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.
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`.
The split index API operation creates a new target index, so you can specify any [index settings]({{site.url}}{{site.baseurl}}/api-reference/index-apis/create-index/#index-settings) and [aliases]({{site.url}}{{site.baseurl}}/opensearch/index-alias) to apply to the target index.