Sidekiq: How to check the maximum client Redis database size

You can check the maximum client Redis database size in Sidekiq with this command.

CopySidekiq.redis { |redis| puts redis.info.fetch('maxmemory_human') }
#=> 512.00M

If you just want the maximum database size for a known Redis database URL you can use the Redis Ruby client Show archive.org snapshot or the Redis CLI:

Redis database size via Ruby client

Copyirb(main):002> Redis.new(url: 'redis://localhost:16380/1').info.fetch('maxmemory_human')
=> "512.00M"

Redis database size via CLI

Copy$ redis-cli --port 16380 --database 1 INFO memory | grep maxmemory_human
maxmemory_human:512.00M

Memory footprint

If you want to calculate the estimated Redis memory usage of a job, you can measure the consumed memory usage before and after the job was enqueued. For a simple job like Foo.perform_async(1) the memory footprint is around 508 bytes. Here is a short table to get an overview about an estimated memory footprint with many jobs enqueued.