title: Elasticsearch Segments
body: <p>I have an index with 12 shards allocated in 3 nodes. The index has around 5 millions of elements. Yesterday, these 5 milions of elements had a size of around 35Gb, and if I could reindex all these elements with the new reduced size of each of them, the total size of the index would be around 10Gb.</p>
  
  <p>The problem is that, if I reindex these items inside the existing items, by using upserts, so updating them all, the index size does not reduce at all.</p>
  
  <p>I've been checking the _forcemerge Elasticsearch API, but ATM I'm not using any kind of replicas, and they don't really recommend using this API in a master set of shards.</p>
  
  <p>I'm learning the insides of Elasticsearch, and I'm actually working with a PROD environment, so I can't really clean-and-reindex.</p>
  
  <p>Can anyone send me some light? </p>