What is Redis Cache?
Redis is a high-performance, in-memory data structure store. It’s often used as a cache (hence the name), but it can also be used to store other types of information, such as session data and user preferences. Redis works by storing key-value pairs in memory, which allows for fast lookups and updates.
This makes Redis ideal for storing frequently accessed data that hasn’t changed since the last time you looked at it, like user profiles or page titles on your website, and then using this information when generating dynamic content from templates or APIs such as Facebook Instant Articles (FIA). Think of Redis Cache as a cache server, similar to Memcached or Varnish. However, unlike those other tools, Redis Cache also provides data structures and commands that allow you to store more complex information than simple key-value pairs.
How does Redis cache work?
Redis Cache works by storing data in memory. When you request data from Redis Cache, it checks to see if the data is already in memory. If the data is in memory, Redis Cache returns it immediately. If the data is not in memory, Redis Cache retrieves it from the source and stores it in memory. The next time the data is requested, Redis Cache will return it from memory. It can also be configured to expire data after a certain amount of time. This is useful for data that changes frequently or data that is only needed for a short period of time. When data expires, Redis Cache will remove it from memory.
Redis speeds up websites by reducing the amount of time it takes to access frequently requested data. Redis Cache is designed to store and retrieve data quickly and efficiently. It can be used to cache database queries, API responses, or any other type of data that is accessed frequently.
Why use Redis Cache?
- Speed: Redis Cache can help to speed up your applications by reducing the amount of time it takes to access frequently requested data. Because Redis Cache stores data in memory, it can return data much faster than traditional disk-based storage solutions.
- Scalability: Redis Cache is highly scalable. You can add more servers to your Redis Cache cluster to increase capacity as needed.
- Performance: Redis Cache is designed to be highly performant. It can handle a large number of requests per second with very low latency.
- Flexibility: Redis Cache is a very flexible caching solution. It can be used to cache any type of data, from simple key-value pairs to more complex data structures.
- Reliability: Redis Cache is highly available and reliable. It can be configured to replicate data across multiple servers to ensure that data is always available, even if a server fails.
Redis vs Memcached
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Feature
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Redis Cache
 |
Memcached
 |
|---|---|---|
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Data storage
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In-memory key-value store
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In-memory key-value store
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Data structures
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Supports strings, hashes, lists, sets, sorted sets, and more
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Supports key-value pairs
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Querying
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Supports simple queries and indexing
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Does not support querying
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|
Replication
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Supports master-slave and cluster replication
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Supports multi-node replication
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Scalability
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Highly scalable with support for sharding
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Highly scalable with support for sharding
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|
Integration
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Integrates with a wide range of programming languages and frameworks
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Integrates with a wide range of programming languages and frameworks
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Use cases
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Caching, real-time analytics, pub/sub messaging
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Caching, session management
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Data Structures: Redis Cache supports a wider range of data structures than Memcached, including strings, hashes, lists, sets, sorted sets, and more. This makes Redis Cache more versatile and flexible in terms of what types of data it can store and how it can be manipulated.
Persistence: Redis Cache supports persistence, meaning that data can be stored to disk and retrieved later, even after a server restart. This can be useful for applications that need to maintain data integrity or have long-term storage needs.
Advanced features: Redis Cache provides several advanced features, such as Lua scripting, transactions, and pub/sub messaging, that are not available in Memcached. These features can be used to build more complex and sophisticated applications.
Performance: In certain use cases, Redis Cache may outperform Memcached in terms of latency and throughput. This is especially true for applications that require more complex operations, such as sorting or range queries, which Redis Cache can perform faster than Memcached.
However, Memcached also has its own advantages. It’s simpler and easier to use than Redis Cache, and it’s optimized for storing and retrieving key-value pairs quickly and efficiently. Additionally, Memcached is often used in conjunction with other caching solutions like Redis Cache to achieve optimal performance and scalability.
How to test if you have Redis Cache enabled
In order for Redis Cache to work it has to be installed on your server. The first step is to check if your web host offers Redis Cache. To check for yourself, log in to your server using SSH and with a terminal or command prompt do the following.
- Run redis-cli If the command returns the Redis prompt (127.0.0.1:6379>), Redis is installed.
- You can also run redis-cli ping and you will get the response “PONG”
On a2Hosting Redis Cache is installed by default, and activating it is as simple as a checkbox.
You can then connect the Redis Extension in the LiteSpeed Plugin and test if Redis is running this easilly.
Redis Cache is free and open source. There are paid plans for Redis Cache, but they’re not necessary if you want to use the service for personal projects or small businesses.
Redis Cache providers offer different pricing models, so it’s important to compare them before choosing a provider.
On a2Hosting Redis Cache is installed by default
