elasticsearchHow do I reindex my data in Elasticsearch?

Reindexing in Elasticsearch is the process of changing the existing index structure or settings. This can be done in two ways:

1. Using the Reindex API:

The Reindex API allows you to copy documents from one index to another, possibly changing the index settings and/or the mapping along the way.

Example

POST _reindex
{
  "source": {
    "index": "my_source_index"
  },
  "dest": {
    "index": "my_dest_index"
  }
}

Output example

{
  "took": 9,
  "timed_out": false,
  "_scroll_id": "DXF1ZXJ5QW5kRmV0Y2gBAAAAAAAAAD4WYm9laVYtZndUQlNsdDcwakFMNjU1QQ==",
  "total": 5,
  "updated": 0,
  "created": 5,
  "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
}

The parts of the code are:

• The POST command, to send the request to the server.
• The _reindex endpoint, which is the Elasticsearch API used for reindexing.
• The source and dest objects, which define the source and destination indices.
• Parameters such as _scroll_id, total, created, and deleted, which provide information about the reindexing process.

2. Using Logstash:

Logstash is a data processing pipeline that allows you to transform data from one format to another. You can use Logstash to reindex Elasticsearch data by setting up a pipeline that reads from the source index, transforms the data if needed, and then writes to the destination index.

Helpful links

• Reindex API
• Logstash Documentation

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