#16708: Session backend cached_db's exists() does not check cache before
database
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Reporter: jpvale@… | Owner: nobody
Type: | Status: new
Cleanup/optimization | Component: contrib.sessions
Milestone: | Severity: Normal
Version: SVN | Keywords: session cache
Resolution: | cached_db
Triage Stage: Design | Has patch: 1
decision needed | Needs tests: 1
Needs documentation: 0 | Easy pickings: 0
Patch needs improvement: 0 |
UI/UX: 0 |
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Changes (by aaugustin):
* needs_better_patch: => 0
* stage: Unreviewed => Design decision needed
* needs_tests: => 1
* needs_docs: => 0
Comment:
This file was never modified since it was checked in at r9727.
The current behavior may be an omission that went through the reviews
unnoticed, or an implementation choice: it avoids loading the contents of
the session just to check if it exists. The comments on #6791 don't
mention it.
Since Django's cache API doesn't provide `cache.exists(key)`, there's no
way to check if a session exists in the cache without getting the contents
of the session. It's impossible to optimize this for the general case,
because it depends on the speed/scalability of the database, the
speed/scalability of the cache, and the size of the session.
Since sessions tend to be small, I'm +0 on this change.
If it's accepted, the patch would need tests.
--
Ticket URL: <https://code.djangoproject.com/ticket/16708#comment:1>
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