Redis prefix causes ever-growing redis cache size
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- Dominant language
- PHP
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Description
Whenever Nextcloud or an app is updated the Memcache prefix is changing and old stored keys without an expiry would just stay around forever. Since the prefix is also hashed and not easily genera table due to the app version list in place there is also currently no good way to clean them up manually.
Maybe we could consider having a predictable global prefix, so we could also introduce a nightly job to delete outdated keys?
On the other hand deleting keys by prefix is a rather heavy operation as it requires a KEYS and then a DEL for each key on the Redis side, so maybe a default expiry of some weeks would also be something that we could consider.
cc @nextcloud/server-backend
Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
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Research direction
Start by reading lib/private/Server.php around lines 712-726 to understand how the Redis Memcache prefix is built. The issue needs a decision between predictable-prefix cleanup and default expiry behavior; it is done when one approach is specified, implemented, and its handling of old keys is verified.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- php, redis
- Domain
- backend, databases
- Issue type
- Bug
- Difficulty
- 5/5
- Estimated time
- Over a week
- Activity status
- Stale
- Clarity
- Needs clarification
- Newbie friendliness
- 25/100