Throttle a reindex operation

POST /_reindex/{task_id}/_rethrottle

Auth

Change the maximum number of documents to index per second for a particular reindex operation. For example, to unthrottle to unlimited documents per second:

POST _reindex/r1A2WoRbTwKZ516z6NEs5A:36619/_rethrottle?requests_per_second=-1

Rethrottling that speeds up the query takes effect immediately. Rethrottling that slows down the query will take effect after completing the current batch of documents. This behavior prevents scroll timeouts.

This API follows reindex tasks across node-shutdown relocations, so callers can keep using the original task ID throughout the lifetime of the operation. The relocated task ID is also accepted and is followed transparently. In either case, returned task IDs and timings reflect the original task, not its relocated successor.

The rethrottle may not have been applied to any tasks if either node_failures or task_failures are non-empty, or if the response contains no successfully rethrottled tasks — that is, no entries under nodes (returned with the default group_by=nodes in stack) or under tasks (returned in serverless, or in stack with group_by=none or group_by=parents).

Required privileges

Cluster privileges manage_reindex

Path parameters

task_id string required: The task identifier, returned when creating a reindex task, or by listing tasks via GET /_reindex or GET /_tasks. In stack, can be either the original task ID or the task ID of the relocated task.

Query parameters

requests_per_second number required

The maximum number of documents to index per second, across the entire reindex operation (including slices). It can be either -1 to turn off throttling or any decimal number like 1.7 or 12 to throttle to that level.

group_by enum · default: nodes

The way to group the tasks in the response. We recommend setting this to none, which provides the cleanest response format.

Supported values include:

nodes: Group tasks by node ID.
parents: Group tasks by parent task ID.
none: Do not group tasks.

Values: nodes parents none

Response

application/json

node_failures object[]: Node-level failures encountered while applying the rethrottle request. Will return a failed_node_exception wrapping a no_such_node_exception, if a node handling the task either never existed, or has left the cluster, and one of the following is true:

The task has completed.

The task cannot be found.

Note

Rethrottle handles relocations, so it should succeed if the task can be found and has not completed.
task_failures object[]: Per-task failures encountered while applying the rethrottle. If a rethrottle is attempted during a relocation handoff, the failure object reports status: SERVICE_UNAVAILABLE (the HTTP response itself is still 200 OK). In this case, the request can be retried until success.
nodes map string to object: Tasks grouped by node, returned only when group_by=nodes (the default).
tasks union oneOf: The tasks that were successfully rethrottled. Always returned in serverless. Returned with group_by=none or group_by=parents in stack.; One of: