Add an index to compute_node_stats

This will improve the performance of scheduler lookups of compute nodes
and their associated stats.

bug 1177487

Change-Id: I0e04849543916e874ea0ddfc76c3d70ff71c09d0

1 files changed, 37 insertions, 0 deletions

diff --git a/nova/db/sqlalchemy/migrate_repo/versions/178_add_index_to_compute_node_stats.py b/nova/db/sqlalchemy/migrate_repo/versions/178_add_index_to_compute_node_stats.py
new file mode 100644
index 000000000..c6a4d1527
--- /dev/null
+++ b/nova/db/sqlalchemy/migrate_repo/versions/178_add_index_to_compute_node_stats.py
@@ -0,0 +1,37 @@
+# Copyright 2013 Rackspace Hosting
+# All Rights Reserved.
+#
+#    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.
+
+from sqlalchemy import Index, MetaData, Table
+
+
+TABLE_NAME = 'compute_node_stats'
+IDX_NAME = 'compute_node_stats_node_id_and_deleted_idx'
+
+
+def upgrade(migrate_engine):
+    """Add an index to make the scheduler lookups of compute_nodes and joined
+    compute_node_stats more efficient.
+    """
+    meta = MetaData(bind=migrate_engine)
+    cn_stats = Table(TABLE_NAME, meta, autoload=True)
+    idx = Index(IDX_NAME, cn_stats.c.compute_node_id, cn_stats.c.deleted)
+    idx.create(migrate_engine)
+
+
+def downgrade(migrate_engine):
+    meta = MetaData(bind=migrate_engine)
+    cn_stats = Table(TABLE_NAME, meta, autoload=True)
+    idx = Index(IDX_NAME, cn_stats.c.compute_node_id, cn_stats.c.deleted)
+    idx.drop(migrate_engine)