rails/solid_cache

Solid Cache is a cache store for Ruby on Rails applications that stores cached data in a regular database table instead of in memory. Rails already ships with cache stores backed by Redis or Memcached, which keep everything in RAM. Solid Cache takes a different approach: modern solid state drives are fast enough that reading from disk barely costs anything compared to reading from memory, so you can afford to keep a much bigger cache than would ever fit in RAM. Starting with Rails 8, Solid Cache is configured automatically in new applications. For earlier Rails versions, adding it is a two step process: add the gem with bundle add, then run the install generator, which sets up the production cache store and creates the database migration files needed for a cache table. You point Solid Cache at a database using a config file, either config/cache.yml or config/solid_cache.yml, and you can use a dedicated cache database, split the cache across multiple database shards, or just reuse your existing primary database connection. The cache is configurable in the usual Rails cache way, with options like a maximum age for entries, a maximum entry count, and a maximum total size in bytes. To keep the cache from growing forever, Solid Cache tracks how many writes have happened and periodically runs a background cleanup task, either on a background thread or as a queued job, that deletes old entries once the cache passes its size or age limits. For larger applications, Solid Cache can shard the cache across several databases using a consistent hashing scheme so that entries are spread out evenly and shards can be added or removed without disrupting the whole cache. This project comes from the official Rails organization and is meant as a drop in replacement wherever a traditional Rails cache store would normally be used.