Add name and tenant indexes to stack table

This change adds indexes to the name and tenant columns of the stack
table, to improve query performance.

Change-Id: I0c675bda1b27814c4a7e9fce6c78af48266b5258
Closes-Bug: #1421885

heat/db/sqlalchemy/migrate_repo/versions/053_stack_name_tenant_indexes.py

@@ -0,0 +1,40 @@
+#
+#    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
+
+
+def upgrade(migrate_engine):
+    meta = sqlalchemy.MetaData(bind=migrate_engine)
+    stack = sqlalchemy.Table('stack', meta, autoload=True)
+
+    name_index = sqlalchemy.Index('ix_stack_name', stack.c.name,
+                                  mysql_length=255)
+    name_index.create(migrate_engine)
+
+    tenant_index = sqlalchemy.Index('ix_stack_tenant', stack.c.tenant,
+                                    mysql_length=255)
+    tenant_index.create(migrate_engine)
+
+
+def downgrade(migrate_engine):
+    meta = sqlalchemy.MetaData(bind=migrate_engine)
+    stack = sqlalchemy.Table('stack', meta, autoload=True)
+
+    name_index = sqlalchemy.Index('ix_stack_name', stack.c.name,
+                                  mysql_length=255)
+    name_index.drop(migrate_engine)
+
+    tenant_index = sqlalchemy.Index('ix_stack_tenant', stack.c.tenant,
+                                    mysql_length=255)
+    tenant_index.drop(migrate_engine)

heat/db/sqlalchemy/models.py

@@ -113,6 +113,10 @@ class Stack(BASE, HeatBase, SoftDelete, StateAware):
     """Represents a stack created by the heat engine."""
 
     __tablename__ = 'stack'
+    __table_args__ = (
+        sqlalchemy.Index('ix_stack_name', 'name', mysql_length=255),
+        sqlalchemy.Index('ix_stack_tenant', 'tenant', mysql_length=255),
+    )
 
     id = sqlalchemy.Column(sqlalchemy.String(36), primary_key=True,
                            default=lambda: str(uuid.uuid4()))