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 asynchronous versions of the standard command methods (for example, StringSetAsync() and StringGetAsync()). The commands are buffered in the pipeline and only execute when you call the Execute() method on the pipeline object.

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

Execute a transaction

A transaction works in a similar way to a pipeline. Create an instance of the Transaction class, call async command methods on that object, and then call the transaction object's Execute() method to execute it.

{{< clients-example set="pipe_trans_tutorial" step="basic_trans" lang_filter="C#-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 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 approach to optimistic locking that other clients use (adding the [WATCH]({{< relref "/commands/watch" >}}) command explicitly to a transaction) doesn't work well with the [multiplexing]({{< relref "/develop/clients/pools-and-muxing" >}}) system that NRedisStack uses. Instead, NRedisStack relies on conditional execution of commands to get a similar effect.

Use the AddCondition() method to abort a transaction if a particular condition doesn't hold throughout its execution. If the transaction does abort then the Execute() method returns a false value, but otherwise returns true.

For example, the KeyNotExists condition aborts the transaction if a specified key exists or is added by another client while the transaction executes:

{{< clients-example set="pipe_trans_tutorial" step="trans_watch" lang_filter="C#-Sync" description="Optimistic locking: Use conditions to monitor keys for changes and abort transactions when conflicts occur" difficulty="intermediate" >}} {{< /clients-example >}}

You can also use a When condition on certain individual commands to specify that they only execute when a certain condition holds (for example, the command does not change an existing key). See [Conditional execution]({{< relref "/develop/clients/dotnet/condexec" >}}) for a full description of transaction and command conditions.