Updating Documents | Indexing Data | Elasticsearch Tutorial

Introduction

Elasticsearch is a powerful search engine that allows you to perform and combine many types of searches such as structured, unstructured, geo, and metric. One of the key features of Elasticsearch is its ability to update documents. This tutorial will guide you through the process of updating documents in Elasticsearch from start to finish.

Prerequisites

Before you can update documents in Elasticsearch, you need to have the following:

Elasticsearch installed and running on your local machine or server
A basic understanding of Elasticsearch indices and documents
cURL or any other HTTP client tool for making requests

Updating a Document

To update a document in Elasticsearch, you can use the _update API. This endpoint allows you to update a document by specifying the document ID.

Here is an example of updating a document using cURL:

curl -X POST "localhost:9200/index_name/_update/document_id" -H 'Content-Type: application/json' -d'
{
  "doc": {
    "field": "new_value"
  }
}'

The _update API supports partial updates, which means you only need to specify the fields you want to update.

Example: Updating a User's Email

Let's assume you have an index named users and a document with ID 1 that represents a user. You want to update the user's email address. Here is how you can do it:

curl -X POST "localhost:9200/users/_update/1" -H 'Content-Type: application/json' -d'
{
  "doc": {
    "email": "new_email@example.com"
  }
}'

{
  "_index": "users",
  "_type": "_doc",
  "_id": "1",
  "_version": 2,
  "result": "updated",
  "_shards": {
    "total": 2,
    "successful": 1,
    "failed": 0
  },
  "_seq_no": 1,
  "_primary_term": 1
}

The response indicates that the document was successfully updated, and the version number has been incremented.

Using Scripts to Update Documents

Sometimes you may want to update a document using a script. Elasticsearch supports this via the script field in the update request. Here is an example:

curl -X POST "localhost:9200/users/_update/1" -H 'Content-Type: application/json' -d'
{
  "script" : {
    "source": "ctx._source.age += params.years",
    "lang": "painless",
    "params" : {
      "years" : 1
    }
  }
}'

This example increments the user's age by 1 year using a Painless script.

Conclusion

Updating documents in Elasticsearch is a straightforward process that can be accomplished using the _update API. Whether you need to update specific fields or use scripts to manipulate data, Elasticsearch provides the flexibility to handle various update scenarios. By understanding how to update documents, you can ensure your Elasticsearch indices stay current with the latest information.