[Pre-W7] Redis DB

YC Tech Academy Backend Career Project


This week's topic is Redis, an open-source, in-memory data structure store, known for its speed and flexibility. Redis serves as a database, cache, and message broker, supporting various data structures such as strings, hashes, lists, sets, and sorted sets with range queries. It's a versatile tool that can be used for a wide array of applications, from caching to session management, real-time analytics, and more.

Stay tuned as we explore the intricacies of Redis and how it can be leveraged to enhance your application's performance and scalability.


Redis operates entirely in-memory, which allows it to process data extremely fast compared to disk-based databases. This makes it an ideal choice for scenarios where rapid access to data is crucial, such as in gaming leaderboards, session caching in web applications, or as a queue for background jobs in a distributed system.

One of the key features of Redis is its support for atomic operations on these data types, enabling complex operations to be executed in a single step, which is a cornerstone for developing high-performance applications. Its simplicity in setup and model for key-value storage allows developers to implement solutions without the overhead of traditional database systems.

Moreover, Redis's replication, Lua scripting, and various levels of on-disk persistence, and support for multiple levels of clustering make it a robust choice for building scalable, high-availability applications.

Data types

Redis is renowned for being an open-source, in-memory data structure store, and it serves as a versatile database, cache, and message broker. Let's dive into the variety of native data types Redis offers to solve an array of problems effectively.

Core Data Types

  • Strings: Redis strings are basic data types that can store a sequence of bytes, functioning as the most elementary form of storing data, from simple text to complex serialized data structures.

  • Lists: These are simply lists of strings sorted by insertion order, making them ideal for implementing queues or stacks where the order of elements is crucial.

  • Sets: Sets are collections of unique strings that enable you to add, remove, and test for the existence of elements in constant time, ideal for managing unique items.

  • Hashes: They are collections of field-value pairs, similar to dictionaries in Python or HashMaps in Java, suitable for representing objects with multiple attributes.

  • Sorted Sets: Unique strings where each member is associated with a score, allowing them to be sorted, which is perfect for leaderboards or sorted retrieval operations.

  • Streams: This data structure is like an append-only log suitable for recording sequences of events or messages over time, facilitating complex stream processing.

  • Geospatial Indexes: They enable you to perform geospatial operations, such as calculating distances or finding all items within a geographical radius.

  • Bitmaps: Bitmaps allow for efficient storage and manipulation of binary data, offering a unique approach to handling arrays of bits.

  • Bitfields: This feature allows you to perform atomic operations on an array of bits within a string, enabling efficient encoding of multiple counters or flags.

  • HyperLogLog: HyperLogLog provides an efficient way to estimate the cardinality of a set, which is particularly useful for counting unique elements in a large dataset.

Extensions and Advanced Use Cases

To amplify the capabilities provided by native data types, you can utilize Lua scripting for custom server-side operations, Redis modules for expanding its functionalities, or Redis Stack for advanced features like JSON support and time series data management. These tools significantly enhance Redis's utility, allowing it to handle a broad spectrum of use cases with ease.

Getting Started

Redis, an acronym for Remote Dictionary Server, is a powerful in-memory data structure store used as a database, cache, and message broker. If you're new to Redis, here's how you can get started with setting up and using this versatile tool.


The simplest way to begin using Redis is by signing up for Redis Cloud. Here’s how you can set it up:

  1. Create a free account on Redis Cloud.

  2. Create a free database by following the provided instructions.

Alternatively, if you prefer to work locally, you can install Redis on your local machine by following the installation guides available in the official documentation.


Once Redis is installed or set up in the cloud, the next step is to establish a connection. If you're using Redis running locally, connect to the server using the following command in the Redis CLI:

redis-cli -h -p 6379

If you are connecting to a Redis Cloud instance, the connection details can be copied from the Redis Cloud database configuration page. An example connection string might look like this:


The format for the connection string is host:port. Remember to use the username and password for your Redis Cloud database. You can pass these credentials directly to your client or use the AUTH command after establishing the connection.

Store and Retrieve Data

Redis allows you to use familiar data types from your local programming environment in a server-side context.

  • Strings: For example, Redis strings can store anything from text to binary data. To set and get a string value:

      SET bike:1 "Process 134"
      GET bike:1
  • Hashes: Hashes work like dictionaries or hash maps and can be used to represent objects or store groups of counters. Here’s how you can manipulate hashes:

      HSET bike:1 model Deimos brand Ergonom type 'Enduro bikes' price 4972
      HGET bike:1 model
      HGET bike:1 price
      HGETALL bike:1

For a comprehensive guide on the various data types Redis supports, you can refer to the data types section in the documentation. Each data type comes with its set of commands for data manipulation and retrieval, thoroughly explained in the commands reference.

Scan the Keyspace

Redis stores each item with a unique key within its keyspace. You can explore the keyspace using the SCAN command, which is particularly useful for retrieving keys with a specific pattern. For instance, to scan for the first 100 keys with the prefix "bike:":

SCAN 0 MATCH "bike:*" COUNT 100

SCAN provides a cursor that you can use iteratively to retrieve subsequent batches of keys until the cursor returns a value of 0, indicating the end of the keyspace.

With these initial steps, you're now ready to embark on your Redis journey, unlocking the potential of rapid, in-memory data operations that can significantly enhance the performance and efficiency of your applications.

Search and Query in Redis

Redis, traditionally known for its key-value store capabilities, has significantly enhanced its functionalities with Redis Stack, introducing advanced search and querying features. Redis Stack enriches the Redis experience by offering secondary indexing, full-text search, and even vector similarity search, among other capabilities.

Query Syntax

Redis Stack's query syntax is intuitive yet powerful, supporting a wide range of search criteria:

  • Basic Syntax: Simple tokens like foo bar imply an intersection (AND), while a pipe character (|) like hello|hallo indicates a union (OR). Exact phrases are quoted, "hello world".

  • Negation: Exclude terms using a minus symbol (-), such as hello -world.

  • Prefix/Infix/Suffix Matches: Use an asterisk (*) like hel* for prefix matches. For infix or suffix matches, use * on both sides, like *sun*.

  • Field Modifiers: Use @field: to target specific fields, for example, @name:James.

  • Numeric Filters: Specify ranges with square brackets, @price:[100 200].

  • Geo Filters: Query by geographical radius using syntax like @location:[-122.41 37.77 5 km].

  • Polygon Search: Use geospatial capabilities to query against shapes like POINT or POLYGON.

  • Vector Similarity Search: Include vector similarity in queries with syntax like @vector_field:[VECTOR_RANGE 0.5 $query_vec].

  • Prefix Matching: Redis allows for matching all terms starting with a given prefix, adding * to a prefix token.

  • Wildcard Matching: Use wildcard characters like ? and * for matching patterns within strings.

  • Fuzzy Matching: Surround terms with % for fuzzy matching based on Levenshtein distance.

Primary Features of Redis Stack

  • Secondary Indexing: Beyond primary key-based access, Redis Stack allows you to create secondary indexes on your data, enabling more complex queries.

  • Full-text Indexing: Index multiple fields in a document for full-text search, allowing users to perform sophisticated text-based searches.

  • Incremental Indexing: New data is indexed incrementally without impacting performance, ensuring that your indexes are always up-to-date.

  • Boolean Queries: Combine subqueries with AND, OR, and NOT operators to refine search results.

  • Prefix-based Searches and Auto-complete: Implement efficient prefix-based searches and auto-complete suggestions for user input.

  • Phrase and Slop-based Search: Search for exact phrases or use slop to find matches with words in proximity.

  • Stemming: Utilize stemming-based query expansion to enhance search capabilities across various languages.

  • Numeric Filters and Ranges: Query numeric fields using filters and ranges for precise searches.

  • Geo-filtering: Integrate with Redis geo commands to filter search results based on geographic data.

  • Vector Similarity Search: Perform semantic searches using exact and approximate algorithms for vector similarity.

  • Unicode Support: Redis Stack supports Unicode, requiring UTF-8 input for accurate processing.

  • Document Management: Retrieve full document contents or IDs, and manage document deletion and updates while handling index garbage collection efficiently.

JSON Documents and Redis Stack

Redis Stack extends its indexing and querying features to JSON documents. When JSON support is combined with Redis Stack, you can index and execute queries against JSON documents, enhancing the ability to interact with complex data structures natively stored in Redis.

Cluster Support and Scalability

Redis Stack's search and querying features are fully compatible with distributed databases. This ensures that Redis can scale to handle billions of documents and operate seamlessly across hundreds of servers, making it a robust solution for large-scale applications.

Commercial Support

Redis Ltd. offers commercial support for Redis Stack, ensuring that enterprises can rely on professional assistance and services. For more details, businesses are encouraged to reach out via the Redis Ltd. website.

Supported Platforms

Redis Stack is primarily developed and tested on Linux and macOS operating systems for x86_64 CPUs. It is important to note that Atom CPUs are not currently supported.


As we conclude this exploration of Redis and Redis Stack, we've witnessed the robust capabilities of this powerful in-memory data structure store. From its atomic operations on various data types to its advanced search and query functionalities with Redis Stack, Redis proves to be an indispensable tool for developers aiming to enhance their applications' performance and scalability.

Redis not only accelerates data processing with its in-memory architecture but also simplifies complex data interactions through intuitive search and querying syntax. Its commitment to continuous improvement and scalability, supported by Redis Ltd.'s commercial backing, assures a future-proof investment for businesses looking to leverage real-time data processing.

By embracing Redis and its extended features, developers can construct highly responsive, data-intensive applications capable of handling the demands of modern digital ecosystems. Whether you're implementing caching mechanisms, managing sessions, or performing intricate data analytics, Redis offers the flexibility and efficiency to meet and exceed your application development needs.

As we bid farewell, we encourage you to embark on your Redis journey, confident in the knowledge that this versatile platform will support and elevate your data management strategies to new heights. Redis is more than just a tool; it's a gateway to unlocking potential, fostering innovation, and driving success in an ever-evolving technological landscape. Thank you for joining us on this insightful journey into Redis, and we look forward to seeing the remarkable solutions you'll build with this dynamic powerhouse at your disposal.