Merge "avoid unnecessary inner join in get_resources() for SQL backend" into stable/kilo

1 files changed, 10 insertions, 3 deletions

diff --git a/ceilometer/storage/impl_sqlalchemy.py b/ceilometer/storage/impl_sqlalchemy.py
index 9eea27e6..09f6cc67 100644
--- a/ceilometer/storage/impl_sqlalchemy.py
+++ b/ceilometer/storage/impl_sqlalchemy.py
@@ -432,9 +432,16 @@ class Connection(base.Connection):
 
         session = self._engine_facade.get_session()
         # get list of resource_ids
-        res_q = session.query(distinct(models.Resource.resource_id)).join(
-            models.Sample,
-            models.Sample.resource_id == models.Resource.internal_id)
+        has_timestamp = start_timestamp or end_timestamp
+        # NOTE: When sql_expire_samples_only is enabled, there will be some
+        #       resources without any sample, in such case we should use inner
+        #       join on sample table to avoid wrong result.
+        if cfg.CONF.sql_expire_samples_only or has_timestamp:
+            res_q = session.query(distinct(models.Resource.resource_id)).join(
+                models.Sample,
+                models.Sample.resource_id == models.Resource.internal_id)
+        else:
+            res_q = session.query(distinct(models.Resource.resource_id))
         res_q = make_query_from_filter(session, res_q, s_filter,
                                        require_meter=False)