Deprecated in 2.1.0.

Optimize API has been renamed to the force merge API

The optimize API allows to optimize one or more indices through an API. The optimize process basically optimizes the index for faster search operations (and relates to the number of segments a Lucene index holds within each shard). The optimize operation allows to reduce the number of segments by merging them.

This call will block until the optimize is complete. If the http connection is lost, the request will continue in the background, and any new requests will block until the previous optimize is complete.

$ curl -XPOST 'http://localhost:9200/twitter/_optimize'

Request Parametersedit

The optimize API accepts the following request parameters as query arguments:


The number of segments to optimize to. To fully optimize the index, set it to 1. Defaults to simply checking if a merge needs to execute, and if so, executes it.


Should the optimize process only expunge segments with deletes in it. In Lucene, a document is not deleted from a segment, just marked as deleted. During a merge process of segments, a new segment is created that does not have those deletes. This flag allows to only merge segments that have deletes. Defaults to false. Note that this won’t override the index.merge.policy.expunge_deletes_allowed threshold.


Should a flush be performed after the optimize. Defaults to true.

Multi Indexedit

The optimize API can be applied to more than one index with a single call, or even on _all the indices.

$ curl -XPOST 'http://localhost:9200/kimchy,elasticsearch/_optimize'

$ curl -XPOST 'http://localhost:9200/_optimize?only_expunge_deletes=true'