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Split index

The split index API operation splits an existing read-only index into a new index, cutting each primary shard into some amount of primary shards in the new index.


PUT /sample-index1/_split/split-index1
  "settings": {
    "index": {
      "number_of_shards": 4,
      "number_of_replicas": 2
  "aliases": {
    "sample-alias1": {}

Path and HTTP methods

POST /<source-index>/_split/<target-index>
PUT /<source-index>/_split/<target-index>

Index naming restrictions

OpenSearch indexes have the following naming restrictions:

  • All letters must be lowercase.
  • Index names can’t begin with underscores (_) or hyphens (-).
  • Index names can’t contain spaces, commas, or the following characters:

    :, ", *, +, /, \, |, ?, #, >, or <

URL parameters

Your request must include the source and target indexes. All split index parameters are optional.

Parameter Type Description
<source-index> String The source index to split.
<target-index> String The index to create.
wait_for_active_shards String The number of active shards that must be available before OpenSearch processes the request. Default is 1 (only the primary shard). Set to all or a positive integer. Values greater than 1 require replicas. For example, if you specify a value of 3, the index must have two replicas distributed across two additional nodes for the operation to succeed.
master_timeout Time How long to wait for a connection to the master node. Default is 30s.
timeout Time How long to wait for the request to return. Default is 30s.
wait_for_completion Boolean When set to false, the request returns immediately instead of after the operation is finished. To monitor the operation status, use the Tasks API with the task ID returned by the request. Default is true.
task_execution_timeout Time The explicit task execution timeout. Only useful when wait_for_completion is set to false. Default is 1h.

Request body

The split index API operation creates a new target index, so you can specify any index settings and aliases to apply to the target index.


    "acknowledged": true,
    "shards_acknowledged": true,
    "index": "split-index1"
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