XPENDING command in Redis is commonly used to obtain detailed information on pending messages of a stream’s consumer group. This is especially useful in situations where you are dealing with data streams and have consumers that may fail or delay processing.
Let's assume we have a stream named
my_stream and a consumer group
To begin with, we'll need to set up a connection to the Redis server:
Then, to use XPENDING, you might do something like this:
This will return an array containing the number of pending messages for the group and additional details such as the highest and lowest message ID and consumer names.
xPending, always make sure you are passing in the correct parameters in the correct order — first the stream name and then the group name.
Q: Will XPENDING lock the pending messages while they are being fetched?
A: No, XPENDING only fetches the metadata of the pending messages. It doesn't lock them or prevent other consumers from processing those messages.