REPLCONF

Introduction and Use Case(s)

REPLCONF is a command used in Redis replication to configure settings for the replication link between a master and its replicas. It is typically employed during the initial synchronization process or when changing runtime parameters of the replication link. Scenarios include adjusting buffer sizes, setting offsets, and managing acknowledgments.

Syntax

  1. REPLCONF <option> [value]

Parameter Explanations

  • option: The configuration option to set. Common options include:

    • listening-port: Sets the port on which the replica listens.
    • ack: Acknowledges the receipt of replication data up to a specified offset.
    • getack: Requests an acknowledgment from the replica.
  • value: The value to be assigned to the given option. This varies based on the chosen option.

Return Values

The return value of REPLCONF depends on the specific option used:

  • For ack and getack options, it typically returns an OK if successful.
  • Invalid options or values generate error messages.

Example:

  1. dragonfly> REPLCONF listening-port 6380
  2. OK
  3. dragonfly> REPLCONF ack 12345
  4. OK

Code Examples

  1. dragonfly> REPLCONF listening-port 6380
  2. OK
  3. dragonfly> REPLCONF ack 12345
  4. OK
  5. dragonfly> REPLCONF getack
  6. (null)

Best Practices

  • Ensure you understand the exact role each replication configuration parameter plays in your high availability setup.
  • Use REPLCONF to fine-tune replication performance and reliability based on your network characteristics.

Common Mistakes

Using Incorrect Option Names

Using an unsupported or misspelled option name will result in an error. Always refer to official documentation for supported options.

  1. dragonfly> REPLCONF unkown-option 1234
  2. (error) ERR unknown option 'unkown-option'

Incorrect Value Types

Providing values that do not match the expected type or format for a given option can also lead to errors. Make sure the values align with what the option expects.

FAQs

What happens if I use an unknown option?

Redis will return an error indicating that the option is unknown.

Can REPLCONF be used by normal clients?

No, it is intended for internal replication management and should be used within the context of Redis’ built-in replication mechanisms.