= IMPORTANT WARNING =
This can be a VERY EXPENSIVE MIGRATION which may take hours or
days to run depending on the size of the courseware_studentmodule
table on your site. Depending on your database, it may also lock
this table, causing courseware to be non-functional during that
time.
If you want to run this migration manually in a more controlled
way (separate from your release pipeline), the SQL needed is:
CREATE INDEX `courseware_stats` ON `courseware_studentmodule`
(`module_id`, `grade`, `student_id`);
You can then fake the migration:
https://docs.djangoproject.com/en/2.2/ref/django-admin/#cmdoption-migrate-fake
= Motivation and Background =
TLDR: This adds an index that will speed up reports like the
Problem Grade Report. This fixes a performance regression that
was unintentionally introduced in 25da206c.
I'm capturing the entire saga below, in case Open edX operators
need to dig into it.
The tale begins in November of 2012 (yes, seriously). We had an
inline analytics feature that would display a histogram to course
staff by each problem in the LMS, detailing how students did on
that problem (e.g. 80% got 2 points, 10% got 1 point, 10% got 0
points). The courseware_studentmodule table already had an index
on the module_id (a.k.a. module_state_key), but because there
were 100K+ students that had student state for some problems,
the generation of those histograms was still extremely expensive.
During U.S. Thanksgiving weekend in late November of 2012, that
load started causing operational failures on edx.org.
As an emergency measure, I manually added a composite index for
(module_id, grade, student_id) on courseware_studentmodule in
order to stabilize the courseware on edx.org. I did _not_ follow
up properly and add it in a migration file. Later on, the inline
analytics feature was removed entirely, so the index was considered
redundant (but again, it was not properly cleaned up).
Various reports were created over the years, some of which
relied on having an index for module_id. These ran fine because
there had long been an index for that field specifically.
In 2018, the courseware_studentmodule table for edx.org ran into
the 2 TB size limit that our old RDS instance had. We had a fair
amount of monitoring for various limits that we thought we might
run into, but the per-table limit took us by surprise. The Devops/
SRE person fielding that issue needed to free up space in a hurry
in order to make the courseware functional again. Examining the
database itself, he noticed that we had a module_id index that was
technically redundant because the composite index of (module_id,
grade, student_id) would cover queries that would otherwise use it.
Again, as an emergency measure, he dropped the index on module_id
in order to free up a little space and buy enough time to do a
proper move of the database to Aurora.
Devops-of-2018 being more disciplined than me-of-2012, the index
on module_id was removed in 25da206c. The intention was to make it
so that the state of the code would match what was live on edx.org.
But because the composite index was added in an ad hoc way, what
that really meant was that now queries involving module_id were
_only_ indexed by the (module_id, grade, student_id) composite
index that existed only on edx.org and no other Open edX instances.
We didn't realize this issue until months later. @blarghmatey
created an index to re-add the index for module_id:
https://github.com/edx/edx-platform/pull/20885
The reason why we didn't accept this immediately is because
migrations for this table are very operationally risky and take
days to run. Faking this migration would have put edx.org even
more out of sync with the Open edX repo. Complicating this
somewhat was the fact that some folks still seem to be running a
variant of the inline analytics on their fork.
So in the end, we're going forward with this migration that brings
the code fully into sync with indexes on edx.org and covers the
obscure inline analytics histogram use case, while still covering
the module_id index needed for the fast generation of certain
reports that focus on a single problem.
Sorry folks.
In commit 9b37e7d0, the logic of
`streak_celebration_is_active` was accidentally
changed such that it no longer checks the
Progress Milestones waffle flag.
This commit fixes that.
Note: This also adds in a transitive check to
`courseware_mfe_is_active`,
which makes sense for Streak Celebration
and should not have any functional impact.
* Adds the backfill_course_outlines management command to contentstore
* Adds a read-only Django admin interface to learning_sequences for the
support team and debugging.
* Adds two new functions to the learning_sequences public API:
key_supports_outlines and get_course_keys_with_outlines
The learning_sequences app isn't supposed to know about contentstore or
modulestore, as it's intended to be extracted out of edx-platform in the
long term. Therefore, the backfill_course_outlines command is in
contentstore, and not learning_sequences.
This work was tracked in TNL-7983, but it also fixes a bug where we were
trying to generate course outlines for libraries (TNL-7981).
All Open edX instances upgrading to Lilac should run the
backfill_course_outlines command as part of their upgrade process.
Centralize the logic for choosing between
MFE and Legacy-frontend courseware within
three new functions:
* courseware_mfe_is_active
* courseware_mfe_is_visible
* courseware_legacy_is_visible
This allows us to create another new function:
* get_courseware_url
which can be called anywhere in LMS/Studio
to get the canonical URL to courseware
content (whether it be MFE or Legacy).
In future commits we we begin using
get_courseware_url throughout the platform.
TNL-7796
The docs configuration files previously had to account
for the fact that lms/djangoapps, cms/djangoapps, and
common/djangoapps were hacked into sys.path. As of ~Lilac,
this is no longer the case.
Unrelated cleanup: devstack_docker and devstack
are now aliases, so we can simplify a conditional import
in docs_settings.py
The timeline of the import_shims removal has evolved
over time; notably, we are keeping the import_shims
in Lilac in order to make any lingering old-style
import paths obvious to operators.
Update the ADR to reflect this. Also, add a table
mapping old import paths to new ones.
Previously, deprecated [lms|cms|common]/djangoapps
import paths would only raise errors if the
ERROR_ON_DEPRECATED_EDX_PLATFORM_IMPORTS
flag, which defaulted to False (but is overriden
to True for Devstack and *.edx.org), was enabled.
This change removes that setting and always raises
on use those deprecated import paths.
When we tried upgrading Jenkins workers from Ubuntu 16.04 to 20.04, `diff-cover` started silently failing with a return code of `1`. We suspect this is due to https://github.com/Bachmann1234/diff_cover/issues/153 , so we're adding the workaround described in that ticket.
S3 URLs served by Blockstore have a max TTL of
1hr, since the temporary credentials the Blockstore
uses to sign the URLs themselves have a TTL of
1hr. Thus, we must cache Blockstore bundles for
less than 1hr.
TNL-7771
