# Redis sets ```json metadata { "schema_version": 2, "title": "Redis sets", "description": "Introduction to Redis sets", "categories": ["docs","develop","stack","oss","rs","rc","oss","kubernetes","clients"], "tableOfContents": {"sections":[{"id":"examples","title":"Examples"},{"id":"tutorial","title":"Tutorial"},{"id":"limits","title":"Limits"},{"id":"performance","title":"Performance"},{"id":"alternatives","title":"Alternatives"},{"id":"learn-more","title":"Learn more"}]} , "codeExamples": [{"codetabsId":"sets_tutorial-stepsadd","commands":[{"acl_categories":["@write","@set","@fast"],"complexity":"O(1)","name":"SADD"}],"description":"Foundational: Add members to a set using SADD when you need to store unique items (duplicates are silently ignored)","difficulty":"beginner","id":"sadd","languages":[{"id":"redis-cli","panelId":"panel_redis-cli_sets_tutorial-stepsadd"},{"clientId":"redis-py","clientName":"redis-py","id":"Python","langId":"python","panelId":"panel_Python_sets_tutorial-stepsadd"},{"id":"Node-js","panelId":"panel_Nodejs_sets_tutorial-stepsadd"},{"clientId":"jedis","clientName":"Jedis","id":"Java-Sync","langId":"java","panelId":"panel_Java-Sync_sets_tutorial-stepsadd"},{"clientId":"lettuce","clientName":"Lettuce","id":"Java-Async","langId":"java","panelId":"panel_Java-Async_sets_tutorial-stepsadd"},{"clientId":"lettuce","clientName":"Lettuce","id":"Java-Reactive","langId":"java","panelId":"panel_Java-Reactive_sets_tutorial-stepsadd"},{"clientId":"go-redis","clientName":"go-redis","id":"Go","langId":"go","panelId":"panel_Go_sets_tutorial-stepsadd"},{"id":"dotnet-Sync (SE-Redis)","panelId":"panel_Csharp-Sync (SERedis)_sets_tutorial-stepsadd"},{"clientId":"predis","clientName":"Predis","id":"PHP","langId":"php","panelId":"panel_PHP_sets_tutorial-stepsadd"},{"clientId":"redis-rb","clientName":"redis-rb","id":"Ruby","langId":"ruby","panelId":"panel_Ruby_sets_tutorial-stepsadd"},{"clientId":"redis-rs","clientName":"redis-rs","id":"Rust-Sync","langId":"rust","panelId":"panel_Rust-Sync_sets_tutorial-stepsadd"},{"clientId":"redis-rs","clientName":"redis-rs","id":"Rust-Async","langId":"rust","panelId":"panel_Rust-Async_sets_tutorial-stepsadd"}]},{"buildsUpon":["sadd"],"codetabsId":"sets_tutorial-stepsismember","commands":[{"acl_categories":["@read","@set","@fast"],"complexity":"O(1)","name":"SISMEMBER"}],"description":"Foundational: Test set membership using SISMEMBER when you need O(1) lookups (much faster than checking a list)","difficulty":"beginner","id":"sismember","languages":[{"id":"redis-cli","panelId":"panel_redis-cli_sets_tutorial-stepsismember"},{"clientId":"redis-py","clientName":"redis-py","id":"Python","langId":"python","panelId":"panel_Python_sets_tutorial-stepsismember"},{"id":"Node-js","panelId":"panel_Nodejs_sets_tutorial-stepsismember"},{"clientId":"jedis","clientName":"Jedis","id":"Java-Sync","langId":"java","panelId":"panel_Java-Sync_sets_tutorial-stepsismember"},{"clientId":"lettuce","clientName":"Lettuce","id":"Java-Async","langId":"java","panelId":"panel_Java-Async_sets_tutorial-stepsismember"},{"clientId":"lettuce","clientName":"Lettuce","id":"Java-Reactive","langId":"java","panelId":"panel_Java-Reactive_sets_tutorial-stepsismember"},{"clientId":"go-redis","clientName":"go-redis","id":"Go","langId":"go","panelId":"panel_Go_sets_tutorial-stepsismember"},{"id":"dotnet-Sync (SE-Redis)","panelId":"panel_Csharp-Sync (SERedis)_sets_tutorial-stepsismember"},{"clientId":"predis","clientName":"Predis","id":"PHP","langId":"php","panelId":"panel_PHP_sets_tutorial-stepsismember"},{"clientId":"redis-rb","clientName":"redis-rb","id":"Ruby","langId":"ruby","panelId":"panel_Ruby_sets_tutorial-stepsismember"},{"clientId":"redis-rs","clientName":"redis-rs","id":"Rust-Sync","langId":"rust","panelId":"panel_Rust-Sync_sets_tutorial-stepsismember"},{"clientId":"redis-rs","clientName":"redis-rs","id":"Rust-Async","langId":"rust","panelId":"panel_Rust-Async_sets_tutorial-stepsismember"}]},{"buildsUpon":["sadd"],"codetabsId":"sets_tutorial-stepsinter","commands":[{"acl_categories":["@read","@set","@slow"],"complexity":"O(N*M)","name":"SINTER"}],"description":"Set intersection: Find common members across multiple sets using SINTER when you need to identify shared items (e.g., users in multiple groups)","difficulty":"intermediate","id":"sinter","languages":[{"id":"redis-cli","panelId":"panel_redis-cli_sets_tutorial-stepsinter"},{"clientId":"redis-py","clientName":"redis-py","id":"Python","langId":"python","panelId":"panel_Python_sets_tutorial-stepsinter"},{"id":"Node-js","panelId":"panel_Nodejs_sets_tutorial-stepsinter"},{"clientId":"jedis","clientName":"Jedis","id":"Java-Sync","langId":"java","panelId":"panel_Java-Sync_sets_tutorial-stepsinter"},{"clientId":"lettuce","clientName":"Lettuce","id":"Java-Async","langId":"java","panelId":"panel_Java-Async_sets_tutorial-stepsinter"},{"clientId":"lettuce","clientName":"Lettuce","id":"Java-Reactive","langId":"java","panelId":"panel_Java-Reactive_sets_tutorial-stepsinter"},{"clientId":"go-redis","clientName":"go-redis","id":"Go","langId":"go","panelId":"panel_Go_sets_tutorial-stepsinter"},{"id":"dotnet-Sync (SE-Redis)","panelId":"panel_Csharp-Sync (SERedis)_sets_tutorial-stepsinter"},{"clientId":"predis","clientName":"Predis","id":"PHP","langId":"php","panelId":"panel_PHP_sets_tutorial-stepsinter"},{"clientId":"redis-rb","clientName":"redis-rb","id":"Ruby","langId":"ruby","panelId":"panel_Ruby_sets_tutorial-stepsinter"},{"clientId":"redis-rs","clientName":"redis-rs","id":"Rust-Sync","langId":"rust","panelId":"panel_Rust-Sync_sets_tutorial-stepsinter"},{"clientId":"redis-rs","clientName":"redis-rs","id":"Rust-Async","langId":"rust","panelId":"panel_Rust-Async_sets_tutorial-stepsinter"}]},{"buildsUpon":["sadd"],"codetabsId":"sets_tutorial-stepscard","commands":[{"acl_categories":["@read","@set","@fast"],"complexity":"O(1)","name":"SCARD"}],"description":"Foundational: Get the cardinality of a set using SCARD when you need to count unique items efficiently","difficulty":"beginner","id":"scard","languages":[{"id":"redis-cli","panelId":"panel_redis-cli_sets_tutorial-stepscard"},{"clientId":"redis-py","clientName":"redis-py","id":"Python","langId":"python","panelId":"panel_Python_sets_tutorial-stepscard"},{"id":"Node-js","panelId":"panel_Nodejs_sets_tutorial-stepscard"},{"clientId":"jedis","clientName":"Jedis","id":"Java-Sync","langId":"java","panelId":"panel_Java-Sync_sets_tutorial-stepscard"},{"clientId":"lettuce","clientName":"Lettuce","id":"Java-Async","langId":"java","panelId":"panel_Java-Async_sets_tutorial-stepscard"},{"clientId":"lettuce","clientName":"Lettuce","id":"Java-Reactive","langId":"java","panelId":"panel_Java-Reactive_sets_tutorial-stepscard"},{"clientId":"go-redis","clientName":"go-redis","id":"Go","langId":"go","panelId":"panel_Go_sets_tutorial-stepscard"},{"id":"dotnet-Sync (SE-Redis)","panelId":"panel_Csharp-Sync (SERedis)_sets_tutorial-stepscard"},{"clientId":"predis","clientName":"Predis","id":"PHP","langId":"php","panelId":"panel_PHP_sets_tutorial-stepscard"},{"clientId":"redis-rb","clientName":"redis-rb","id":"Ruby","langId":"ruby","panelId":"panel_Ruby_sets_tutorial-stepscard"},{"clientId":"redis-rs","clientName":"redis-rs","id":"Rust-Sync","langId":"rust","panelId":"panel_Rust-Sync_sets_tutorial-stepscard"},{"clientId":"redis-rs","clientName":"redis-rs","id":"Rust-Async","langId":"rust","panelId":"panel_Rust-Async_sets_tutorial-stepscard"}]},{"buildsUpon":["sadd"],"codetabsId":"sets_tutorial-stepsadd_smembers","commands":[{"acl_categories":["@keyspace","@write","@slow"],"complexity":"O(N)","name":"DEL"},{"acl_categories":["@write","@set","@fast"],"complexity":"O(1)","name":"SADD"},{"acl_categories":["@read","@set","@slow"],"complexity":"O(N)","name":"SMEMBERS"}],"description":"Foundational: Retrieve all members from a set using SMEMBERS when you need the complete set (note: order is not guaranteed)","difficulty":"beginner","id":"sadd_smembers","languages":[{"id":"redis-cli","panelId":"panel_redis-cli_sets_tutorial-stepsadd_smembers"},{"clientId":"redis-py","clientName":"redis-py","id":"Python","langId":"python","panelId":"panel_Python_sets_tutorial-stepsadd_smembers"},{"id":"Node-js","panelId":"panel_Nodejs_sets_tutorial-stepsadd_smembers"},{"clientId":"jedis","clientName":"Jedis","id":"Java-Sync","langId":"java","panelId":"panel_Java-Sync_sets_tutorial-stepsadd_smembers"},{"clientId":"lettuce","clientName":"Lettuce","id":"Java-Async","langId":"java","panelId":"panel_Java-Async_sets_tutorial-stepsadd_smembers"},{"clientId":"lettuce","clientName":"Lettuce","id":"Java-Reactive","langId":"java","panelId":"panel_Java-Reactive_sets_tutorial-stepsadd_smembers"},{"clientId":"go-redis","clientName":"go-redis","id":"Go","langId":"go","panelId":"panel_Go_sets_tutorial-stepsadd_smembers"},{"id":"dotnet-Sync (SE-Redis)","panelId":"panel_Csharp-Sync (SERedis)_sets_tutorial-stepsadd_smembers"},{"clientId":"predis","clientName":"Predis","id":"PHP","langId":"php","panelId":"panel_PHP_sets_tutorial-stepsadd_smembers"},{"clientId":"redis-rb","clientName":"redis-rb","id":"Ruby","langId":"ruby","panelId":"panel_Ruby_sets_tutorial-stepsadd_smembers"},{"clientId":"redis-rs","clientName":"redis-rs","id":"Rust-Sync","langId":"rust","panelId":"panel_Rust-Sync_sets_tutorial-stepsadd_smembers"},{"clientId":"redis-rs","clientName":"redis-rs","id":"Rust-Async","langId":"rust","panelId":"panel_Rust-Async_sets_tutorial-stepsadd_smembers"}]},{"buildsUpon":["sismember"],"codetabsId":"sets_tutorial-stepsmismember","commands":[{"acl_categories":["@keyspace","@write","@slow"],"complexity":"O(N)","name":"DEL"},{"acl_categories":["@write","@set","@fast"],"complexity":"O(1)","name":"SADD"},{"acl_categories":["@read","@set","@fast"],"complexity":"O(1)","name":"SISMEMBER"},{"acl_categories":["@read","@set","@fast"],"complexity":"O(N)","name":"SMISMEMBER"}],"description":"Batch membership checks: Test multiple items at once using SMISMEMBER when you need to reduce round trips to the server","difficulty":"intermediate","id":"smismember","languages":[{"id":"redis-cli","panelId":"panel_redis-cli_sets_tutorial-stepsmismember"},{"clientId":"redis-py","clientName":"redis-py","id":"Python","langId":"python","panelId":"panel_Python_sets_tutorial-stepsmismember"},{"id":"Node-js","panelId":"panel_Nodejs_sets_tutorial-stepsmismember"},{"clientId":"jedis","clientName":"Jedis","id":"Java-Sync","langId":"java","panelId":"panel_Java-Sync_sets_tutorial-stepsmismember"},{"clientId":"lettuce","clientName":"Lettuce","id":"Java-Async","langId":"java","panelId":"panel_Java-Async_sets_tutorial-stepsmismember"},{"clientId":"lettuce","clientName":"Lettuce","id":"Java-Reactive","langId":"java","panelId":"panel_Java-Reactive_sets_tutorial-stepsmismember"},{"clientId":"go-redis","clientName":"go-redis","id":"Go","langId":"go","panelId":"panel_Go_sets_tutorial-stepsmismember"},{"id":"dotnet-Sync (SE-Redis)","panelId":"panel_Csharp-Sync (SERedis)_sets_tutorial-stepsmismember"},{"clientId":"predis","clientName":"Predis","id":"PHP","langId":"php","panelId":"panel_PHP_sets_tutorial-stepsmismember"},{"clientId":"redis-rb","clientName":"redis-rb","id":"Ruby","langId":"ruby","panelId":"panel_Ruby_sets_tutorial-stepsmismember"},{"clientId":"redis-rs","clientName":"redis-rs","id":"Rust-Sync","langId":"rust","panelId":"panel_Rust-Sync_sets_tutorial-stepsmismember"},{"clientId":"redis-rs","clientName":"redis-rs","id":"Rust-Async","langId":"rust","panelId":"panel_Rust-Async_sets_tutorial-stepsmismember"}]},{"buildsUpon":["sadd"],"codetabsId":"sets_tutorial-stepsdiff","commands":[{"acl_categories":["@keyspace","@write","@slow"],"complexity":"O(N)","name":"DEL"},{"acl_categories":["@write","@set","@fast"],"complexity":"O(1)","name":"SADD"},{"acl_categories":["@read","@set","@slow"],"complexity":"O(N)","name":"SDIFF"}],"description":"Set difference: Find members in one set but not in others using SDIFF when you need to exclude items (warning: argument order matters)","difficulty":"intermediate","id":"sdiff","languages":[{"id":"redis-cli","panelId":"panel_redis-cli_sets_tutorial-stepsdiff"},{"clientId":"redis-py","clientName":"redis-py","id":"Python","langId":"python","panelId":"panel_Python_sets_tutorial-stepsdiff"},{"id":"Node-js","panelId":"panel_Nodejs_sets_tutorial-stepsdiff"},{"clientId":"jedis","clientName":"Jedis","id":"Java-Sync","langId":"java","panelId":"panel_Java-Sync_sets_tutorial-stepsdiff"},{"clientId":"lettuce","clientName":"Lettuce","id":"Java-Async","langId":"java","panelId":"panel_Java-Async_sets_tutorial-stepsdiff"},{"clientId":"lettuce","clientName":"Lettuce","id":"Java-Reactive","langId":"java","panelId":"panel_Java-Reactive_sets_tutorial-stepsdiff"},{"clientId":"go-redis","clientName":"go-redis","id":"Go","langId":"go","panelId":"panel_Go_sets_tutorial-stepsdiff"},{"id":"dotnet-Sync (SE-Redis)","panelId":"panel_Csharp-Sync (SERedis)_sets_tutorial-stepsdiff"},{"clientId":"predis","clientName":"Predis","id":"PHP","langId":"php","panelId":"panel_PHP_sets_tutorial-stepsdiff"},{"clientId":"redis-rb","clientName":"redis-rb","id":"Ruby","langId":"ruby","panelId":"panel_Ruby_sets_tutorial-stepsdiff"},{"clientId":"redis-rs","clientName":"redis-rs","id":"Rust-Sync","langId":"rust","panelId":"panel_Rust-Sync_sets_tutorial-stepsdiff"},{"clientId":"redis-rs","clientName":"redis-rs","id":"Rust-Async","langId":"rust","panelId":"panel_Rust-Async_sets_tutorial-stepsdiff"}]},{"buildsUpon":["sinter","sdiff"],"codetabsId":"sets_tutorial-stepmultisets","commands":[{"acl_categories":["@keyspace","@write","@slow"],"complexity":"O(N)","name":"DEL"},{"acl_categories":["@write","@set","@fast"],"complexity":"O(1)","name":"SADD"},{"acl_categories":["@read","@set","@slow"],"complexity":"O(N*M)","name":"SINTER"},{"acl_categories":["@read","@set","@slow"],"complexity":"O(N)","name":"SUNION"},{"acl_categories":["@read","@set","@slow"],"complexity":"O(N)","name":"SDIFF"}],"description":"Advanced pattern: Combine SINTER, SUNION, and SDIFF to analyze complex relationships when you need to precompute set algebra across multiple datasets","difficulty":"advanced","id":"multisets","languages":[{"id":"redis-cli","panelId":"panel_redis-cli_sets_tutorial-stepmultisets"},{"clientId":"redis-py","clientName":"redis-py","id":"Python","langId":"python","panelId":"panel_Python_sets_tutorial-stepmultisets"},{"id":"Node-js","panelId":"panel_Nodejs_sets_tutorial-stepmultisets"},{"clientId":"jedis","clientName":"Jedis","id":"Java-Sync","langId":"java","panelId":"panel_Java-Sync_sets_tutorial-stepmultisets"},{"clientId":"lettuce","clientName":"Lettuce","id":"Java-Async","langId":"java","panelId":"panel_Java-Async_sets_tutorial-stepmultisets"},{"clientId":"lettuce","clientName":"Lettuce","id":"Java-Reactive","langId":"java","panelId":"panel_Java-Reactive_sets_tutorial-stepmultisets"},{"clientId":"go-redis","clientName":"go-redis","id":"Go","langId":"go","panelId":"panel_Go_sets_tutorial-stepmultisets"},{"id":"dotnet-Sync (SE-Redis)","panelId":"panel_Csharp-Sync (SERedis)_sets_tutorial-stepmultisets"},{"clientId":"predis","clientName":"Predis","id":"PHP","langId":"php","panelId":"panel_PHP_sets_tutorial-stepmultisets"},{"clientId":"redis-rb","clientName":"redis-rb","id":"Ruby","langId":"ruby","panelId":"panel_Ruby_sets_tutorial-stepmultisets"},{"clientId":"redis-rs","clientName":"redis-rs","id":"Rust-Sync","langId":"rust","panelId":"panel_Rust-Sync_sets_tutorial-stepmultisets"},{"clientId":"redis-rs","clientName":"redis-rs","id":"Rust-Async","langId":"rust","panelId":"panel_Rust-Async_sets_tutorial-stepmultisets"}]},{"buildsUpon":["sadd"],"codetabsId":"sets_tutorial-stepsrem","commands":[{"acl_categories":["@keyspace","@write","@slow"],"complexity":"O(N)","name":"DEL"},{"acl_categories":["@write","@set","@fast"],"complexity":"O(1)","name":"SADD"},{"acl_categories":["@write","@set","@fast"],"complexity":"O(N)","name":"SREM"},{"acl_categories":["@write","@set","@fast"],"name":"SPOP"},{"acl_categories":["@read","@set","@slow"],"complexity":"O(N)","name":"SMEMBERS"},{"acl_categories":["@read","@set","@slow"],"name":"SRANDMEMBER"}],"description":"Removal strategies: Use SREM for targeted removal, SPOP for random removal, or SRANDMEMBER to inspect without modifying when you need flexible deletion patterns","difficulty":"intermediate","id":"srem","languages":[{"id":"redis-cli","panelId":"panel_redis-cli_sets_tutorial-stepsrem"},{"clientId":"redis-py","clientName":"redis-py","id":"Python","langId":"python","panelId":"panel_Python_sets_tutorial-stepsrem"},{"id":"Node-js","panelId":"panel_Nodejs_sets_tutorial-stepsrem"},{"clientId":"jedis","clientName":"Jedis","id":"Java-Sync","langId":"java","panelId":"panel_Java-Sync_sets_tutorial-stepsrem"},{"clientId":"lettuce","clientName":"Lettuce","id":"Java-Async","langId":"java","panelId":"panel_Java-Async_sets_tutorial-stepsrem"},{"clientId":"lettuce","clientName":"Lettuce","id":"Java-Reactive","langId":"java","panelId":"panel_Java-Reactive_sets_tutorial-stepsrem"},{"clientId":"go-redis","clientName":"go-redis","id":"Go","langId":"go","panelId":"panel_Go_sets_tutorial-stepsrem"},{"id":"dotnet-Sync (SE-Redis)","panelId":"panel_Csharp-Sync (SERedis)_sets_tutorial-stepsrem"},{"clientId":"predis","clientName":"Predis","id":"PHP","langId":"php","panelId":"panel_PHP_sets_tutorial-stepsrem"},{"clientId":"redis-rb","clientName":"redis-rb","id":"Ruby","langId":"ruby","panelId":"panel_Ruby_sets_tutorial-stepsrem"},{"clientId":"redis-rs","clientName":"redis-rs","id":"Rust-Sync","langId":"rust","panelId":"panel_Rust-Sync_sets_tutorial-stepsrem"},{"clientId":"redis-rs","clientName":"redis-rs","id":"Rust-Async","langId":"rust","panelId":"panel_Rust-Async_sets_tutorial-stepsrem"}]}] } ``` ## Code Examples Legend The code examples below show how to perform the same operations in different programming languages and client libraries: - **Redis CLI**: Command-line interface for Redis - **C# (Synchronous)**: StackExchange.Redis synchronous client - **C# (Asynchronous)**: StackExchange.Redis asynchronous client - **Go**: go-redis client - **Java (Synchronous - Jedis)**: Jedis synchronous client - **Java (Asynchronous - Lettuce)**: Lettuce asynchronous client - **Java (Reactive - Lettuce)**: Lettuce reactive/streaming client - **JavaScript (Node.js)**: node-redis client - **PHP**: Predis client - **Python**: redis-py client - **Rust (Synchronous)**: redis-rs synchronous client - **Rust (Asynchronous)**: redis-rs asynchronous client Each code example demonstrates the same basic operation across different languages. The specific syntax and patterns vary based on the language and client library, but the underlying Redis commands and behavior remain consistent. --- ### Set command summary **19 commands in this group:** [View all set commands](https://redis.io/commands/?group=set) | Command | Summary | Complexity | Since | |---------|---------|------------|-------| | [SADD](https://redis.io/commands/sadd/) | Adds one or more members to a set. Creates the key if it doesn't exist. | O(1) for each element added, so O(N) to add N e... | 1.0.0 | | [SCARD](https://redis.io/commands/scard/) | Returns the number of members in a set. | O(1) | 1.0.0 | | [SDIFF](https://redis.io/commands/sdiff/) | Returns the difference of multiple sets. | O(N) where N is the total number of elements in... | 1.0.0 | | [SDIFFCARD](https://redis.io/commands/sdiffcard/) | Returns the number of members of the difference between the first set and all successive sets. | O(N) where N is the total number of elements in... | 8.10.0 | | [SDIFFSTORE](https://redis.io/commands/sdiffstore/) | Stores the difference of multiple sets in a key. | O(N) where N is the total number of elements in... | 1.0.0 | | [SINTER](https://redis.io/commands/sinter/) | Returns the intersect of multiple sets. | O(N*M) worst case where N is the cardinality of... | 1.0.0 | | [SINTERCARD](https://redis.io/commands/sintercard/) | Returns the number of members of the intersect of multiple sets. | O(N*M) worst case where N is the cardinality of... | 7.0.0 | | [SINTERSTORE](https://redis.io/commands/sinterstore/) | Stores the intersect of multiple sets in a key. | O(N*M) worst case where N is the cardinality of... | 1.0.0 | | [SISMEMBER](https://redis.io/commands/sismember/) | Determines whether a member belongs to a set. | O(1) | 1.0.0 | | [SMEMBERS](https://redis.io/commands/smembers/) | Returns all members of a set. | O(N) where N is the set cardinality. | 1.0.0 | #### Set command summary (part 2) | Command | Summary | Complexity | Since | |---------|---------|------------|-------| | [SMISMEMBER](https://redis.io/commands/smismember/) | Determines whether multiple members belong to a set. | O(N) where N is the number of elements being ch... | 6.2.0 | | [SMOVE](https://redis.io/commands/smove/) | Moves a member from one set to another. | O(1) | 1.0.0 | | [SPOP](https://redis.io/commands/spop/) | Returns one or more random members from a set after removing them. Deletes the set if the last member was popped. | Without the count argument O(1), otherwise O(N)... | 1.0.0 | | [SRANDMEMBER](https://redis.io/commands/srandmember/) | Get one or multiple random members from a set | Without the count argument O(1), otherwise O(N)... | 1.0.0 | | [SREM](https://redis.io/commands/srem/) | Removes one or more members from a set. Deletes the set if the last member was removed. | O(N) where N is the number of members to be rem... | 1.0.0 | | [SSCAN](https://redis.io/commands/sscan/) | Iterates over members of a set. | O(1) for every call. O(N) for a complete iterat... | 2.8.0 | | [SUNION](https://redis.io/commands/sunion/) | Returns the union of multiple sets. | O(N) where N is the total number of elements in... | 1.0.0 | | [SUNIONCARD](https://redis.io/commands/sunioncard/) | Returns the number of members of the union of multiple sets. | O(N) where N is the total number of elements in... | 8.10.0 | | [SUNIONSTORE](https://redis.io/commands/sunionstore/) | Stores the union of multiple sets in a key. | O(N) where N is the total number of elements in... | 1.0.0 | A Redis set is an unordered collection of unique strings (members). You can use Redis sets to efficiently: * Track unique items (e.g., track all unique IP addresses accessing a given blog post). * Represent relations (e.g., the set of all users with a given role). * Perform common set operations such as intersection, unions, and differences. ## Examples * Store the sets of bikes racing in France and the USA. Note that if you add a member that already exists, it will be ignored. Foundational: Add members to a set using SADD when you need to store unique items (duplicates are silently ignored) **Difficulty:** Beginner **Commands:** SADD **Complexity:** - SADD: O(1) **Available in:** Redis CLI, C#, Go, Java (Asynchronous - Lettuce), Java (Reactive - Lettuce), Java (Synchronous - Jedis), JavaScript (Node.js), PHP, Python, Ruby, Rust (Asynchronous), Rust (Synchronous) ##### Redis CLI ``` > SADD bikes:racing:france bike:1 (integer) 1 > SADD bikes:racing:france bike:1 (integer) 0 > SADD bikes:racing:france bike:2 bike:3 (integer) 2 > SADD bikes:racing:usa bike:1 bike:4 (integer) 2 ``` ##### C# ```csharp long res1 = db.SetAdd("bikes:racing:france", ["bike:1"]); Console.WriteLine(res1); // >>> 1 long res2 = db.SetAdd("bikes:racing:france", ["bike:1"]); Console.WriteLine(res2); // >>> 0 long res3 = db.SetAdd("bikes:racing:france", ["bike:2", "bike:3"]); Console.WriteLine(res3); // >>> 2 long res4 = db.SetAdd("bikes:racing:usa", ["bike:1", "bike:4"]); Console.WriteLine(res4); // >>> 2 ``` ##### Go ```go res1, err := rdb.SAdd(ctx, "bikes:racing:france", "bike:1").Result() if err != nil { panic(err) } fmt.Println(res1) // >>> 1 res2, err := rdb.SAdd(ctx, "bikes:racing:france", "bike:1").Result() if err != nil { panic(err) } fmt.Println(res2) // >>> 0 res3, err := rdb.SAdd(ctx, "bikes:racing:france", "bike:2", "bike:3").Result() if err != nil { panic(err) } fmt.Println(res3) // >>> 2 res4, err := rdb.SAdd(ctx, "bikes:racing:usa", "bike:1", "bike:4").Result() if err != nil { panic(err) } fmt.Println(res4) // >>> 2 ``` ##### Java (Asynchronous - Lettuce) ```java CompletableFuture sAdd = asyncCommands.sadd("bikes:racing:france", "bike:1").thenCompose(res1 -> { System.out.println(res1); // >>> 1 return asyncCommands.sadd("bikes:racing:france", "bike:1"); }).thenCompose(res2 -> { System.out.println(res2); // >>> 0 return asyncCommands.sadd("bikes:racing:france", "bike:2", "bike:3"); }).thenCompose(res3 -> { System.out.println(res3); // >>> 2 return asyncCommands.sadd("bikes:racing:usa", "bike:1", "bike:4"); }).thenAccept(res4 -> { System.out.println(res4); // >>> 2 }).toCompletableFuture(); ``` ##### Java (Reactive - Lettuce) ```java Mono sAdd = reactiveCommands.sadd("bikes:racing:france", "bike:1").doOnNext(result -> { System.out.println(result); // >>> 1 }).flatMap(v -> reactiveCommands.sadd("bikes:racing:france", "bike:1")).doOnNext(result -> { System.out.println(result); // >>> 0 }).flatMap(v -> reactiveCommands.sadd("bikes:racing:france", "bike:2", "bike:3")).doOnNext(result -> { System.out.println(result); // >>> 2 }).flatMap(v -> reactiveCommands.sadd("bikes:racing:usa", "bike:1", "bike:4")).doOnNext(result -> { System.out.println(result); // >>> 2 }).then(); ``` ##### Java (Synchronous - Jedis) ```java long res1 = jedis.sadd("bikes:racing:france", "bike:1"); System.out.println(res1); // >>> 1 long res2 = jedis.sadd("bikes:racing:france", "bike:1"); System.out.println(res2); // >>> 0 long res3 = jedis.sadd("bikes:racing:france", "bike:2", "bike:3"); System.out.println(res3); // >>> 2 long res4 = jedis.sadd("bikes:racing:usa", "bike:1", "bike:4"); System.out.println(res4); // >>> 2 ``` ##### JavaScript (Node.js) ```javascript const res1 = await client.sAdd('bikes:racing:france', 'bike:1') console.log(res1) // >>> 1 const res2 = await client.sAdd('bikes:racing:france', 'bike:1') console.log(res2) // >>> 0 const res3 = await client.sAdd('bikes:racing:france', ['bike:2', 'bike:3']) console.log(res3) // >>> 2 const res4 = await client.sAdd('bikes:racing:usa', ['bike:1', 'bike:4']) console.log(res4) // >>> 2 ``` ##### PHP ```php $res1 = $r->sadd('bikes:racing:france', ['bike:1']); echo $res1 . PHP_EOL; // >>> 1 $res2 = $r->sadd('bikes:racing:france', ['bike:1']); echo $res2 . PHP_EOL; // >>> 0 $res3 = $r->sadd('bikes:racing:france', ['bike:2', 'bike:3']); echo $res3 . PHP_EOL; // >>> 2 $res4 = $r->sadd('bikes:racing:usa', ['bike:1', 'bike:4']); echo $res4 . PHP_EOL; // >>> 2 ``` ##### Python ```python res1 = r.sadd("bikes:racing:france", "bike:1") print(res1) # >>> 1 res2 = r.sadd("bikes:racing:france", "bike:1") print(res2) # >>> 0 res3 = r.sadd("bikes:racing:france", "bike:2", "bike:3") print(res3) # >>> 2 res4 = r.sadd("bikes:racing:usa", "bike:1", "bike:4") print(res4) # >>> 2 ``` ##### Ruby ```ruby res1 = r.sadd('bikes:racing:france', ['bike:1']) puts res1 # >>> 1 res2 = r.sadd('bikes:racing:france', ['bike:1']) puts res2 # >>> 0 res3 = r.sadd('bikes:racing:france', ['bike:2', 'bike:3']) puts res3 # >>> 2 res4 = r.sadd('bikes:racing:usa', ['bike:1', 'bike:4']) puts res4 # >>> 2 ``` ##### Rust (Asynchronous) ```rust if let Ok(res) = r.sadd("bikes:racing:france", "bike:1").await { let res: usize = res; println!("{res}"); // >>> 1 } if let Ok(res) = r.sadd("bikes:racing:france", "bike:1").await { let res: usize = res; println!("{res}"); // >>> 0 } if let Ok(res) = r.sadd("bikes:racing:france", &["bike:2", "bike:3"]).await { let res: usize = res; println!("{res}"); // >>> 2 } if let Ok(res) = r.sadd("bikes:racing:usa", &["bike:1", "bike:4"]).await { let res: usize = res; println!("{res}"); // >>> 2 } ``` ##### Rust (Synchronous) ```rust if let Ok(res) = r.sadd("bikes:racing:france", "bike:1") { let res: usize = res; println!("{res}"); // >>> 1 } if let Ok(res) = r.sadd("bikes:racing:france", "bike:1") { let res: usize = res; println!("{res}"); // >>> 0 } if let Ok(res) = r.sadd("bikes:racing:france", &["bike:2", "bike:3"]) { let res: usize = res; println!("{res}"); // >>> 2 } if let Ok(res) = r.sadd("bikes:racing:usa", &["bike:1", "bike:4"]) { let res: usize = res; println!("{res}"); // >>> 2 } ``` * Check whether bike:1 or bike:2 are racing in the US. Foundational: Test set membership using SISMEMBER when you need O(1) lookups (much faster than checking a list) **Difficulty:** Beginner **Builds upon:** sadd **Commands:** SISMEMBER **Complexity:** - SISMEMBER: O(1) **Available in:** Redis CLI, C#, Go, Java (Asynchronous - Lettuce), Java (Reactive - Lettuce), Java (Synchronous - Jedis), JavaScript (Node.js), PHP, Python, Ruby, Rust (Asynchronous), Rust (Synchronous) ##### Redis CLI ``` > SISMEMBER bikes:racing:usa bike:1 (integer) 1 > SISMEMBER bikes:racing:usa bike:2 (integer) 0 ``` ##### C# ```csharp bool res5 = db.SetContains("bikes:racing:france", "bike:1"); Console.WriteLine(res5); // >>> True bool res6 = db.SetContains("bikes:racing:usa", "bike:2"); Console.WriteLine(res6); // >>> False ``` ##### Go ```go res5, err := rdb.SIsMember(ctx, "bikes:racing:usa", "bike:1").Result() if err != nil { panic(err) } fmt.Println(res5) // >>> true res6, err := rdb.SIsMember(ctx, "bikes:racing:usa", "bike:2").Result() if err != nil { panic(err) } fmt.Println(res6) // >>> false ``` ##### Java (Asynchronous - Lettuce) ```java CompletableFuture sIsMember = asyncCommands.sismember("bikes:racing:usa", "bike:1").thenCompose(res5 -> { System.out.println(res5); // >>> true return asyncCommands.sismember("bikes:racing:usa", "bike:2"); }).thenAccept(res6 -> { System.out.println(res6); // >>> false }).toCompletableFuture(); ``` ##### Java (Reactive - Lettuce) ```java Mono sIsMember1 = reactiveCommands.sismember("bikes:racing:usa", "bike:1").doOnNext(result -> { System.out.println(result); // >>> true }); Mono sIsMember2 = reactiveCommands.sismember("bikes:racing:usa", "bike:2").doOnNext(result -> { System.out.println(result); // >>> false }); ``` ##### Java (Synchronous - Jedis) ```java jedis.sadd("bikes:racing:france", "bike:1", "bike:2", "bike:3"); jedis.sadd("bikes:racing:usa", "bike:1", "bike:4"); boolean res5 = jedis.sismember("bikes:racing:usa", "bike:1"); System.out.println(res5); // >>> true boolean res6 = jedis.sismember("bikes:racing:usa", "bike:2"); System.out.println(res6); // >>> false ``` ##### JavaScript (Node.js) ```javascript await client.del('bikes:racing:france') await client.del('bikes:racing:usa') await client.sAdd('bikes:racing:france', ['bike:1', 'bike:2', 'bike:3']) await client.sAdd('bikes:racing:usa', ['bike:1', 'bike:4']) const res5 = await client.sIsMember('bikes:racing:usa', 'bike:1') console.log(res5) // >>> 1 const res6 = await client.sIsMember('bikes:racing:usa', 'bike:2') console.log(res6) // >>> 0 ``` ##### PHP ```php $res5 = $r->sismember('bikes:racing:usa', 'bike:1'); echo $res5 . PHP_EOL; // >>> 1 $res6 = $r->sismember('bikes:racing:usa', 'bike:2'); echo $res6 . PHP_EOL; // >>> 0 ``` ##### Python ```python r.sadd("bikes:racing:france", "bike:1", "bike:2", "bike:3") r.sadd("bikes:racing:usa", "bike:1", "bike:4") res5 = r.sismember("bikes:racing:usa", "bike:1") print(res5) # >>> 1 res6 = r.sismember("bikes:racing:usa", "bike:2") print(res6) # >>> 0 ``` ##### Ruby ```ruby r.del('bikes:racing:france', 'bikes:racing:usa') r.sadd('bikes:racing:france', ['bike:1', 'bike:2', 'bike:3']) r.sadd('bikes:racing:usa', ['bike:1', 'bike:4']) res5 = r.sismember('bikes:racing:usa', 'bike:1') puts res5 # >>> true res6 = r.sismember('bikes:racing:usa', 'bike:2') puts res6 # >>> false ``` ##### Rust (Asynchronous) ```rust if let Ok(res) = r.sismember("bikes:racing:usa", "bike:1").await { let res: bool = res; println!("{}", i32::from(res)); // >>> 1 } if let Ok(res) = r.sismember("bikes:racing:usa", "bike:2").await { let res: bool = res; println!("{}", i32::from(res)); // >>> 0 } ``` ##### Rust (Synchronous) ```rust if let Ok(res) = r.sismember("bikes:racing:usa", "bike:1") { let res: bool = res; println!("{}", i32::from(res)); // >>> 1 } if let Ok(res) = r.sismember("bikes:racing:usa", "bike:2") { let res: bool = res; println!("{}", i32::from(res)); // >>> 0 } ``` * Which bikes are competing in both races? Set intersection: Find common members across multiple sets using SINTER when you need to identify shared items (e.g., users in multiple groups) **Difficulty:** Intermediate **Builds upon:** sadd **Commands:** SINTER **Complexity:** - SINTER: O(N*M) **Available in:** Redis CLI, C#, Go, Java (Asynchronous - Lettuce), Java (Reactive - Lettuce), Java (Synchronous - Jedis), JavaScript (Node.js), PHP, Python, Ruby, Rust (Asynchronous), Rust (Synchronous) ##### Redis CLI ``` > SINTER bikes:racing:france bikes:racing:usa 1) "bike:1" ``` ##### C# ```csharp long res7 = db.SetAdd("{bikes:racing}:france", ["bike:1", "bike:2", "bike:3"]); long res8 = db.SetAdd("{bikes:racing}:usa", ["bike:1", "bike:4"]); RedisValue[] res9 = db.SetCombine(SetOperation.Intersect, ["{bikes:racing}:france", "{bikes:racing}:usa"]); Console.WriteLine(string.Join(", ", res9)); // >>> bike:1 ``` ##### Go ```go res7, err := rdb.SInter(ctx, "bikes:racing:france", "bikes:racing:usa").Result() if err != nil { panic(err) } fmt.Println(res7) // >>> [bike:1] ``` ##### Java (Asynchronous - Lettuce) ```java CompletableFuture sInter = asyncCommands.sinter("bikes:racing:france", "bikes:racing:usa") .thenAccept(res7 -> { System.out.println(res7); // >>> [bike:1] }).toCompletableFuture(); ``` ##### Java (Reactive - Lettuce) ```java Mono> sInter = reactiveCommands.sinter("bikes:racing:france", "bikes:racing:usa").collectList() .doOnNext(result -> { System.out.println(result); // >>> [bike:1] }); ``` ##### Java (Synchronous - Jedis) ```java jedis.sadd("bikes:racing:france", "bike:1", "bike:2", "bike:3"); jedis.sadd("bikes:racing:usa", "bike:1", "bike:4"); Set res7 = jedis.sinter("bikes:racing:france", "bikes:racing:usa"); System.out.println(res7); // >>> [bike:1] ``` ##### JavaScript (Node.js) ```javascript await client.del('bikes:racing:france') await client.del('bikes:racing:usa') await client.sAdd('bikes:racing:france', ['bike:1', 'bike:2', 'bike:3']) await client.sAdd('bikes:racing:usa', ['bike:1', 'bike:4']) const res7 = await client.sInter(['bikes:racing:france', 'bikes:racing:usa']) console.log(res7) // >>> ['bike:1'] ``` ##### PHP ```php $res7 = $r->sinter(['bikes:racing:france', 'bikes:racing:usa']); echo json_encode($res7) . PHP_EOL; // >>> ["bike:1"] ``` ##### Python ```python r.sadd("bikes:racing:france", "bike:1", "bike:2", "bike:3") r.sadd("bikes:racing:usa", "bike:1", "bike:4") res7 = r.sinter("bikes:racing:france", "bikes:racing:usa") print(res7) # >>> {'bike:1'} ``` ##### Ruby ```ruby r.del('bikes:racing:france', 'bikes:racing:usa') r.sadd('bikes:racing:france', ['bike:1', 'bike:2', 'bike:3']) r.sadd('bikes:racing:usa', ['bike:1', 'bike:4']) res7 = r.sinter('bikes:racing:france', 'bikes:racing:usa') puts res7.inspect # >>> ["bike:1"] ``` ##### Rust (Asynchronous) ```rust if let Ok(res) = r.sinter(&["bikes:racing:france", "bikes:racing:usa"]).await { let res: HashSet = res; let res = sorted_set(res); println!("{res:?}"); // >>> ["bike:1"] } ``` ##### Rust (Synchronous) ```rust if let Ok(res) = r.sinter(&["bikes:racing:france", "bikes:racing:usa"]) { let res: HashSet = res; let res = sorted_set(res); println!("{res:?}"); // >>> ["bike:1"] } ``` * How many bikes are racing in France? Foundational: Get the cardinality of a set using SCARD when you need to count unique items efficiently **Difficulty:** Beginner **Builds upon:** sadd **Commands:** SCARD **Complexity:** - SCARD: O(1) **Available in:** Redis CLI, C#, Go, Java (Asynchronous - Lettuce), Java (Reactive - Lettuce), Java (Synchronous - Jedis), JavaScript (Node.js), PHP, Python, Ruby, Rust (Asynchronous), Rust (Synchronous) ##### Redis CLI ``` > SCARD bikes:racing:france (integer) 3 ``` ##### C# ```csharp long res10 = db.SetAdd("bikes:racing:france", ["bike:1", "bike:2", "bike:3"]); long res11 = db.SetLength("bikes:racing:france"); Console.WriteLine(res11); // >>> 3 ``` ##### Go ```go res8, err := rdb.SCard(ctx, "bikes:racing:france").Result() if err != nil { panic(err) } fmt.Println(res8) // >>> 3 ``` ##### Java (Asynchronous - Lettuce) ```java CompletableFuture sCard = asyncCommands.scard("bikes:racing:france").thenAccept(res8 -> { System.out.println(res8); // >>> 3 }).toCompletableFuture(); ``` ##### Java (Reactive - Lettuce) ```java Mono sCard = reactiveCommands.scard("bikes:racing:france").doOnNext(result -> { System.out.println(result); // >>> 3 }); ``` ##### Java (Synchronous - Jedis) ```java jedis.sadd("bikes:racing:france", "bike:1", "bike:2", "bike:3"); long res8 = jedis.scard("bikes:racing:france"); System.out.println(res8); // >>> 3 ``` ##### JavaScript (Node.js) ```javascript await client.del('bikes:racing:france') await client.sAdd('bikes:racing:france', ['bike:1', 'bike:2', 'bike:3']) const res8 = await client.sCard('bikes:racing:france') console.log(res8) // >>> 3 ``` ##### PHP ```php $res8 = $r->scard('bikes:racing:france'); echo $res8 . PHP_EOL; // >>> 3 ``` ##### Python ```python r.sadd("bikes:racing:france", "bike:1", "bike:2", "bike:3") res8 = r.scard("bikes:racing:france") print(res8) # >>> 3 ``` ##### Ruby ```ruby r.del('bikes:racing:france') r.sadd('bikes:racing:france', ['bike:1', 'bike:2', 'bike:3']) res8 = r.scard('bikes:racing:france') puts res8 # >>> 3 ``` ##### Rust (Asynchronous) ```rust if let Ok(res) = r.scard("bikes:racing:france").await { let res: usize = res; println!("{res}"); // >>> 3 } ``` ##### Rust (Synchronous) ```rust if let Ok(res) = r.scard("bikes:racing:france") { let res: usize = res; println!("{res}"); // >>> 3 } ``` ## Tutorial The [`SADD`](https://redis.io/docs/latest/commands/sadd) command adds new elements to a set. It's also possible to do a number of other operations against sets like testing if a given element already exists, performing the intersection, union or difference between multiple sets, and so forth. Foundational: Retrieve all members from a set using SMEMBERS when you need the complete set (note: order is not guaranteed) **Difficulty:** Beginner **Builds upon:** sadd **Commands:** DEL, SADD, SMEMBERS **Complexity:** - DEL: O(N) - SADD: O(1) - SMEMBERS: O(N) **Available in:** Redis CLI, C#, Go, Java (Asynchronous - Lettuce), Java (Reactive - Lettuce), Java (Synchronous - Jedis), JavaScript (Node.js), PHP, Python, Ruby, Rust (Asynchronous), Rust (Synchronous) ##### Redis CLI ``` > DEL bikes:racing:france (integer) 1 > SADD bikes:racing:france bike:1 bike:2 bike:3 (integer) 3 > SMEMBERS bikes:racing:france 1) "bike:3" 2) "bike:1" 3) "bike:2" ``` ##### C# ```csharp db.KeyDelete("bikes:racing:france"); long res12 = db.SetAdd("bikes:racing:france", ["bike:1", "bike:2", "bike:3"]); RedisValue[] res13 = db.SetMembers("bikes:racing:france"); Console.WriteLine(string.Join(", ", res13)); // >>> bike:3, bike:2, bike:1 ``` ##### Go ```go rdb.Del(ctx, "bikes:racing:france") res9, err := rdb.SAdd(ctx, "bikes:racing:france", "bike:1", "bike:2", "bike:3").Result() if err != nil { panic(err) } fmt.Println(res9) // >>> 3 res10, err := rdb.SMembers(ctx, "bikes:racing:france").Result() if err != nil { panic(err) } // Sort the strings in the slice to make sure the output is lexicographical sort.Strings(res10) fmt.Println(res10) // >>> [bike:1 bike:2 bike:3] ``` ##### Java (Asynchronous - Lettuce) ```java CompletableFuture sAddSMembers = asyncCommands.sadd("bikes:racing:france", "bike:1", "bike:2", "bike:3") .thenCompose(res9 -> { System.out.println(res9); // >>> 3 return asyncCommands.smembers("bikes:racing:france"); }).thenAccept(res10 -> { System.out.println(res10); // >>> [bike:1, bike:2, bike:3] }).toCompletableFuture(); ``` ##### Java (Reactive - Lettuce) ```java Mono sAddSMembers = reactiveCommands.sadd("bikes:racing:france", "bike:1", "bike:2", "bike:3") .doOnNext(result -> { System.out.println(result); // >>> 3 }).flatMap(v -> reactiveCommands.smembers("bikes:racing:france").collectList()).doOnNext(result -> { System.out.println(result); // >>> [bike:1, bike:2, bike:3] }).then(); ``` ##### Java (Synchronous - Jedis) ```java jedis.del("bikes:racing:france"); long res9 = jedis.sadd("bikes:racing:france", "bike:1", "bike:2", "bike:3"); System.out.println(res9); // >>> 3 Set res10 = jedis.smembers("bikes:racing:france"); System.out.println(res10); // >>> [bike:1, bike:2, bike:3] ``` ##### JavaScript (Node.js) ```javascript await client.del('bikes:racing:france') const res9 = await client.sAdd('bikes:racing:france', ['bike:1', 'bike:2', 'bike:3']) console.log(res9) // >>> 3 const res10 = await client.sMembers('bikes:racing:france') console.log(res10) // >>> ['bike:1', 'bike:2', 'bike:3'] ``` ##### PHP ```php $r->del('bikes:racing:france'); $res9 = $r->sadd('bikes:racing:france', ['bike:1', 'bike:2', 'bike:3']); echo $res9 . PHP_EOL; // >>> 3 $res10 = $r->smembers('bikes:racing:france'); sort($res10); echo json_encode($res10) . PHP_EOL; // >>> ["bike:1","bike:2","bike:3"] ``` ##### Python ```python r.delete("bikes:racing:france") res9 = r.sadd("bikes:racing:france", "bike:1", "bike:2", "bike:3") print(res9) # >>> 3 res10 = r.smembers("bikes:racing:france") print(res10) # >>> {'bike:1', 'bike:2', 'bike:3'} ``` ##### Ruby ```ruby r.del('bikes:racing:france') res9 = r.sadd('bikes:racing:france', ['bike:1', 'bike:2', 'bike:3']) puts res9 # >>> 3 res10 = r.smembers('bikes:racing:france') puts res10.sort.inspect # >>> ["bike:1", "bike:2", "bike:3"] ``` ##### Rust (Asynchronous) ```rust let _: usize = r.del("bikes:racing:france").await.unwrap_or(0); if let Ok(res) = r.sadd("bikes:racing:france", &["bike:1", "bike:2", "bike:3"]).await { let res: usize = res; println!("{res}"); // >>> 3 } if let Ok(res) = r.smembers("bikes:racing:france").await { let res: HashSet = res; let res = sorted_set(res); println!("{res:?}"); // >>> ["bike:1", "bike:2", "bike:3"] } ``` ##### Rust (Synchronous) ```rust let _: usize = r.del("bikes:racing:france").unwrap_or(0); if let Ok(res) = r.sadd("bikes:racing:france", &["bike:1", "bike:2", "bike:3"]) { let res: usize = res; println!("{res}"); // >>> 3 } if let Ok(res) = r.smembers("bikes:racing:france") { let res: HashSet = res; let res = sorted_set(res); println!("{res:?}"); // >>> ["bike:1", "bike:2", "bike:3"] } ``` Here I've added three elements to my set and told Redis to return all the elements. There is no order guarantee with a set. Redis is free to return the elements in any order at every call. Redis has commands to test for set membership. These commands can be used on single as well as multiple items: Batch membership checks: Test multiple items at once using SMISMEMBER when you need to reduce round trips to the server **Difficulty:** Intermediate **Builds upon:** sismember **Commands:** DEL, SADD, SISMEMBER, SMISMEMBER **Complexity:** - DEL: O(N) - SADD: O(1) - SISMEMBER: O(1) - SMISMEMBER: O(N) **Available in:** Redis CLI, C#, Go, Java (Asynchronous - Lettuce), Java (Reactive - Lettuce), Java (Synchronous - Jedis), JavaScript (Node.js), PHP, Python, Ruby, Rust (Asynchronous), Rust (Synchronous) ##### Redis CLI ``` # Recreate the France racing set so this example runs on its own. > DEL bikes:racing:france (integer) 1 > SADD bikes:racing:france bike:1 bike:2 bike:3 (integer) 3 > SISMEMBER bikes:racing:france bike:1 (integer) 1 > SMISMEMBER bikes:racing:france bike:2 bike:3 bike:4 1) (integer) 1 2) (integer) 1 3) (integer) 0 ``` ##### C# ```csharp // Recreate the set so this example runs on its own. db.KeyDelete("bikes:racing:france"); db.SetAdd("bikes:racing:france", ["bike:1", "bike:2", "bike:3"]); bool res14 = db.SetContains("bikes:racing:france", "bike:1"); Console.WriteLine(res14); // >>> true bool[] res15 = db.SetContains("bikes:racing:france", ["bike:2", "bike:3", "bike:4"]); Console.WriteLine(string.Join(", ", res15)); // >>> True, True, False ``` ##### Go ```go res11, err := rdb.SIsMember(ctx, "bikes:racing:france", "bike:1").Result() if err != nil { panic(err) } fmt.Println(res11) // >>> true res12, err := rdb.SMIsMember(ctx, "bikes:racing:france", "bike:2", "bike:3", "bike:4").Result() if err != nil { panic(err) } fmt.Println(res12) // >>> [true true false] ``` ##### Java (Asynchronous - Lettuce) ```java // Recreate the set so this example runs on its own. The chain is // ordered, so the DEL + SADD complete before the reads below. CompletableFuture sMIsMember = asyncCommands.del("bikes:racing:france") .thenCompose(d -> asyncCommands.sadd("bikes:racing:france", "bike:1", "bike:2", "bike:3")) .thenCompose(a -> asyncCommands.sismember("bikes:racing:france", "bike:1")).thenCompose(res11 -> { System.out.println(res11); // >>> true return asyncCommands.smismember("bikes:racing:france", "bike:2", "bike:3", "bike:4"); }).thenAccept(res12 -> { System.out.println(res12); // >>> [true, true, false] }).toCompletableFuture(); ``` ##### Java (Reactive - Lettuce) ```java // Recreate the set so this example runs on its own. Block it // sequentially: a DEL inside the shared Mono.when() below would // race the sibling reads on the same key. reactiveCommands.del("bikes:racing:france") .then(reactiveCommands.sadd("bikes:racing:france", "bike:1", "bike:2", "bike:3")) .block(); Mono sIsMember3 = reactiveCommands.sismember("bikes:racing:france", "bike:1").doOnNext(result -> { System.out.println(result); // >>> true }); Mono> sMIsMember = reactiveCommands.smismember("bikes:racing:france", "bike:2", "bike:3", "bike:4") .collectList().doOnNext(result -> { System.out.println(result); // >>> [true, true, false] }); ``` ##### Java (Synchronous - Jedis) ```java // Recreate the set so this example runs on its own. jedis.del("bikes:racing:france"); jedis.sadd("bikes:racing:france", "bike:1", "bike:2", "bike:3"); boolean res11 = jedis.sismember("bikes:racing:france", "bike:1"); System.out.println(res11); // >>> true List res12 = jedis.smismember("bikes:racing:france", "bike:2", "bike:3", "bike:4"); System.out.println(res12); // >>> [true,true,false] ``` ##### JavaScript (Node.js) ```javascript // Recreate the set so this example runs on its own. await client.del('bikes:racing:france') await client.sAdd('bikes:racing:france', ['bike:1', 'bike:2', 'bike:3']) const res11 = await client.sIsMember('bikes:racing:france', 'bike:1') console.log(res11) // >>> 1 const res12 = await client.smIsMember('bikes:racing:france', ['bike:2', 'bike:3', 'bike:4']) console.log(res12) // >>> [1, 1, 0] ``` ##### PHP ```php // Recreate the set so this example runs on its own. $r->del('bikes:racing:france'); $r->sadd('bikes:racing:france', 'bike:1', 'bike:2', 'bike:3'); $res11 = $r->sismember('bikes:racing:france', 'bike:1'); echo $res11 . PHP_EOL; // >>> 1 $res12 = $r->smismember('bikes:racing:france', 'bike:2', 'bike:3', 'bike:4'); echo json_encode($res12) . PHP_EOL; // >>> [1,1,0] ``` ##### Python ```python # Recreate the set so this example runs on its own. r.delete("bikes:racing:france") r.sadd("bikes:racing:france", "bike:1", "bike:2", "bike:3") res11 = r.sismember("bikes:racing:france", "bike:1") print(res11) # >>> 1 res12 = r.smismember("bikes:racing:france", "bike:2", "bike:3", "bike:4") print(res12) # >>> [1, 1, 0] ``` ##### Ruby ```ruby # Recreate the set so this example runs on its own. r.del('bikes:racing:france') r.sadd('bikes:racing:france', ['bike:1', 'bike:2', 'bike:3']) res11 = r.sismember('bikes:racing:france', 'bike:1') puts res11 # >>> true res12 = r.smismember('bikes:racing:france', 'bike:2', 'bike:3', 'bike:4') puts res12.inspect # >>> [true, true, false] ``` ##### Rust (Asynchronous) ```rust // Recreate the set so this example runs on its own. let _: usize = r.del("bikes:racing:france").await.unwrap_or(0); let _: usize = r .sadd("bikes:racing:france", &["bike:1", "bike:2", "bike:3"]) .await .unwrap_or(0); if let Ok(res) = r.sismember("bikes:racing:france", "bike:1").await { let res: bool = res; println!("{}", i32::from(res)); // >>> 1 } if let Ok(res) = r .smismember("bikes:racing:france", &["bike:2", "bike:3", "bike:4"]) .await { let res: Vec = res; let res: Vec = res.into_iter().map(i32::from).collect(); println!("{res:?}"); // >>> [1, 1, 0] } ``` ##### Rust (Synchronous) ```rust // Recreate the set so this example runs on its own. let _: usize = r.del("bikes:racing:france").unwrap_or(0); let _: usize = r .sadd("bikes:racing:france", &["bike:1", "bike:2", "bike:3"]) .unwrap_or(0); if let Ok(res) = r.sismember("bikes:racing:france", "bike:1") { let res: bool = res; println!("{}", i32::from(res)); // >>> 1 } if let Ok(res) = r.smismember("bikes:racing:france", &["bike:2", "bike:3", "bike:4"]) { let res: Vec = res; let res: Vec = res.into_iter().map(i32::from).collect(); println!("{res:?}"); // >>> [1, 1, 0] } ``` We can also find the difference between two sets. For instance, we may want to know which bikes are racing in France but not in the USA: Set difference: Find members in one set but not in others using SDIFF when you need to exclude items (warning: argument order matters) **Difficulty:** Intermediate **Builds upon:** sadd **Commands:** DEL, SADD, SDIFF **Complexity:** - DEL: O(N) - SADD: O(1) - SDIFF: O(N) **Available in:** Redis CLI, C#, Go, Java (Asynchronous - Lettuce), Java (Reactive - Lettuce), Java (Synchronous - Jedis), JavaScript (Node.js), PHP, Python, Ruby, Rust (Asynchronous), Rust (Synchronous) ##### Redis CLI ``` > DEL bikes:racing:usa (integer) 1 > SADD bikes:racing:usa bike:1 bike:4 (integer) 2 > SDIFF bikes:racing:france bikes:racing:usa 1) "bike:3" 2) "bike:2" ``` ##### C# ```csharp long res16 = db.SetAdd("{bikes:racing}:france", ["bike:1", "bike:2", "bike:3"]); long res17 = db.SetAdd("{bikes:racing}:usa", ["bike:1", "bike:4"]); RedisValue[] res18 = db.SetCombine(SetOperation.Difference, ["{bikes:racing}:france", "{bikes:racing}:usa"]); Console.WriteLine(string.Join(", ", res18)); // >>> bike:2, bike:3 ``` ##### Go ```go _, err := rdb.SAdd(ctx, "bikes:racing:france", "bike:1", "bike:2", "bike:3").Result() if err != nil { panic(err) } _, err = rdb.SAdd(ctx, "bikes:racing:usa", "bike:1", "bike:4").Result() res13, err := rdb.SDiff(ctx, "bikes:racing:france", "bikes:racing:usa").Result() if err != nil { panic(err) } // Sort the strings in the slice to make sure the output is lexicographical sort.Strings(res13) fmt.Println(res13) // >>> [bike:2 bike:3] ``` ##### Java (Asynchronous - Lettuce) ```java CompletableFuture sDiff = asyncCommands.sdiff("bikes:racing:france", "bikes:racing:usa") .thenAccept(res13 -> { System.out.println(res13); // >>> [bike:2, bike:3] }).toCompletableFuture(); ``` ##### Java (Reactive - Lettuce) ```java Mono> sDiff = reactiveCommands.sdiff("bikes:racing:france", "bikes:racing:usa").collectList() .doOnNext(result -> { System.out.println(result); // >>> [bike:2, bike:3] }); ``` ##### Java (Synchronous - Jedis) ```java jedis.sadd("bikes:racing:france", "bike:1", "bike:2", "bike:3"); jedis.sadd("bikes:racing:usa", "bike:1", "bike:4"); Set res13 = jedis.sdiff("bikes:racing:france", "bikes:racing:usa"); System.out.println(res13); // >>> [bike:2, bike:3] ``` ##### JavaScript (Node.js) ```javascript await client.del('bikes:racing:france') await client.del('bikes:racing:usa') await client.sAdd('bikes:racing:france', ['bike:1', 'bike:2', 'bike:3']) await client.sAdd('bikes:racing:usa', ['bike:1', 'bike:4']) const res13 = await client.sDiff(['bikes:racing:france', 'bikes:racing:usa']) console.log(res13) // >>> [ 'bike:2', 'bike:3' ] ``` ##### PHP ```php $r->sadd('bikes:racing:france', ['bike:1', 'bike:2', 'bike:3']); $r->sadd('bikes:racing:usa', ['bike:1', 'bike:4']); $res13 = $r->sdiff(['bikes:racing:france', 'bikes:racing:usa']); sort($res13); echo json_encode($res13) . PHP_EOL; // >>> ["bike:2","bike:3"] ``` ##### Python ```python r.sadd("bikes:racing:france", "bike:1", "bike:2", "bike:3") r.sadd("bikes:racing:usa", "bike:1", "bike:4") res13 = r.sdiff("bikes:racing:france", "bikes:racing:usa") print(res13) # >>> {'bike:2', 'bike:3'} ``` ##### Ruby ```ruby r.sadd('bikes:racing:france', ['bike:1', 'bike:2', 'bike:3']) r.sadd('bikes:racing:usa', ['bike:1', 'bike:4']) res13 = r.sdiff('bikes:racing:france', 'bikes:racing:usa') puts res13.sort.inspect # >>> ["bike:2", "bike:3"] ``` ##### Rust (Asynchronous) ```rust let _: usize = r.del("bikes:racing:france").await.unwrap_or(0); let _: usize = r.del("bikes:racing:usa").await.unwrap_or(0); let _: usize = r .sadd("bikes:racing:france", &["bike:1", "bike:2", "bike:3"]) .await .unwrap_or(0); let _: usize = r .sadd("bikes:racing:usa", &["bike:1", "bike:4"]) .await .unwrap_or(0); if let Ok(res) = r.sdiff(&["bikes:racing:france", "bikes:racing:usa"]).await { let res: HashSet = res; let res = sorted_set(res); println!("{res:?}"); // >>> ["bike:2", "bike:3"] } ``` ##### Rust (Synchronous) ```rust let _: usize = r.del("bikes:racing:france").unwrap_or(0); let _: usize = r.del("bikes:racing:usa").unwrap_or(0); let _: usize = r.sadd("bikes:racing:france", &["bike:1", "bike:2", "bike:3"]).unwrap_or(0); let _: usize = r.sadd("bikes:racing:usa", &["bike:1", "bike:4"]).unwrap_or(0); if let Ok(res) = r.sdiff(&["bikes:racing:france", "bikes:racing:usa"]) { let res: HashSet = res; let res = sorted_set(res); println!("{res:?}"); // >>> ["bike:2", "bike:3"] } ``` There are other non trivial operations that are still easy to implement using the right Redis commands. For instance we may want a list of all the bikes racing in France, the USA, and some other races. We can do this using the [`SINTER`](https://redis.io/docs/latest/commands/sinter) command, which performs the intersection between different sets. In addition to intersection you can also perform unions, difference, and more. For example if we add a third race we can see some of these commands in action: Advanced pattern: Combine SINTER, SUNION, and SDIFF to analyze complex relationships when you need to precompute set algebra across multiple datasets **Difficulty:** Advanced **Builds upon:** sinter, sdiff **Commands:** DEL, SADD, SINTER, SUNION, SDIFF **Complexity:** - DEL: O(N) - SADD: O(1) - SINTER: O(N*M) - SUNION: O(N) - SDIFF: O(N) **Available in:** Redis CLI, C#, Go, Java (Asynchronous - Lettuce), Java (Reactive - Lettuce), Java (Synchronous - Jedis), JavaScript (Node.js), PHP, Python, Ruby, Rust (Asynchronous), Rust (Synchronous) ##### Redis CLI ``` > DEL bikes:racing:france bikes:racing:usa bikes:racing:italy (integer) 2 > SADD bikes:racing:france bike:1 bike:2 bike:3 (integer) 3 > SADD bikes:racing:usa bike:1 bike:4 (integer) 2 > SADD bikes:racing:italy bike:1 bike:2 bike:3 bike:4 (integer) 4 > SINTER bikes:racing:france bikes:racing:usa bikes:racing:italy 1) "bike:1" > SUNION bikes:racing:france bikes:racing:usa bikes:racing:italy 1) "bike:2" 2) "bike:1" 3) "bike:4" 4) "bike:3" > SDIFF bikes:racing:france bikes:racing:usa bikes:racing:italy (empty array) > SDIFF bikes:racing:france bikes:racing:usa 1) "bike:3" 2) "bike:2" > SDIFF bikes:racing:usa bikes:racing:france 1) "bike:4" ``` ##### C# ```csharp db.KeyDelete("{bikes:racing}:france"); db.KeyDelete("{bikes:racing}:usa"); db.KeyDelete("{bikes:racing}:italy"); long res19 = db.SetAdd("{bikes:racing}:france", ["bike:1", "bike:2", "bike:3"]); long res20 = db.SetAdd("{bikes:racing}:usa", ["bike:1", "bike:4"]); long res21 = db.SetAdd("{bikes:racing}:italy", ["bike:1", "bike:2", "bike:3", "bike:4"]); RedisValue[] res22 = db.SetCombine(SetOperation.Intersect, ["{bikes:racing}:france", "{bikes:racing}:usa", "{bikes:racing}:italy" ]); Console.WriteLine(string.Join(", ", res22)); // >>> bike:1 RedisValue[] res23 = db.SetCombine(SetOperation.Union, ["{bikes:racing}:france", "{bikes:racing}:usa", "{bikes:racing}:italy" ]); Console.WriteLine(string.Join(", ", res23)); // >>> bike:1, bike:2, bike:3, bike:4 RedisValue[] res24 = db.SetCombine(SetOperation.Difference, ["{bikes:racing}:france", "{bikes:racing}:usa", "{bikes:racing}:italy" ]); Console.WriteLine(string.Join(", ", res24)); // >>> RedisValue[] res25 = db.SetCombine(SetOperation.Difference, ["{bikes:racing}:usa", "{bikes:racing}:france"]); Console.WriteLine(string.Join(", ", res25)); // >>> bike:4 RedisValue[] res26 = db.SetCombine(SetOperation.Difference, ["{bikes:racing}:france", "{bikes:racing}:usa"]); Console.WriteLine(string.Join(", ", res26)); // >>> bike:2, bike:3 ``` ##### Go ```go rdb.Del(ctx, "bikes:racing:france") rdb.Del(ctx, "bikes:racing:usa") rdb.Del(ctx, "bikes:racing:italy") _, err := rdb.SAdd(ctx, "bikes:racing:france", "bike:1", "bike:2", "bike:3").Result() if err != nil { panic(err) } _, err = rdb.SAdd(ctx, "bikes:racing:usa", "bike:1", "bike:4").Result() if err != nil { panic(err) } _, err = rdb.SAdd(ctx, "bikes:racing:italy", "bike:1", "bike:2", "bike:3", "bike:4").Result() if err != nil { panic(err) } res14, err := rdb.SInter(ctx, "bikes:racing:france", "bikes:racing:usa", "bikes:racing:italy").Result() if err != nil { panic(err) } fmt.Println(res14) // >>> [bike:1] res15, err := rdb.SUnion(ctx, "bikes:racing:france", "bikes:racing:usa", "bikes:racing:italy").Result() if err != nil { panic(err) } // Sort the strings in the slice to make sure the output is lexicographical sort.Strings(res15) fmt.Println(res15) // >>> [bike:1 bike:2 bike:3 bike:4] res16, err := rdb.SDiff(ctx, "bikes:racing:france", "bikes:racing:usa", "bikes:racing:italy").Result() if err != nil { panic(err) } fmt.Println(res16) // >>> [] res17, err := rdb.SDiff(ctx, "bikes:racing:usa", "bikes:racing:france").Result() if err != nil { panic(err) } fmt.Println(res17) // >>> [bike:4] res18, err := rdb.SDiff(ctx, "bikes:racing:france", "bikes:racing:usa").Result() if err != nil { panic(err) } // Sort the strings in the slice to make sure the output is lexicographical sort.Strings(res18) fmt.Println(res18) // >>> [bike:2 bike:3] ``` ##### Java (Asynchronous - Lettuce) ```java CompletableFuture multisets = asyncCommands.sadd("bikes:racing:france", "bike:1", "bike:2", "bike:3") .thenCompose(res14 -> { System.out.println(res14); // >>> 0 return asyncCommands.sadd("bikes:racing:usa", "bike:1", "bike:4"); }).thenCompose(res15 -> { System.out.println(res15); // >>> 0 return asyncCommands.sadd("bikes:racing:italy", "bike:1", "bike:2", "bike:3", "bike:4"); }).thenCompose(res16 -> { System.out.println(res16); // >>> 4 return asyncCommands.sinter("bikes:racing:france", "bikes:racing:usa", "bikes:racing:italy"); }).thenCompose(res17 -> { System.out.println(res17); // >>> [bike:1] return asyncCommands.sunion("bikes:racing:france", "bikes:racing:usa", "bikes:racing:italy"); }).thenCompose(res18 -> { System.out.println(res18); // >>> [bike:1, bike:2, bike:3, bike:4] return asyncCommands.sdiff("bikes:racing:france", "bikes:racing:usa", "bikes:racing:italy"); }).thenCompose(res19 -> { System.out.println(res19); // >>> [] return asyncCommands.sdiff("bikes:racing:usa", "bikes:racing:france"); }).thenCompose(res20 -> { System.out.println(res20); // >>> [bike:4] return asyncCommands.sdiff("bikes:racing:france", "bikes:racing:usa"); }).thenAccept(res21 -> { System.out.println(res21); // >>> [bike:2, bike:3] }).toCompletableFuture(); ``` ##### Java (Reactive - Lettuce) ```java Mono add3sets = reactiveCommands.sadd("bikes:racing:france", "bike:1", "bike:2", "bike:3") .doOnNext(result -> { System.out.println(result); // >>> 0 }).flatMap(v -> reactiveCommands.sadd("bikes:racing:usa", "bike:1", "bike:4")).doOnNext(result -> { System.out.println(result); // >>> 0 }).flatMap(v -> reactiveCommands.sadd("bikes:racing:italy", "bike:1", "bike:2", "bike:3", "bike:4")) .doOnNext(result -> { System.out.println(result); // >>> 4, }).then(); add3sets.block(); Mono> multisets1 = reactiveCommands .sinter("bikes:racing:france", "bikes:racing:usa", "bikes:racing:italy").collectList().doOnNext(result -> { System.out.println(result); // >>> [bike:1] }); Mono> multisets2 = reactiveCommands .sunion("bikes:racing:france", "bikes:racing:usa", "bikes:racing:italy").collectList().doOnNext(result -> { System.out.println(result); // >>> [bike:1, bike:2, bike:3, bike:4] }); Mono> multisets3 = reactiveCommands .sdiff("bikes:racing:france", "bikes:racing:usa", "bikes:racing:italy").collectList().doOnNext(result -> { System.out.println(result); // >>> [] }); Mono> multisets4 = reactiveCommands.sdiff("bikes:racing:usa", "bikes:racing:france").collectList() .doOnNext(result -> { System.out.println(result); // >>> [bike:4] }); Mono> multisets5 = reactiveCommands.sdiff("bikes:racing:france", "bikes:racing:usa").collectList() .doOnNext(result -> { System.out.println(result); // >>> [bike:2, bike:3] }); ``` ##### Java (Synchronous - Jedis) ```java jedis.del("bikes:racing:france"); jedis.del("bikes:racing:usa"); jedis.del("bikes:racing:italy"); jedis.sadd("bikes:racing:france", "bike:1", "bike:2", "bike:3"); jedis.sadd("bikes:racing:usa", "bike:1", "bike:4"); jedis.sadd("bikes:racing:italy", "bike:1", "bike:2", "bike:3", "bike:4"); Set res14 = jedis.sinter("bikes:racing:france", "bikes:racing:usa", "bikes:racing:italy"); System.out.println(res14); // >>> [bike:1] Set res15 = jedis.sunion("bikes:racing:france", "bikes:racing:usa", "bikes:racing:italy"); System.out.println(res15); // >>> [bike:1, bike:2, bike:3, bike:4] Set res16 = jedis.sdiff("bikes:racing:france", "bikes:racing:usa", "bikes:racing:italy"); System.out.println(res16); // >>> [] Set res17 = jedis.sdiff("bikes:racing:usa", "bikes:racing:france"); System.out.println(res17); // >>> [bike:4] Set res18 = jedis.sdiff("bikes:racing:france", "bikes:racing:usa"); System.out.println(res18); // >>> [bike:2, bike:3] ``` ##### JavaScript (Node.js) ```javascript await client.del('bikes:racing:france') await client.del('bikes:racing:usa') await client.del('bikes:racing:italy') await client.sAdd('bikes:racing:france', ['bike:1', 'bike:2', 'bike:3']) await client.sAdd('bikes:racing:usa', ['bike:1', 'bike:4']) await client.sAdd('bikes:racing:italy', ['bike:1', 'bike:2', 'bike:3', 'bike:4']) const res14 = await client.sInter( ['bikes:racing:france', 'bikes:racing:usa', 'bikes:racing:italy'] ) console.log(res14) // >>> ['bike:1'] const res15 = await client.sUnion( ['bikes:racing:france', 'bikes:racing:usa', 'bikes:racing:italy'] ) console.log(res15) // >>> ['bike:1', 'bike:2', 'bike:3', 'bike:4'] const res16 = await client.sDiff(['bikes:racing:france', 'bikes:racing:usa', 'bikes:racing:italy']) console.log(res16) // >>> [] const res17 = await client.sDiff(['bikes:racing:usa', 'bikes:racing:france']) console.log(res17) // >>> ['bike:4'] const res18 = await client.sDiff(['bikes:racing:france', 'bikes:racing:usa']) console.log(res18) // >>> ['bike:2', 'bike:3'] ``` ##### PHP ```php $r->del('bikes:racing:france'); $r->del('bikes:racing:usa'); $r->del('bikes:racing:italy'); $r->sadd('bikes:racing:france', ['bike:1', 'bike:2', 'bike:3']); $r->sadd('bikes:racing:usa', ['bike:1', 'bike:4']); $r->sadd('bikes:racing:italy', ['bike:1', 'bike:2', 'bike:3', 'bike:4']); $res14 = $r->sinter(['bikes:racing:france', 'bikes:racing:usa', 'bikes:racing:italy']); echo json_encode($res14) . PHP_EOL; // >>> ["bike:1"] $res15 = $r->sunion(['bikes:racing:france', 'bikes:racing:usa', 'bikes:racing:italy']); sort($res15); echo json_encode($res15) . PHP_EOL; // >>> ["bike:1","bike:2","bike:3","bike:4"] $res16 = $r->sdiff(['bikes:racing:france', 'bikes:racing:usa', 'bikes:racing:italy']); echo json_encode($res16) . PHP_EOL; // >>> [] $res17 = $r->sdiff(['bikes:racing:usa', 'bikes:racing:france']); echo json_encode($res17) . PHP_EOL; // >>> ["bike:4"] $res18 = $r->sdiff(['bikes:racing:france', 'bikes:racing:usa']); sort($res18); echo json_encode($res18) . PHP_EOL; // >>> ["bike:2","bike:3"] ``` ##### Python ```python r.delete("bikes:racing:france") r.delete("bikes:racing:usa") r.delete("bikes:racing:italy") r.sadd("bikes:racing:france", "bike:1", "bike:2", "bike:3") r.sadd("bikes:racing:usa", "bike:1", "bike:4") r.sadd("bikes:racing:italy", "bike:1", "bike:2", "bike:3", "bike:4") res13 = r.sinter("bikes:racing:france", "bikes:racing:usa", "bikes:racing:italy") print(res13) # >>> {'bike:1'} res14 = r.sunion("bikes:racing:france", "bikes:racing:usa", "bikes:racing:italy") print(res14) # >>> {'bike:1', 'bike:2', 'bike:3', 'bike:4'} res15 = r.sdiff("bikes:racing:france", "bikes:racing:usa", "bikes:racing:italy") print(res15) # >>> set() res16 = r.sdiff("bikes:racing:usa", "bikes:racing:france") print(res16) # >>> {'bike:4'} res17 = r.sdiff("bikes:racing:france", "bikes:racing:usa") print(res17) # >>> {'bike:2', 'bike:3'} ``` ##### Ruby ```ruby r.del('bikes:racing:france', 'bikes:racing:usa', 'bikes:racing:italy') r.sadd('bikes:racing:france', ['bike:1', 'bike:2', 'bike:3']) r.sadd('bikes:racing:usa', ['bike:1', 'bike:4']) r.sadd('bikes:racing:italy', ['bike:1', 'bike:2', 'bike:3', 'bike:4']) res14 = r.sinter('bikes:racing:france', 'bikes:racing:usa', 'bikes:racing:italy') puts res14.inspect # >>> ["bike:1"] res15 = r.sunion('bikes:racing:france', 'bikes:racing:usa', 'bikes:racing:italy') puts res15.sort.inspect # >>> ["bike:1", "bike:2", "bike:3", "bike:4"] res16 = r.sdiff('bikes:racing:france', 'bikes:racing:usa', 'bikes:racing:italy') puts res16.inspect # >>> [] res17 = r.sdiff('bikes:racing:france', 'bikes:racing:usa') puts res17.sort.inspect # >>> ["bike:2", "bike:3"] res18 = r.sdiff('bikes:racing:usa', 'bikes:racing:france') puts res18.inspect # >>> ["bike:4"] ``` ##### Rust (Asynchronous) ```rust let _: usize = r .del(&["bikes:racing:france", "bikes:racing:usa", "bikes:racing:italy"]) .await .unwrap_or(0); let _: usize = r .sadd("bikes:racing:france", &["bike:1", "bike:2", "bike:3"]) .await .unwrap_or(0); let _: usize = r .sadd("bikes:racing:usa", &["bike:1", "bike:4"]) .await .unwrap_or(0); let _: usize = r .sadd("bikes:racing:italy", &["bike:1", "bike:2", "bike:3", "bike:4"]) .await .unwrap_or(0); if let Ok(res) = r .sinter(&["bikes:racing:france", "bikes:racing:usa", "bikes:racing:italy"]) .await { let res: HashSet = res; let res = sorted_set(res); println!("{res:?}"); // >>> ["bike:1"] } if let Ok(res) = r .sunion(&["bikes:racing:france", "bikes:racing:usa", "bikes:racing:italy"]) .await { let res: HashSet = res; let res = sorted_set(res); println!("{res:?}"); // >>> ["bike:1", "bike:2", "bike:3", "bike:4"] } if let Ok(res) = r .sdiff(&["bikes:racing:france", "bikes:racing:usa", "bikes:racing:italy"]) .await { let res: HashSet = res; let res = sorted_set(res); println!("{res:?}"); // >>> [] } if let Ok(res) = r.sdiff(&["bikes:racing:france", "bikes:racing:usa"]).await { let res: HashSet = res; let res = sorted_set(res); println!("{res:?}"); // >>> ["bike:2", "bike:3"] } if let Ok(res) = r.sdiff(&["bikes:racing:usa", "bikes:racing:france"]).await { let res: HashSet = res; let res = sorted_set(res); println!("{res:?}"); // >>> ["bike:4"] } ``` ##### Rust (Synchronous) ```rust let _: usize = r.del(&["bikes:racing:france", "bikes:racing:usa", "bikes:racing:italy"]).unwrap_or(0); let _: usize = r.sadd("bikes:racing:france", &["bike:1", "bike:2", "bike:3"]).unwrap_or(0); let _: usize = r.sadd("bikes:racing:usa", &["bike:1", "bike:4"]).unwrap_or(0); let _: usize = r.sadd("bikes:racing:italy", &["bike:1", "bike:2", "bike:3", "bike:4"]).unwrap_or(0); if let Ok(res) = r.sinter(&["bikes:racing:france", "bikes:racing:usa", "bikes:racing:italy"]) { let res: HashSet = res; let res = sorted_set(res); println!("{res:?}"); // >>> ["bike:1"] } if let Ok(res) = r.sunion(&["bikes:racing:france", "bikes:racing:usa", "bikes:racing:italy"]) { let res: HashSet = res; let res = sorted_set(res); println!("{res:?}"); // >>> ["bike:1", "bike:2", "bike:3", "bike:4"] } if let Ok(res) = r.sdiff(&["bikes:racing:france", "bikes:racing:usa", "bikes:racing:italy"]) { let res: HashSet = res; let res = sorted_set(res); println!("{res:?}"); // >>> [] } if let Ok(res) = r.sdiff(&["bikes:racing:france", "bikes:racing:usa"]) { let res: HashSet = res; let res = sorted_set(res); println!("{res:?}"); // >>> ["bike:2", "bike:3"] } if let Ok(res) = r.sdiff(&["bikes:racing:usa", "bikes:racing:france"]) { let res: HashSet = res; let res = sorted_set(res); println!("{res:?}"); // >>> ["bike:4"] } ``` You'll note that the [`SDIFF`](https://redis.io/docs/latest/commands/sdiff) command returns an empty array when the difference between all sets is empty. You'll also note that the order of sets passed to [`SDIFF`](https://redis.io/docs/latest/commands/sdiff) matters, since the difference is not commutative. When you want to remove items from a set, you can use the [`SREM`](https://redis.io/docs/latest/commands/srem) command to remove one or more items from a set, or you can use the [`SPOP`](https://redis.io/docs/latest/commands/spop) command to remove a random item from a set. You can also _return_ a random item from a set without removing it using the [`SRANDMEMBER`](https://redis.io/docs/latest/commands/srandmember) command: Removal strategies: Use SREM for targeted removal, SPOP for random removal, or SRANDMEMBER to inspect without modifying when you need flexible deletion patterns **Difficulty:** Intermediate **Builds upon:** sadd **Commands:** DEL, SADD, SREM, SPOP, SMEMBERS, SRANDMEMBER **Complexity:** - DEL: O(N) - SADD: O(1) - SREM: O(N) - SMEMBERS: O(N) **Available in:** Redis CLI, C#, Go, Java (Asynchronous - Lettuce), Java (Reactive - Lettuce), Java (Synchronous - Jedis), JavaScript (Node.js), PHP, Python, Ruby, Rust (Asynchronous), Rust (Synchronous) ##### Redis CLI ``` > DEL bikes:racing:france (integer) 1 > SADD bikes:racing:france bike:1 bike:2 bike:3 bike:4 bike:5 (integer) 5 > SREM bikes:racing:france bike:1 (integer) 1 > SPOP bikes:racing:france "bike:3" > SMEMBERS bikes:racing:france 1) "bike:2" 2) "bike:4" 3) "bike:5" > SRANDMEMBER bikes:racing:france "bike:2" ``` ##### C# ```csharp db.KeyDelete("bikes:racing:france"); long res27 = db.SetAdd("bikes:racing:france", ["bike:1", "bike:2", "bike:3", "bike:4", "bike:5"]); bool res28 = db.SetRemove("bikes:racing:france", "bike:1"); Console.WriteLine(res28); // >>> True RedisValue res29 = db.SetPop("bikes:racing:france"); Console.WriteLine(res29); // >>> bike:3 RedisValue[] res30 = db.SetMembers("bikes:racing:france"); Console.WriteLine(string.Join(", ", res30)); // >>> bike:2, bike:4, bike:5 RedisValue res31 = db.SetRandomMember("bikes:racing:france"); Console.WriteLine(res31); // >>> bike:4 ``` ##### Go ```go rdb.Del(ctx, "bikes:racing:france") _, err := rdb.SAdd(ctx, "bikes:racing:france", "bike:1", "bike:2", "bike:3", "bike:4", "bike:5").Result() if err != nil { panic(err) } res19, err := rdb.SRem(ctx, "bikes:racing:france", "bike:1").Result() if err != nil { panic(err) } fmt.Println(res19) // >>> 1 res20, err := rdb.SPop(ctx, "bikes:racing:france").Result() if err != nil { panic(err) } fmt.Println(res20) // >>> res21, err := rdb.SMembers(ctx, "bikes:racing:france").Result() if err != nil { panic(err) } fmt.Println(res21) // >>> res22, err := rdb.SRandMember(ctx, "bikes:racing:france").Result() if err != nil { panic(err) } fmt.Println(res22) // >>> ``` ##### Java (Asynchronous - Lettuce) ```java CompletableFuture sRem = asyncCommands .sadd("bikes:racing:france", "bike:1", "bike:2", "bike:3", "bike:4", "bike:5").thenCompose(res22 -> { System.out.println(res22); // >>> 2 return asyncCommands.srem("bikes:racing:france", "bike:1"); }).thenCompose(res23 -> { System.out.println(res23); // >>> 1 return asyncCommands.spop("bikes:racing:france"); }).thenCompose(res24 -> { System.out.println(res24); // >>> bike:3 (for example) return asyncCommands.smembers("bikes:racing:france"); }).thenCompose(res25 -> { System.out.println(res25); // >>> [bike:2, bike:4, bike:5] (for example) return asyncCommands.srandmember("bikes:racing:france"); }).thenAccept(res26 -> { System.out.println(res26); // >>> bike:4 (for example) }).toCompletableFuture(); ``` ##### Java (Reactive - Lettuce) ```java Mono sRem = reactiveCommands.sadd("bikes:racing:france", "bike:1", "bike:2", "bike:3", "bike:4", "bike:5") .doOnNext(result -> { System.out.println(result); // >>> 2 }).flatMap(v -> reactiveCommands.srem("bikes:racing:france", "bike:1")).doOnNext(result -> { System.out.println(result); // >>> 1 }).flatMap(v -> reactiveCommands.spop("bikes:racing:france")).doOnNext(result -> { System.out.println(result); // >>> bike:3 (for example) }).flatMap(v -> reactiveCommands.smembers("bikes:racing:france").collectList()).doOnNext(result -> { System.out.println(result); // >>> [bike:2, bike:4, bike:5] (for example) }).flatMap(v -> reactiveCommands.srandmember("bikes:racing:france")).doOnNext(result -> { System.out.println(result); // >>> bike:4 (for example) }).then(); ``` ##### Java (Synchronous - Jedis) ```java jedis.del("bikes:racing:france"); jedis.sadd("bikes:racing:france", "bike:1", "bike:2", "bike:3", "bike:4", "bike:5"); long res19 = jedis.srem("bikes:racing:france", "bike:1"); System.out.println(res18); // >>> 1 String res20 = jedis.spop("bikes:racing:france"); System.out.println(res20); // >>> bike:3 Set res21 = jedis.smembers("bikes:racing:france"); System.out.println(res21); // >>> [bike:2, bike:4, bike:5] String res22 = jedis.srandmember("bikes:racing:france"); System.out.println(res22); // >>> bike:4 ``` ##### JavaScript (Node.js) ```javascript await client.del('bikes:racing:france') await client.sAdd('bikes:racing:france', ['bike:1', 'bike:2', 'bike:3', 'bike:4', 'bike:5']) const res19 = await client.sRem('bikes:racing:france', 'bike:1') console.log(res19) // >>> 1 const res20 = await client.sPop('bikes:racing:france') console.log(res20) // >>> bike:3 or other random value const res21 = await client.sMembers('bikes:racing:france') console.log(res21) // >>> ['bike:2', 'bike:4', 'bike:5']; depends on previous result const res22 = await client.sRandMember('bikes:racing:france') console.log(res22) // >>> bike:4 or other random value ``` ##### PHP ```php $r->del('bikes:racing:france'); $r->sadd('bikes:racing:france', ['bike:1', 'bike:2', 'bike:3', 'bike:4', 'bike:5']); $res19 = $r->srem('bikes:racing:france', ['bike:1']); echo $res19 . PHP_EOL; // >>> 1 $res20 = $r->spop('bikes:racing:france'); echo $res20 . PHP_EOL; // >>> bike:3 (for example) $res21 = $r->smembers('bikes:racing:france'); sort($res21); echo json_encode($res21) . PHP_EOL; // >>> ["bike:2","bike:4","bike:5"] $res22 = $r->srandmember('bikes:racing:france'); echo $res22 . PHP_EOL; // >>> bike:4 (for example) ``` ##### Python ```python r.delete("bikes:racing:france") r.sadd("bikes:racing:france", "bike:1", "bike:2", "bike:3", "bike:4", "bike:5") res18 = r.srem("bikes:racing:france", "bike:1") print(res18) # >>> 1 res19 = r.spop("bikes:racing:france") print(res19) # >>> bike:3 res20 = r.smembers("bikes:racing:france") print(res20) # >>> {'bike:2', 'bike:4', 'bike:5'} res21 = r.srandmember("bikes:racing:france") print(res21) # >>> bike:4 ``` ##### Ruby ```ruby r.del('bikes:racing:france') r.sadd('bikes:racing:france', ['bike:1', 'bike:2', 'bike:3', 'bike:4', 'bike:5']) res19 = r.srem('bikes:racing:france', ['bike:1']) puts res19 # >>> 1 res20 = r.spop('bikes:racing:france') puts res20 # >>> bike:3, for example res21 = r.smembers('bikes:racing:france') puts res21.sort.inspect # >>> Remaining members, in no particular order res22 = r.srandmember('bikes:racing:france') puts res22 # >>> bike:4, for example ``` ##### Rust (Asynchronous) ```rust let _: usize = r.del("bikes:racing:france").await.unwrap_or(0); let _: usize = r .sadd( "bikes:racing:france", &["bike:1", "bike:2", "bike:3", "bike:4", "bike:5"], ) .await .unwrap_or(0); if let Ok(res) = r.srem("bikes:racing:france", "bike:1").await { let res: usize = res; println!("{res}"); // >>> 1 } if let Ok(res) = r.spop("bikes:racing:france").await { let res: Option = res; match res { Some(res) => println!("{res}"), // >>> bike:3 (for example) None => println!("(nil)"), } } if let Ok(res) = r.smembers("bikes:racing:france").await { let res: HashSet = res; let res = sorted_set(res); println!("{res:?}"); // >>> ["bike:2", "bike:4", "bike:5"] (for example) } if let Ok(res) = r.srandmember("bikes:racing:france").await { let res: Option = res; match res { Some(res) => println!("{res}"), // >>> bike:4 (for example) None => println!("(nil)"), } } ``` ##### Rust (Synchronous) ```rust let _: usize = r.del("bikes:racing:france").unwrap_or(0); let _: usize = r .sadd( "bikes:racing:france", &["bike:1", "bike:2", "bike:3", "bike:4", "bike:5"], ) .unwrap_or(0); if let Ok(res) = r.srem("bikes:racing:france", "bike:1") { let res: usize = res; println!("{res}"); // >>> 1 } if let Ok(res) = r.spop("bikes:racing:france") { let res: Option = res; match res { Some(res) => println!("{res}"), // >>> bike:3 (for example) None => println!("(nil)"), } } if let Ok(res) = r.smembers("bikes:racing:france") { let res: HashSet = res; let res = sorted_set(res); println!("{res:?}"); // >>> ["bike:2", "bike:4", "bike:5"] (for example) } if let Ok(res) = r.srandmember("bikes:racing:france") { let res: Option = res; match res { Some(res) => println!("{res}"), // >>> bike:4 (for example) None => println!("(nil)"), } } ``` ## Limits The max size of a Redis set is 2^32 - 1 (4,294,967,295) members. ## Performance Most set operations, including adding, removing, and checking whether an item is a set member, are O(1). This means that they're highly efficient. However, for large sets with hundreds of thousands of members or more, you should exercise caution when running the [`SMEMBERS`](https://redis.io/docs/latest/commands/smembers) command. This command is O(n) and returns the entire set in a single response. As an alternative, consider the [`SSCAN`](https://redis.io/docs/latest/commands/sscan), which lets you retrieve all members of a set iteratively. ## Alternatives Sets membership checks on large datasets (or on streaming data) can use a lot of memory. If you're concerned about memory usage and don't need perfect precision, consider a [Bloom filter or Cuckoo filter](https://redis.io/docs/latest/develop/data-types/probabilistic/bloom-filter) as an alternative to a set. Redis sets are frequently used as a kind of index. If you need to index and query your data, consider the [JSON](https://redis.io/docs/latest/develop/data-types/json) data type and the [Redis Search](https://redis.io/docs/latest/develop/ai/search-and-query) features. ## Learn more * [Redis Sets Explained](https://www.youtube.com/watch?v=PKdCppSNTGQ) and [Redis Sets Elaborated](https://www.youtube.com/watch?v=aRw5ME_5kMY) are two short but thorough video explainers covering Redis sets. * [Redis University's RU101](https://university.redis.com/courses/ru101/) explores Redis sets in detail.