OpenSearch/docs/reference/ccr/apis/follow-request-body.asciidoc

[testenv="platinum"]
`settings`::
  (object) Settings to override from the leader index. Note that certain
  settings can not be overrode (e.g., `index.number_of_shards`).

`max_read_request_operation_count`::
  (integer) The maximum number of operations to pull per read from the remote
  cluster.

`max_outstanding_read_requests`::
  (long) The maximum number of outstanding reads requests from the remote
  cluster.

`max_read_request_size`::
  (<<byte-units,byte value>>) The maximum size in bytes of per read of a batch
  of operations pulled from the remote cluster.

`max_write_request_operation_count`::
  (integer) The maximum number of operations per bulk write request executed on
  the follower.

`max_write_request_size`::
  (<<byte-units,byte value>>) The maximum total bytes of operations per bulk write request
  executed on the follower.

`max_outstanding_write_requests`::
  (integer) The maximum number of outstanding write requests on the follower.

`max_write_buffer_count`::
  (integer) The maximum number of operations that can be queued for writing.
  When this limit is reached, reads from the remote cluster will be deferred
  until the number of queued operations goes below the limit.

`max_write_buffer_size`::
  (<<byte-units,byte value>>) The maximum total bytes of operations that can be
  queued for
  writing. When this limit is reached, reads from the remote cluster will be
  deferred until the total bytes of queued operations goes below the limit.

`max_retry_delay`::
  (<<time-units,time value>>) The maximum time to wait before retrying an
  operation that failed exceptionally. An exponential backoff strategy is
  employed when retrying.

`read_poll_timeout`::
  (<<time-units,time value>>) The maximum time to wait for new operations on the
  remote cluster when the follower index is synchronized with the leader index.
  When the timeout has elapsed, the poll for operations will return to the
  follower so that it can update some statistics. Then the follower will
  immediately attempt to read from the leader again.

===== Default values

//////////////////////////

[source,console]
--------------------------------------------------
PUT /follower_index/_ccr/follow?wait_for_active_shards=1
{
  "remote_cluster" : "remote_cluster",
  "leader_index" : "leader_index"
}
--------------------------------------------------
// TESTSETUP
// TEST[setup:remote_cluster_and_leader_index]

[source,console]
--------------------------------------------------
POST /follower_index/_ccr/pause_follow
--------------------------------------------------
// TEARDOWN

[source,console]
--------------------------------------------------
GET /follower_index/_ccr/info?filter_path=follower_indices.parameters
--------------------------------------------------

//////////////////////////

The following output from the follow info api describes all the default
values for the above described index follow request parameters:

[source,console-result]
--------------------------------------------------
{
  "follower_indices" : [
    {
      "parameters" : {
        "max_read_request_operation_count" : 5120,
        "max_read_request_size" : "32mb",
        "max_outstanding_read_requests" : 12,
        "max_write_request_operation_count" : 5120,
        "max_write_request_size" : "9223372036854775807b",
        "max_outstanding_write_requests" : 9,
        "max_write_buffer_count" : 2147483647,
        "max_write_buffer_size" : "512mb",
        "max_retry_delay" : "500ms",
        "read_poll_timeout" : "1m"
      }
    }
  ]
}

--------------------------------------------------