Pipelines and transactions

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]({{< relref "/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]({{< relref "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:

{{< clients-example set="pipe_trans_tutorial" step="basic_pipe" lang_filter="Rust-Sync" description="Foundational: Use pipelines to batch multiple commands together and reduce network round trips" difficulty="beginner" >}} {{< /clients-example >}}

Execute a transaction

You can execute a simple transaction by adding the atomic() method to a pipeline.

{{< clients-example set="pipe_trans_tutorial" step="basic_trans" lang_filter="Rust-Sync" description="Foundational: Use transactions to execute multiple commands atomically without interruption from other clients" difficulty="beginner" >}} {{< /clients-example >}}

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]({{< relref "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.

{{< clients-example set="pipe_trans_tutorial" step="trans_watch" lang_filter="Rust-Sync" description="Optimistic locking: Monitor keys for changes and retry the transaction when conflicts occur" difficulty="intermediate" >}} {{< /clients-example >}}