Description
This is a follow up to #29058 and #29413. This is the next step in moving part of the modulestore data (the course indexes / "active versions" table) from MongoDB to MySQL.
There are four steps planned in moving course index data to MySQL:
Step 1: create the tables in MySQL, start writing to MySQL + MongoDB ✅ done
Step 2: migrate all remaining courses to MySQL ✅ done
Step 3: switch reads from MongoDB to MySQL (this PR)
Step 4 (much later, once we know this is working well): stop writing to MongoDB altogether.
Supporting information
OpenCraft Jira ticket: MNG-2557
Status
✅ Tested with a large Open edX instance is in progress.
Testing instructions
Try making changes in Studio and verify that they work fine.
Deadline
None
Split modulestore persists data in three MongoDB "collections": course_index (list of courses and the current version of each), structure (outline of the courses, and some XBlock fields), and definition (other XBlock fields). While "structure" and "definition" data can get very large, which is one of the reasons MongoDB was chosen for modulestore, the course index data is very small.
This commit starts writing course indexes (active_versions) to both MySQL and Mongo, but continues to read from MongoDB only.
By moving course index data to MySQL / a django model, we get these advantages:
* Full history of changes to the course index data is now preserved
* Includes a django admin view to inspect the list of courses and libraries
* It's much easier to "reset" a corrupted course to a known working state, by using the simple-history revert tools from the django admin.
* The remaining MongoDB collections (structure and definition) are essentially just used as key-value stores of large JSON data structures. This paves the way for future changes that allow migrating courses one at a time from MongoDB to S3, and thus eliminating any use of MongoDB by split modulestore, simplifying the stack.
Split modulestore persists data in three MongoDB "collections": course_index (list of courses and the current version of each), structure (outline of the courses, and some XBlock fields), and definition (other XBlock fields). While "structure" and "definition" data can get very large, which is one of the reasons MongoDB was chosen for modulestore, the course index data is very small.
By moving course index data to MySQL / a django model, we get these advantages:
* Full history of changes to the course index data is now preserved
* Includes a django admin view to inspect the list of courses and libraries
* It's much easier to "reset" a corrupted course to a known working state, by using the simple-history revert tools from the django admin.
* The remaining MongoDB collections (structure and definition) are essentially just used as key-value stores of large JSON data structures. This paves the way for future changes that allow migrating courses one at a time from MongoDB to S3, and thus eliminating any use of MongoDB by split modulestore, simplifying the stack.
* Generate common/djangoapps import shims for LMS
* Generate common/djangoapps import shims for Studio
* Stop appending project root to sys.path
* Stop appending common/djangoapps to sys.path
* Import from common.djangoapps.course_action_state instead of course_action_state
* Import from common.djangoapps.course_modes instead of course_modes
* Import from common.djangoapps.database_fixups instead of database_fixups
* Import from common.djangoapps.edxmako instead of edxmako
* Import from common.djangoapps.entitlements instead of entitlements
* Import from common.djangoapps.pipline_mako instead of pipeline_mako
* Import from common.djangoapps.static_replace instead of static_replace
* Import from common.djangoapps.student instead of student
* Import from common.djangoapps.terrain instead of terrain
* Import from common.djangoapps.third_party_auth instead of third_party_auth
* Import from common.djangoapps.track instead of track
* Import from common.djangoapps.util instead of util
* Import from common.djangoapps.xblock_django instead of xblock_django
* Add empty common/djangoapps/__init__.py to fix pytest collection
* Fix pylint formatting violations
* Exclude import_shims/ directory tree from linting
Some tests were still relying on deprecated
WaffleSwitchNamespace.override method, which was working before because
we were importing WaffleSwitchNamespace from waffle_utils.__init__. This
no longer works after we import WaffleSwitchNamespace from edx-toggles.
