XREAD command is used in Redis Streams when a client wants to consume data. It allows for both blocking and non-blocking reads from one or multiple streams. This is particularly useful when you need to process stream data in real-time, such as in a chat application, tracking user activity, or handling event-driven architectures.
Consider an application where we are using the Node Redis client library and want to read from a Redis Stream named "mystream".
In this example, we are using the
BLOCK option with a timeout of 0, indicating that it will wait indefinitely for new data. The dollar sign
$ indicates that we want to read any new messages that arrive after initiating this command.
In this instance, we're performing a non-blocking read. The '0' indicates that we want to start reading from the beginning of the stream.
XREAD BLOCK) with caution. It's often better to implement polling with a pause instead of using indefinite blocking reads (
BLOCK0) that could potentially tie up a connection indefinitely.
XREAD, be aware that it returns an array of results, not a single result. Even if you're reading from just one stream, you need to handle the returned data accordingly.
Q: Can we read from multiple streams using XREAD in Node?
Yes, you can add more stream IDs to the 'STREAMS' option like so: