Fixed sort key to not sort by an un-indexed field by default

* Added indices on domain, record and recordset tables for created_at
* Removed redundent extra sort param in _find()

Partially-Fixes: #1413472

Change-Id: Ic6c4274b0ce3d6c14ce02666df945aec1f838cc7

designate/sqlalchemy/base.py

@@ -242,7 +242,7 @@ class SQLAlchemy(object):
             try:
                 query = utils.paginate_query(
                     query, table, limit,
-                    [sort_key, 'id', 'created_at'], marker=marker,
+                    [sort_key, 'id'], marker=marker,
                     sort_dir=sort_dir)
 
                 resultproxy = self.session.execute(query)

designate/storage/impl_sqlalchemy/migrate_repo/versions/055_add_created_indices.py

@@ -0,0 +1,48 @@
+# Copyright (c) 2014 Rackspace Inc.
+#
+# Author: Tim Simmons <tim.simmons@rackspace.com>
+#
+# 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
+
+meta = MetaData()
+
+
+def index_exists(index):
+    table = index[1]._get_table()
+    cols = sorted([str(x).split('.')[1] for x in index[1:]])
+
+    for idx in table.indexes:
+        if sorted(idx.columns.keys()) == cols:
+            return True
+    return False
+
+
+def upgrade(migrate_engine):
+
+    meta.bind = migrate_engine
+
+    zones_table = Table('domains', meta, autoload=True)
+    recordsets_table = Table('recordsets', meta, autoload=True)
+    records_table = Table('records', meta, autoload=True)
+
+    indices = [
+        ['zone_created_at', zones_table.c.created_at],
+        ['recordset_created_at', recordsets_table.c.created_at],
+        ['record_created_at', records_table.c.created_at]
+    ]
+
+    for ind in indices:
+        if not index_exists(ind):
+            index = Index(*ind)
+            index.create(migrate_engine)