In early 2016, we introduced the ability to view the Redis slow log in the Compose console. For 2017, we thought we'd make it a little more noticeable.
The Redis slow log records any commands which took longer than a particular time to execute. Redis is single threaded, so a task which keeps the Redis engine busy is also blocking other users requests from being processed. Being fast is important for Redis queries, so the Redis developers built in a slow log system to record those time-consuming calls. There's commands to set it up and browse it. Compose's slow log feature exposes those built-in to Redis slow logging capabilities to the Compose user without them having to send commands to their Redis database.
But there's a thing about logs; you often never look at them till you know there's a problem and when you do look at them, you usually can spot where a particular problem started growing and wish that you'd known to look then. Well, now the Compose console will let you know if there have been recent slow log additions. It does this in two places; first, in the summary:
And also in the topology overview of the cluster:
The warning is an amber warning and not a critical alert because we understand that you may be purposely running complex queries on your database but we still want to warn you. If these slow log additions are unexpected, just click on the Slow Log option in the sidebar and you can check out what caused them.
We're hoping this will add to the opportunities to give you an early warning of potential problems with your Redis data store and let you make changes to keep things blazingly fast.
If you have any feedback about this or any other Compose article, drop the Compose Articles team a line at firstname.lastname@example.org. We're happy to hear from you.