From 34a3a11c96d450083e225745fe919c688f65bbec Mon Sep 17 00:00:00 2001
From: gord chung <gord@live.ca>
Date: Sat, 13 Jun 2015 01:20:12 -0400
Subject: [PATCH] use union all when building trait query

union all is more performant as it doesn't need to filter out
duplicates. we should not have duplicates as the primary key
conditions already ensure that.

Change-Id: Ic25f7086b33a98ca77a669732a65be5a95b7f0db
---
 ceilometer/event/storage/impl_sqlalchemy.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/ceilometer/event/storage/impl_sqlalchemy.py b/ceilometer/event/storage/impl_sqlalchemy.py
index d4eb6f13..28b40859 100644
--- a/ceilometer/event/storage/impl_sqlalchemy.py
+++ b/ceilometer/event/storage/impl_sqlalchemy.py
@@ -282,7 +282,7 @@ class Connection(base.Connection):
                     sa.cast(sa.null(), sa.String(255)))
                 .filter(sa.exists().where(
                     models.TraitDatetime.event_id == query.subquery().c.id))
-            ).union(
+            ).union_all(
                 session.query(
                     models.TraitInt.event_id,
                     models.TraitInt.key, sa.null(),