10. Miscellaneous

Overview

Elasticsearch has a lot more functionality that one could cover in a short course! This page is to bring in those important concepts that are expected to be useful when working with Elasticsearch.

Reindexing Data

Reindexing is an operation where the data in an existing index can be refreshed or copying from one index to an other. Surely the data is expected to be changing over time, for example, adding additional fields or correcting the existing data etc.

As expected, Elasticsearch provides reindexing API with _reindex endpoint, which takes in a source and a target.

POST _reindex
{
  "source": {
    "index": "books"
  },
  "dest": {
    "index": "old_books"
  }
}

// Response
{
  "took" : 1760,
  "timed_out" : false,
  "total" : 9,
  "updated" : 0,
  "created" : 9,
  "deleted" : 0,
  "batches" : 1,
  "version_conflicts" : 0,
  "noops" : 0,
  "retries" : {
    "bulk" : 0,
    "search" : 0
  },
  "throttled_millis" : 0,
  "requests_per_second" : -1.0,
  "throttled_until_millis" : 0,
  "failures" : [ ]
}