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author | Zuul <zuul@review.opendev.org> | 2021-05-29 02:46:23 +0000 |
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committer | Gerrit Code Review <review@openstack.org> | 2021-05-29 02:46:23 +0000 |
commit | 7b90bcd92a171bff3c9df2b5b5405a38e4495563 (patch) | |
tree | 4f6fc7fd440d90256cf999055388c8776fba0d10 | |
parent | 5aa7f3b4e6241e21c69dc103bb7be847b500429c (diff) | |
parent | c1de4fb13e4c7d220ff2e42f24f06b4bbe53521f (diff) | |
download | nova-7b90bcd92a171bff3c9df2b5b5405a38e4495563.tar.gz |
Merge "Use subqueryload() instead of joinedload() for (system_)metadata" into stable/queens
-rw-r--r-- | nova/db/sqlalchemy/api.py | 17 | ||||
-rw-r--r-- | nova/tests/unit/db/test_db_api.py | 8 |
2 files changed, 24 insertions, 1 deletions
diff --git a/nova/db/sqlalchemy/api.py b/nova/db/sqlalchemy/api.py index ac577b873e..c571128591 100644 --- a/nova/db/sqlalchemy/api.py +++ b/nova/db/sqlalchemy/api.py @@ -49,6 +49,7 @@ from sqlalchemy.orm import contains_eager from sqlalchemy.orm import joinedload from sqlalchemy.orm import joinedload_all from sqlalchemy.orm import noload +from sqlalchemy.orm import subqueryload from sqlalchemy.orm import undefer from sqlalchemy.schema import Table from sqlalchemy import sql @@ -1919,13 +1920,27 @@ def _build_instance_get(context, columns_to_join=None): continue if 'extra.' in column: query = query.options(undefer(column)) + elif column in ['metadata', 'system_metadata']: + # NOTE(melwitt): We use subqueryload() instead of joinedload() for + # metadata and system_metadata because of the one-to-many + # relationship of the data. Directly joining these columns can + # result in a large number of additional rows being queried if an + # instance has a large number of (system_)metadata items, resulting + # in a large data transfer. Instead, the subqueryload() will + # perform additional queries to obtain metadata and system_metadata + # for the instance. + query = query.options(subqueryload(column)) else: query = query.options(joinedload(column)) # NOTE(alaski) Stop lazy loading of columns not needed. for col in ['metadata', 'system_metadata']: if col not in columns_to_join: query = query.options(noload(col)) - return query + # NOTE(melwitt): We need to use order_by(<unique column>) so that the + # additional queries emitted by subqueryload() include the same ordering as + # used by the parent query. + # https://docs.sqlalchemy.org/en/13/orm/loading_relationships.html#the-importance-of-ordering + return query.order_by(models.Instance.id) def _instances_fill_metadata(context, instances, manual_joins=None): diff --git a/nova/tests/unit/db/test_db_api.py b/nova/tests/unit/db/test_db_api.py index 37d11880ac..fe4452f835 100644 --- a/nova/tests/unit/db/test_db_api.py +++ b/nova/tests/unit/db/test_db_api.py @@ -2372,6 +2372,14 @@ class InstanceTestCase(test.TestCase, ModelsObjectComparatorMixin): sys_meta = utils.metadata_to_dict(inst['system_metadata']) self.assertEqual(sys_meta, self.sample_data['system_metadata']) + def test_instance_get_with_meta(self): + inst_id = self.create_instance_with_args().id + inst = db.instance_get(self.ctxt, inst_id) + meta = utils.metadata_to_dict(inst['metadata']) + self.assertEqual(meta, self.sample_data['metadata']) + sys_meta = utils.metadata_to_dict(inst['system_metadata']) + self.assertEqual(sys_meta, self.sample_data['system_metadata']) + def test_instance_update(self): instance = self.create_instance_with_args() metadata = {'host': 'bar', 'key2': 'wuff'} |