emqx4.3/examples/retainer.conf.example

##--------------------------------------------------------------------
## Retainer
##
## Configuration related to handling PUBLISH packets with a retain flag set to 1
##--------------------------------------------------------------------
## Note: This is an example of how to configure this feature
##       you should copy and paste the below data into the emqx.conf for working

retainer {
    ## set to false to disable this
    enable = true

    ## Message retention time. 0 means message will never be expired
    msg_expiry_interval = 0s

    ## Periodic interval for cleaning up expired messages. Never clear if the value is 0
    msg_clear_interval = 0s

    ## Maximum retained message size
    max_payload_size = 1MB

    ## When the retained flag of the PUBLISH message is set and Payload is empty, whether to continue to publish the message
    stop_publish_clear_msg = false

    ## Maximum retained messages delivery rate per session
    deliver_rate = "1000/s"

    ## Retained messages store backend
    backend {
      ## Backend type
      type = built_in_database

      ## Specifies whether the messages are stored in RAM or persisted on disc
      ## Type: enum: ram | disc
      storage_type = ram

      ## Maximum number of retained messages. 0 means no limit
      max_retained_messages = 0
     }
 }