Redis cookbook pdf download

Solution Unlike most other NoSQL solutions and key-value storage engines, Redis includes several built-in data types, allowing developers to structure their data in meaningful semantic ways. Predefined data types add the benefit of being able to perform datatype specific operations inside Redis, which is typically faster than processing the data externally.

In this section, we will look at the data types Redis supports, and some of the thinking behind them. Discussion Unlike most other NoSQL solutions and key-value storage engines, Redis includes several built-in data types, allowing developers to structure their data in meaningful semantic ways—with the added benefit of being able to perform data-type specific operations inside Redis, which is typically faster than processing the data externally.

Because a key can contain any characters, you can use separators to define a namespace with a semantic value for your business. An example might be using cache:projecttasks, where the colon acts as a namespace separator.

Retrieving a key from storage requires comparison operations, so keeping keys as small as possible is a good idea. Additionally, smaller keys are more effective in terms of memory usage. This means you should design your keys in such a way that combines readability to help you and regular key sizes to help Redis.

With this in mind, keys like c:pt or user would be bad—the first because it is semantically crude, and the latter because it includes whitespace. Note that the last example of an SHA1 hash is, while hard to guess and predict, semantically meaningful and quite useful if you are storing data related to an object for which you can consistently calculate a hash.

Strings The simplest data type in Redis is a string. Strings are also the typical and frequently the sole data type in other key-value storage engines. You can store strings of any kind, including binary data. You might, for example, want to cache image data for avatars in a social network.

Lists Lists in Redis are ordered lists of binary safe strings, implemented on the idea of a linked list. This means that while getting an element by a specific index is a slow operation, adding to the head or tail of the data structure is extremely fast, as it should be in a database. Hashes Much like traditional hashtables, hashes in Redis store several fields and their values inside a specific key. Sets and Sorted Sets Sets in Redis are an unordered collection of binary-safe strings.

Elements in a given set can have no duplicates. For instance, if you try to add an element wheel to a set twice, Redis will ignore the second operation.

Sets allow you to perform typical set operations such as intersections and unions. While these might look similar to lists, their implementation is quite different and they are suited to different needs due to the different operations they make available.

Memory usage should be higher than when using lists. Sorted sets are a particular case of the set implementation that are defined by a score in addition to the typical binary-safe string. Using Redis from the Command Line Problem Often you might find yourself in need of firing a simple Redis query, either to set or change a variable, flush a database, or perhaps take a look at your data.

With Redis you can achieve this directly from the command line. Solution Redis ships with a command line client: redis-cli. Redis-cli is a fully featured interactive client, supporting line editing, history, and tab completion.

By using help followed by a Redis command, you can also get help on how each command works. You can use redis-cli to connect to a local or remote host Redis server and call commands by passing them as arguments or piping them in or by using its interactive mode. A couple of commands will get you going. Using Redis from Ruby with redis-rb Problem You want to access and manipulate data in your Redis server by using the Ruby programming language.

Discussion redis-rb is a full-fledged Redis client in Ruby created by Ezra Zygmuntowicz. In order to use it from Ruby, you should start by installing the Ruby gem with the gem install redis command. You can then use the Redis ruby gem to manipulate data in your Redis server instance. As you can see, using Redis from inside a Ruby script or full-blown application is quite trivial.

You can pass the :host and :port options to the Redis. Once these two steps are done, you are ready to start using Redis from Ruby on Rails. You could specify things like User. We could just add a column to whatever table is storing our page data in our RDBMS, but hopefully our traffic is high enough that updates to this column have trouble keeping up.

We need something much faster to update and to query. So by designing a proper namespace for our data, maintaining our counters becomes a trivial one-operation endeavor. To store our social network page visit data, we could have a key namespace such as visits:pageid:totals, which for a page ID of would look like visitstotals. If we already were storing visit data somewhere, we can first seed redis with that data by setting our keys to the current values: SET visitstotals SET visitstotals A simple pseudocode for visits and counters could look like this: 1.

The visitor requests the page. We capture the return value of the INCR command. We show the user the page with the return value. So to store information about a user called John Doe, we might build a hash called users:jdoe.

Depending on how you want to retrieve your data, you may find it useful to use HGETALL or one of these to retrieve data from Redis into your application. Sets are a natural fit for circles, because sets represent collections of data, and have native functionality to do interesting things like intersections and unions.

We want to store several circles for each of our users, so it makes sense for our key to include a bit about the user and a bit about the actual circle. Similarly, his soccer practice buddies might be listed in a set with the key circle:jdoe:soccer. While the example above works great, it may be a good idea for performance reasons to sacrifice a bit of readability for more speed and memory efficiency.

Now we have a set called circle:jdoe:family with three values in our case, these are users:anna, users:richard, and users:mike and a second one called circle:jdoe:soc cer with four values users:mike, users:adam, users:toby, and users:apollo. It also does it extremely fast, making it an ideal candidate to implement applications that require managing and doing operations with sets. Circles are one example, but things like recommendations or even text search are also good fits for sets.

Existing data is overwritten even if of a different data type. GET key Returns the content held by the key. Works only with string values. INCR key Increments the integer stored at key by 1. DECR key Decrements the integer stored at key by 1. Inspecting Your Data Problem While developing or perhaps debugging with Redis, you may find you need to take a look at your data. Use it with the supported wildcard matchers. However, that is not enough, as you still may not know what the key type is.

KEYS h? KEYS h[ae]llo Returns only the keys hallo and hello, if they exist. Keep in mind that every time you use the KEYS command, Redis has to scan all the keys in the database.

If you need a list of all your keys or a subset you might want to add those keys to a set and then query it. TYPE key-name Tells the type of the key. Possible types are: string, list, hash, set, zset, and none. These types of data will be stored in hashes, sets, and strings depending on their specific requirements and interactions.

Discussion Initial setup To start with, consumers must enter their data before they issue a request. A command should be issued all on one line.

HMSET hash-name key1 value1 [key2 value Getting a request token In order to get a request token, consumers send their key, a timestamp, a unique generated nonce, a callback url, and a request signature that is a hash of the request path and parameters using the consumer secret.

Also, we can delete all the nonces for past requests after a chosen period of time, by setting expiration times on each one. Should this happen, the provider should refuse to generate a new token.

The return value is 1 if the element is added and 0 if it was already a member. This can be used on any type of key strings, hashes, lists, sets or sorted sets and is one of the most powerful Redis features.

TTL key Tells you the remaining time to live of a key with an expiration timeout. These are obtained by submitting the consumer key, request token, and secret that were previously fetched and generating an access token. IO to quickly create a real-time chat system. When a message hits that cloud, clients that subscribe to messages of that kind will get the message.

They just need to be able to send messages in a given pattern, and receive messages that match that pattern. On the server side, Node and Socket. IO and Redis. This piece of code will take care of setting up a connection to Redis and listening on a given port for connecting clients either using websockets or flash—this choice will be handled transparently by Socket.

Create a chat. IO, this code is pretty straightforward. Latest Books. Articulate Storyline Essentials 18 June Beginning SharePoint Development 18 June Beginning SharePoint 18 June Popular Categories. Programmer-books is a great source of knowledge for software developers. Here we share with you the best software development books to read. Next, you will learn how to develop applications with Redis in Java, Python, and the Spring Boot web framework.

You will also learn replication tasks, which will help you to troubleshoot replication issues. Furthermore, you will learn the steps that need to be undertaken to ensure high availability on your cluster and during production deployment. Toward the end of the book, you will learn the topmost tasks that will help you to troubleshoot your ecosystem efficiently, along with extending Redis by using different modules.

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