"\u0004\bo: means that you can store any serializable Ruby object, like results of an ActiveRecord query. You can also store something in the cache: Then Rails will use Redis for all its caching needs. Since Rails 5.2 you can use Redis as your cache store.Ĭonfig.cache_store = :redis_cache_store, If you’d like Redis persistence to behave more like a SQL database, you can enable the “Append Only Mode”, which will save changes after every second.Įnable this mode by adding (or uncommenting) this line on the redis configuration: This creates a dump.rdb file on the current directory. after 1 min, if 10,000 or more keys changed.after 5 min, if 10 or more keys changed.after 15 min, if 1 or more keys changed.It only saves data to disk when you stop the server. Data Persistence in Redisīy default Redis doesn’t save every single operation you make like a regular database. Nothing special about this convention, for Redis (the software) a key with a colon is no different than a key without it, but for you (a friendly Ruby developer) it helps you organize your data. One common convention is to use a colon ( :) to separate the generic name & the specific part of that name. There are no columns, there are no tables, everything is one plain namespace. Please read the documentation for more set operations. If you use “zrange” you’ll get the items in ascending order.Īnother thing you can do is build a fast autocomplete engine with the ZRANGEBYLEX command. Notice the “rev” part in “zrevrange”, that means reverse & it will give you the items in descending order. “Starting from the highest rank (0), give me the top item.” Now that we have our set, we can query for the top item: Redis.zadd("popular_fruit", 30, "orange") Redis.zadd("popular_fruit", 20, "banana") You can query to get the top N items in this set. The value is called a “score” in the Redis documentation. This allows you to create a list of unique items that are sorted by a given value. Redis is not limited to simple key/value storage. Have fun exploring & trying out other commands! How to Use Sorted Sets in Redis Where the 2nd argument is seconds before this key will expire, and the last argument is the value for this key. Or you can set an auto-expiring key with setex: You can type the name of a specific command, or search by data structure.Ĭlick on “Filter by group” & choose “Strings”, then pick one of the commands to test it out.įor example, you can use the incr command: This gem does a good job at mapping Ruby methods to Redis commands, so if you want to know what commands are available you can check the Redis documentation, or you can check the gem documentation. Let’s start by adding one key, a, with a value of 1. With the gem installed, you can connect to your Redis server & start working with it. You can interact with Redis directly using redis-cli, but if you want to work with Redis from Ruby you should use a gem.īut only one is officially recommended by the Redis developers, redis-rb. Now you’re ready to start using Redis! Using Redis Gems Note: You may have to run redis-server on another terminal to start the server before you can connect to it. Once the server is up & running you’ll be able to use redis-cli to connect to the server. If you’re running Ubuntu, you can use apt install redis-server, on Mac you can use brew install redis & on Windows 10 you’ll need the “Windows Subsystem for Linux” ( click for instructions). Just like you would install any other database. Let’s have a look at how you can use Redis in your Ruby applications! Installing Redis Locally It has nothing to do with your typical SQL database, like Postgres. Redis is a kind of in-memory database that has different kinds of data structures you can use.
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