Delete Elasticsearch index, keep mappings/settings

One of the most used problems when I develop against ElasticSearch is that I often require a clean index to debug or investigate an issue.
But that index needs to also keep it’s original settings and mappings so dropping it, is not an option.
Luckily there is an easy workaround that utilises delete_by_query apifrom 5.x
(delete_by_query plugin for previous versions, although they are not even supported nowadays).

Simply run:

curl -XDELETE 'http://localhost:9200/index_name/_doc/_delete_by_query?conflicts=proceed' -d '{
    "query" : { 
        "match_all" : {}
    }
}'

Note 1

conflicts=procceed is needed so that all docs can be removed, even those updated after the execution of above command.

Note 2

As with all heavy queries, ElasticSearch provides a wait_for_completion=false parameter to run it as a _task (not wait for completion but query tasks api).

Note 3

If target contains contains lot of documents, it might be easier to drop and recreate that index. Delete_by_query doesn’t immediately remove documents,
it marks them for deletion so they do not appear when searching but actual deletion from disk space happens way after in segment merge.

More here