# Pipelines and transactions ```json metadata { "schema_version": 2, "title": "Pipelines and transactions", "description": "Learn how to use Redis pipelines and transactions", "categories": ["docs","develop","stack","oss","rs","rc","oss","kubernetes","clients"], "tableOfContents": {"sections":[{"id":"execute-a-pipeline","title":"Execute a pipeline"},{"id":"execute-a-transaction","title":"Execute a transaction"},{"id":"watch-keys-for-changes","title":"Watch keys for changes"}]} , "codeExamples": [{"codetabsId":"pipe_trans_tutorial-stepbasic_pipe","description":"Foundational: Use pipelines to batch multiple commands together and reduce network round trips","difficulty":"beginner","id":"basic_pipe","languages":[{"clientId":"redis-rs","clientName":"redis-rs","id":"Rust-Sync","langId":"rust","panelId":"panel_Rust-Sync_pipe_trans_tutorial-stepbasic_pipe"}]},{"codetabsId":"pipe_trans_tutorial-stepbasic_trans","description":"Foundational: Use transactions to execute multiple commands atomically without interruption from other clients","difficulty":"beginner","id":"basic_trans","languages":[{"clientId":"redis-rs","clientName":"redis-rs","id":"Rust-Sync","langId":"rust","panelId":"panel_Rust-Sync_pipe_trans_tutorial-stepbasic_trans"}]},{"codetabsId":"pipe_trans_tutorial-steptrans_watch","description":"Optimistic locking: Monitor keys for changes and retry the transaction when conflicts occur","difficulty":"intermediate","id":"trans_watch","languages":[{"clientId":"redis-rs","clientName":"redis-rs","id":"Rust-Sync","langId":"rust","panelId":"panel_Rust-Sync_pipe_trans_tutorial-steptrans_watch"}]}] } ``` ## 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. --- Redis lets you send a sequence of commands to the server together in a batch. There are two types of batch that you can use: - **Pipelines** avoid network and processing overhead by sending several commands to the server together in a single communication. The server then sends back a single communication with all the responses. See the [Pipelining](https://redis.io/docs/latest/develop/using-commands/pipelining) page for more information. - **Transactions** guarantee that all the included commands will execute to completion without being interrupted by commands from other clients. See the [Transactions](https://redis.io/docs/latest/develop/using-commands/transactions) page for more information. ## Execute a pipeline To execute commands in a pipeline, you first create a pipeline object and then add commands to it using methods that resemble the standard command methods (for example, `set()` and `get()`). The commands are buffered in the pipeline and only execute when you call the `exec()` method on the pipeline object. If you need the results from the commands, use the `query()` method, which returns the results from all the commands in order. Note that the command methods for a pipeline always return the original pipeline object, so you can "chain" several commands together, as the example below shows: Foundational: Use pipelines to batch multiple commands together and reduce network round trips **Difficulty:** Beginner **Available in:** Rust (Synchronous) ##### Rust (Synchronous) ```rust // Check the success of the pipeline without checking the results // individually. match redis::pipe() .set("seat:0", "#0") .set("seat:1", "#1") .set("seat:2", "#2") .set("seat:3", "#3") .set("seat:4", "#4") .exec(&mut r) { Ok(_) => { println!("Pipe executed successfully"); }, Err(e) => { println!("Error executing pipe: {e}"); return; } }; // Check the success of the pipeline and the results individually. let (seat_0, seat_1, seat_2, seat_3, seat_4) : (String, String, String, String, String) = match redis::pipe() .get("seat:0") .get("seat:1") .get("seat:2") .get("seat:3") .get("seat:4") .query(&mut r) { Ok(res) => res, Err(e) => { println!("Error executing pipe: {e}"); return; } }; println!("{seat_0}, {seat_1}, {seat_2}, {seat_3}, {seat_4}"); // >>> #0, #1, #2, #3, #4 // Use `ignore()` to ignore the result of specific commands. let (seat_5, seat_6, seat_7) : (String, String, String) = match redis::pipe() .set("seat:5", "#5").ignore() .set("seat:6", "#6").ignore() .set("seat:7", "#7").ignore() .get("seat:5") .get("seat:6") .get("seat:7") .query(&mut r) { Ok(res) => res, Err(e) => { println!("Error executing pipe: {e}"); return; } }; println!("{seat_5}, {seat_6}, {seat_7}"); // >>> #5, #6, #7 ``` ## Execute a transaction You can execute a simple transaction by adding the `atomic()` method to a pipeline. Foundational: Use transactions to execute multiple commands atomically without interruption from other clients **Difficulty:** Beginner **Available in:** Rust (Synchronous) ##### Rust (Synchronous) ```rust match redis::pipe() .atomic() .incr("counter:1", 1) .incr("counter:2", 2) .incr("counter:3", 3) .exec(&mut r) { Ok(_) => { println!("Transaction executed successfully"); }, Err(e) => { println!("Error executing transaction: {e}"); return; } }; ``` ## Watch keys for changes Redis supports *optimistic locking* to avoid inconsistent updates to different keys. The basic idea is to watch for changes to any keys that you use in a transaction while you are processing the updates. If the watched keys do change, you must restart the updates with the latest data from the keys. See [Transactions](https://redis.io/docs/latest/develop/using-commands/transactions) for more information about optimistic locking. The example below shows how to use the `transaction()` function to automatically retry a transaction when watched keys are modified. Pass the list of keys you want to watch and a closure representing the transaction. The closure receives the original connection and a pipeline as parameters. Use the connection to read the latest values from the watched keys, but always use the pipeline to add all the commands that make up the watched transaction. If the watched keys are modified during the transaction, the `transaction()` function automatically retries the transaction until it succeeds. Optimistic locking: Monitor keys for changes and retry the transaction when conflicts occur **Difficulty:** Intermediate **Available in:** Rust (Synchronous) ##### Rust (Synchronous) ```rust let key = "shellpath"; let _: () = r.set(key, "/usr/syscmds/").unwrap(); let Ok(_,): Result<((),), _> = redis::transaction(&mut r, &[key], |r, pipe| { let mut path: String = r.get(key).unwrap(); path.push_str(":/usr/mycmds/"); pipe.set(key, path).query(r) }) else { println!("Error executing transaction"); return; }; match r.get("shellpath") { Ok(res) => { let res: String = res; println!("{res}"); // >>> /usr/syscmds/:/usr/mycmds/ }, Err(e) => { println!("Error getting shellpath: {e}"); return; } }; ```