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ElasticSearch–Reindex API

At first when I had to recreate or change an index in ElasticSearch I used a rather naïve approach. I deleted and recreated my index and start processing all data again from the original source.

This approach worked but put a lot of stress on the network and ElasticSearch nodes.

A better solution is to use the reindex API. It enables you to reindex your documents without requiring any plugin nor external tool.

Thanks to the existence of the _source field you already have the whole document available to you in Elasticsearch itself. This means you can start from your existing index and use the reindex API to create a new index next to it:

POST _reindex
{
  "source": {
    "index": "twitter"
  },
  "dest": {
    "index": "new_twitter"
  }
}

Remark: Reindex does not attempt to set up the destination index. You should set up the destination index prior to running a _reindex action, including setting up mappings, shard counts, replicas, etc.

More information: https://www.elastic.co/guide/en/elasticsearch/reference/current/docs-reindex.html

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