Drop unused PostgreSQL sequences from Folsom.

In Folsom the snapshots and volumes tables were converted to use
UUID's. When we performed this conversion in Folsom a couple of
unused PostgreSQL sequences were left behind.

This migration removes the snapshots_id_seq and volumes_id_seq
if they exist in the schema when using PostgreSQL.

Fixes LP Bug #1080786.

Change-Id: I075e2afebcb5236f96ab5d6ab13e249d078da86b

1 files changed, 61 insertions, 0 deletions

diff --git a/nova/db/sqlalchemy/migrate_repo/versions/140_drop_unused_postgresql_volume_sequences.py b/nova/db/sqlalchemy/migrate_repo/versions/140_drop_unused_postgresql_volume_sequences.py
new file mode 100644
index 000000000..18aa206fe
--- /dev/null
+++ b/nova/db/sqlalchemy/migrate_repo/versions/140_drop_unused_postgresql_volume_sequences.py
@@ -0,0 +1,61 @@
+# vim: tabstop=4 shiftwidth=4 softtabstop=4
+
+# Copyright (c) 2012 Red Hat, Inc.
+# 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 MetaData
+
+
+def upgrade(migrate_engine):
+    meta = MetaData()
+    meta.bind = migrate_engine
+
+    # NOTE(dprince): Remove unused snapshots/volumes sequences.
+    # These are leftovers from the ID --> UUID conversion for these tables
+    # that occurred in Folsom.
+    if migrate_engine.name == "postgresql":
+        base_query = """SELECT COUNT(*) FROM pg_class c
+                     WHERE c.relkind = 'S'
+                     AND relname = '%s';"""
+        result = migrate_engine.execute(base_query % "snapshots_id_seq")
+        if result.scalar() > 0:
+            sql = "DROP SEQUENCE snapshots_id_seq CASCADE;"
+            migrate_engine.execute(sql)
+
+        result = migrate_engine.execute(base_query % "volumes_id_seq")
+        if result.scalar() > 0:
+            sql = "DROP SEQUENCE volumes_id_seq CASCADE;"
+            migrate_engine.execute(sql)
+
+
+def downgrade(migrate_engine):
+    meta = MetaData()
+    meta.bind = migrate_engine
+
+    if migrate_engine.name == "postgresql":
+        sql = """CREATE SEQUENCE snapshots_id_seq START WITH 1 INCREMENT BY 1
+              NO MINVALUE NO MAXVALUE CACHE 1;
+              ALTER SEQUENCE snapshots_id_seq OWNED BY snapshots.id;
+              SELECT pg_catalog.setval('snapshots_id_seq', 1, false);
+              ALTER TABLE ONLY snapshots ALTER COLUMN id SET DEFAULT
+              nextval('snapshots_id_seq'::regclass);"""
+
+        sql += """CREATE SEQUENCE volumes_id_seq START WITH 1 INCREMENT BY 1
+               NO MINVALUE NO MAXVALUE CACHE 1;
+               ALTER SEQUENCE volumes_id_seq OWNED BY volumes.id;
+               SELECT pg_catalog.setval('volumes_id_seq', 1, false);
+               ALTER TABLE ONLY volumes ALTER COLUMN id SET DEFAULT
+               nextval('volumes_id_seq'::regclass);"""
+        migrate_engine.execute(sql)