title: Larger index size after Elasticsearch reindex
body: <p>After performing a reindex on a 75GB index, the new one went to 79GB.</p>
  
  <p>Both indexes have the same doc count (54,123,676) and both have the exact same mapping. The original index has 6*2 shards and the new one has 3*2 shards.</p>
  
  <p>The original index also has 75,857 deleted documents which were not moved across, so we are pretty stumped as to how it could even be smaller than the new one at all, let alone by a whole 4GB.</p>
  
  <p><strong>Original Index</strong></p>
  
  <pre><code>{
      "_shards": {
          "total": 12,
          "successful": 12,
          "failed": 0
      },
      "_all": {
          "primaries": {
              "docs": {
                  "count": 54123676,
                  "deleted": 75857
              },
              "store": {
                  "size_in_bytes": 75357819717,
                  "throttle_time_in_millis": 0
              },
              ...
              "segments": {
                  "count": 6,
                  "memory_in_bytes": 173650124,
                  "terms_memory_in_bytes": 152493380,
                  "stored_fields_memory_in_bytes": 17914688,
                  "term_vectors_memory_in_bytes": 0,
                  "norms_memory_in_bytes": 79424,
                  "points_memory_in_bytes": 2728328,
                  "doc_values_memory_in_bytes": 434304,
                  "index_writer_memory_in_bytes": 0,
                  "version_map_memory_in_bytes": 0,
                  "fixed_bit_set_memory_in_bytes": 0,
                  "max_unsafe_auto_id_timestamp": -1,
                  "file_sizes": {}
              }
              ...
  </code></pre>
  
  <p><strong>New Index</strong></p>
  
  <pre><code>{
      "_shards": {
          "total": 6,
          "successful": 6,
          "failed": 0
      },
      "_all": {
          "primaries": {
              "docs": {
                  "count": 54123676,
                  "deleted": 0
              },
              "store": {
                  "size_in_bytes": 79484557149,
                  "throttle_time_in_millis": 0
              },
              ...
              "segments": {
                  "count": 3,
                  "memory_in_bytes": 166728713,
                  "terms_memory_in_bytes": 145815659,
                  "stored_fields_memory_in_bytes": 17870464,
                  "term_vectors_memory_in_bytes": 0,
                  "norms_memory_in_bytes": 37696,
                  "points_memory_in_bytes": 2683802,
                  "doc_values_memory_in_bytes": 321092,
                  "index_writer_memory_in_bytes": 0,
                  "version_map_memory_in_bytes": 0,
                  "fixed_bit_set_memory_in_bytes": 0,
                  "max_unsafe_auto_id_timestamp": -1,
                  "file_sizes": {}
              }
              ...
  </code></pre>
  
  <p>Any clues?</p>