elasticsearch: how to free store size after deleting documents

Question

On my elasticsearch server: total documents: 3 million, total size: 3.6G Then, I delete about 2.8 millions documents: total documents: about 0.13 million, total size: 3.6G

Answer 1

In the current elasticsearch version(7.5),

1. To optimize all indices:

   POST /_forcemerge?only_expunge_deletes=true

2. To optimize single index

   POST /twitter/_forcemerge?only_expunge_deletes=true , where twitter is the index

3. To optimize several indices

   POST /twitter,facebook/_forcemerge?only_expunge_deletes=true , where twitter and facebook are the indices

Reference: https://www.elastic.co/guide/en/elasticsearch/reference/7.5/indices-forcemerge.html#indices-forcemerge