The documentation for the Django database backend says:
Unlike other cache backends, the database cache does not support
automatic culling of expired entries at the database level.
Instead, expired cache entries are culled each time
add(), set(), or touch() is called.
But this doesn’t seem to be what is happening:
In fact, expired entries are only deleted if MAX_ENTRIES is reached: https://github.com/django/django/blob/main/django/core/cache/backends/db.py#L130
But this then also triggers culling of non-expired entries if their number exceeds MAX_ENTRIES.
This is a problem if I want to drive a strategy where I only expire entries by time and never randomly cull them. In order to prevent random culling, I need to set MAX_ENTRIES to a very high unreachable number. But then, expired entries will never be deleted!
Am I maybe missing something? Or is the documentation incomplete here?
Is it a possible consideration to update the database caching backend to cull expired entries also when MAX_ENTRIES isn’t reached yet?
PS: The documentation also doesn’t mention that expired entries are removed if you try to get them: https://github.com/django/django/blob/main/django/core/cache/backends/db.py#L97