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XINFO STREAM

Introduction​

In Dragonfly, as well as in Redis and Valkey, the XINFO STREAM command provides information about a specific stream. This is particularly useful for monitoring and debugging streams, as it helps you understand the structure and state of a stream.

Syntax​

XINFO STREAM key

Parameter Explanations​

  • key: The key of the stream for which information is to be retrieved.

Return Values​

The command returns a list of key-value pairs providing information about the specified stream's state and elements.

Code Examples​

Retrieve Stream Information​

Get information about a stream:

dragonfly$> XADD mystream * sensor-id 1234 temperature 19.8
"1632494980015-0"
dragonfly$> XINFO STREAM mystream
 1) "length"
 2) (integer) 1
 3) "radix-tree-keys"
 4) (integer) 1
 5) "radix-tree-nodes"
 6) (integer) 2
 7) "groups"
 8) (integer) 0
 9) "last-generated-id"
10) "1632494980015-0"
11) "first-entry"
12) 1) "1632494980015-0"
    2) 1) "sensor-id"
       2) "1234"
       3) "temperature"
       4) "19.8"
13) "last-entry"
14) 1) "1632494980015-0"
    2) 1) "sensor-id"
       2) "1234"
       3) "temperature"
       4) "19.8"

Best Practices​

  • Regularly use XINFO STREAM to monitor the health and performance of streams.
  • Analyze the output to optimize memory and understand stream usage patterns.

Common Mistakes​

  • Not grasping the meaning of each output field; ensure you understand terms like "radix-tree-keys" and "last-generated-id".
  • Forgetting that XINFO STREAM only queries data and does not modify the stream content.

FAQs​

What does "radix-tree-keys" signify?​

"radix-tree-keys" indicates the number of entries in the underlying radix tree data structure, which can help assess memory use.

How do I interpret "first-entry" and "last-entry"?​

"first-entry" and "last-entry" give you the stream's start and end records, which are important for identifying the current pattern of data.