melanie witt 68f80d2013 Use subqueryload() instead of joinedload() for (system_)metadata ... Currently, when we "get" a single instance from the database and we load metadata and system_metadata, we do so using a joinedload() which does JOINs with the respective tables. Because of the one-to-many relationship between an instance and (system_)metadata records, doing the database query this way can result in a large number of additional rows being returned unnecessarily and cause a large data transfer. This is similar to the problem addressed by change I0610fb16ccce2ee95c318589c8abcc30613a3fe9 which added separate queries for (system_)metadata when we "get" multiple instances. We don't, however, reuse the same code for this change because _instances_fill_metadata converts the instance database object to a dict, and some callers of _instance_get_by_uuid need to be able to access an instance database object attached to the session (example: instance_update_and_get_original). By using subqueryload() [1], we can perform the additional queries for (system_)metadata to solve the problem with a similar approach. Closes-Bug: #1799298 [1] https://docs.sqlalchemy.org/en/13/orm/loading_relationships.html#subquery-eager-loading Change-Id: I5c071f70f669966e9807b38e99077c1cae5b4606 (cherry picked from commit e728fe668a) (cherry picked from commit 63d2e62c3a) (cherry picked from commit e7a45e0335) (cherry picked from commit 4350074029) (cherry picked from commit ad7e4fb8f4)		2021-03-29 15:07:52 +00:00
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sqlalchemy	Use subqueryload() instead of joinedload() for (system_)metadata	2021-03-29 15:07:52 +00:00
__init__.py	Use nova.db.api directly	2018-07-10 14:56:27 +00:00
api.py	Remove remaining legacy DB API instance_group* methods	2018-06-27 13:24:42 -04:00
base.py	Use nova.db.api directly	2018-07-10 14:56:27 +00:00
constants.py	Move db MAX constants to own file	2018-03-01 11:09:29 +00:00
migration.py	Manage db sync command for cell0	2016-08-22 18:53:45 +03:00