matomo-org/matomo

Redis cache: Prepend Matomo version number to cache key, and enforce a TTL

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#14,314 opened on Apr 4, 2019

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BugHelp wanted

Description

In https://matomo.org/faq/how-to/faq_20511/ we recommend to use the Redis cache when using multiple servers to run Matomo. This can result in many issues though eg when each server has a different path to the Matomo directory.

Also when updating Matomo on the servers, in most cases some servers will run a new Matomo version while other servers will run an older version of Matomo. Yet they all access the same cache. This is problematic because caches aren't compatible between Matomo versions, and they have different files etc. Meaning while deploying code (in for us takes sometimes 30min+ to update all servers) Matomo can be broken if someone uses redis cache. To workaround this issue we could prepend the Matomo version number to all cache IDs. To still invalidate the cache entries of older Matomo versions, we need to make sure that when a cache is saved with no TTL, we need to set eg 86400 to free space after a while.

I will mention in the FAQ that redis cache can only be used if they all have the same path.

Contributor guide

Tech stack
phpredis
Domain
backendperformance
Issue type
feature
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-2 days
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
PHPRedisMatomo caching
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
55
Research direction
Investigate the existing cache implementation in Matomo, particularly the Redis cache adapter, to understand how cache keys are currently generated. Look for the relevant files in the plugins/Core or libs/ directory. Add logic to prepend the Matomo version number to all cache IDs and enforce a TTL of 86400 seconds for entries without an explicit TTL. Review the comments in the issue for any additional context on compatibility.
Redis cache: Prepend Matomo version number to cache key, and enforce a TTL · matomo-org/matomo#14314 | Good First Issue