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PING

Syntax​

PING [message]

Time complexity: O(1)

Returns PONG if no argument is provided, otherwise return a copy of the argument as a bulk. This command is useful for:

  1. Testing whether a connection is still alive.
  2. Verifying the server's ability to serve data - an error is returned when this isn't the case (e.g., during load from persistence or accessing a stale replica).
  3. Measuring latency.

If the client is subscribed to a channel or a pattern, it will instead return a multi-bulk with a "pong" in the first position and an empty bulk in the second position, unless an argument is provided in which case it returns a copy of the argument.

Return​

Simple string reply, and specifically PONG, when no argument is provided.

Bulk string reply the argument provided, when applicable.

Examples​

dragonfly> PING
"PONG"
dragonfly> PING "hello world"
"hello world"