(53)
+        self.upgrade(54)
+        table = sqlalchemy.Table('assignment', self.metadata, autoload=True)
+        index_data = [(idx.name, idx.columns.keys()) for idx in table.indexes]
+        self.assertIn(('ix_actor_id', ['actor_id']), index_data)
+
+    def test_remove_actor_id_index(self):
+        self.upgrade(54)
+        self.downgrade(53)
+        table = sqlalchemy.Table('assignment', self.metadata, autoload=True)
+        index_data = [(idx.name, idx.columns.keys()) for idx in table.indexes]
+        self.assertNotIn(('ix_actor_id', ['actor_id']), index_data)
+
     def populate_user_table(self, with_pass_enab=False,
                             with_pass_enab_domain=False):
         # Populate the appropriate fields in the user