Data type is the core concept when it comes to application design and development with Redis. Unlike RDBMS, there is no table or schema you need to worry about in Redis. When it comes to how to organize your data in Redis, the one thing you should consider first is what data types natively supported by Redis fit your scenario best. Moreover, you have no way to manipulate your data in Redis with SQL, as in a relational database. Instead, you issue commands directly on the target data with the API, accompanied by the data. Therefore, another thing you need to think about is whether the operations of a certain data type in Redis can satisfy your business requirements.

In this chapter, we will look at all data types and important operations related to Redis. In order to better illustrate the data types and their operations, a Yelp-like demo application (we'll call...

The string type is the most common and useful data type in programming languages and applications. It is also the fundamental data type of Redis, in which all keys must be strings. This recipe demonstrates the basic commands to manipulate strings in Redis.

You need to finish the installation of the Redis Server, as we described in the Downloading and installing Redis recipe in Chapter 1, Getting Started with Redis, and connect to the Redis Server by redis-cli.

To understand how to use the string data type...

The list data type is a very useful type in application development, as a list stores a sequence of objects, and can be also used as a stack or queue. In Redis, the value associated with a key can be a list of strings. A list in Redis is more like a doubly linked list in the data structure world. This recipe demonstrates the basic commands to manipulate lists in Redis.

You need to finish the installation of the Redis Server, as we described in the Downloading and installing Redis recipe in Chapter 1, Getting Started with Redis, and connect to the Redis Server by redis-cli.

The hash data type represents mapping relationships between fields and values, just like maps or dictionaries in some programming languages. The Redis dataset itself can be viewed as a hash, where keys of strings are mapped to data objects such as strings and lists, as we have seen in the previous two recipes. The data objects of Redis can again use hashes, whose fields and values must be strings. To distinguish from Redis keys, we use fields to denote keys in Redis hash-value objects. The hash is a perfect data type for storing an object's properties. In this recipe, we will use hashes to store restaurants' information, such as address, phone number, rating, and so on.

The set data type is a collection of unique and unordered objects. It is often used in applications for membership testing, duplicates removal, and math operations (union, intersection, and difference). Redis value objects can be string set. In this recipe, we will store restaurants' tags in a Redis set and demonstrate basic commands Redis provides to manipulate a set.

You need to finish the installation of the Redis Server, as we described in the Downloading and installing Redis recipe in Chapter 1, Getting Started with Redis, and connect to the Redis Server by redis-cli.

Compared to the data type set introduced in the previous recipe, sorted list is a similar but more complex one in Redis. The word Sorted means each element in this kind of set owns a weight that can be used for sorting, and you can retrieve the elements from the set in order. It's convenient to take advantage of this natively sorted feature in some scenarios for which the sorting is needed all the time. In this recipe, we'll see how to manipulate sorted set.

You need to finish the installation of the Redis Server, as we described in the Downloading and installing Redis recipe in Chapter 1, Getting Started with Redis, and connect to the Redis Server by redis...

Counting distinct values is a common task in various kinds of daily data processing scenarios. In Redis, while it's fine and sometimes necessary to implement distinct counting using set, memory consumption and performance degradation should be taken into consideration when the size of the set increases to tens of millions. If you don't need to retrieve the content of the data set and just want a unique counting value, one thing you can do is to use the HyperLogLog (HLL) data type in Redis to optimize the memory and performance issues caused by the set. In this recipe, we'll cover how to use HLL in Redis.

You need to finish the installation of the Redis Server...

Location-based service has gained in popularity as smartphones have become increasingly more common. The Geo API has been introduced officially in Redis, since Release 3.2, to support storing and querying geospatial coordinates for these location-related scenarios. In this recipe, we will explore the Geo data type in Redis.

You need to finish the installation of the Redis Server, as we described in the Downloading and installing Redis recipe in Chapter 1, Getting Started with Redis, and connect to the Redis Server by redis-cli.