Document ID strategies (auto vs manual) in Elasticsearch

Introduction

Document IDs help find and update data quickly in Elasticsearch. You can let Elasticsearch create them automatically or set your own IDs.

When you want Elasticsearch to handle unique IDs for you automatically.

When you have a unique key from your data and want to use it as the document ID.

When you need to update or delete documents by a known ID.

When you want to avoid duplicate documents by controlling the ID.

When you want to link documents with meaningful IDs for easier searching.

Syntax

Elasticsearch

POST /index_name/_doc
{
  "field": "value"
}

POST /index_name/_doc/document_id
{
  "field": "value"
}

Without specifying an ID, Elasticsearch creates one automatically.

To set your own ID, add it after the index and _doc in the URL.

Examples

Elasticsearch creates a unique ID automatically for this new product.

Elasticsearch

POST /products/_doc
{
  "name": "Coffee Mug",
  "price": 12.99
}

We set the document ID to '12345' manually for easy reference later.

Elasticsearch

POST /products/_doc/12345
{
  "name": "Tea Cup",
  "price": 9.99
}

Retrieve the document with the manual ID '12345'.

Elasticsearch

GET /products/_doc/12345

Sample Program

This example adds two books to the 'library' index. The first book gets an automatic ID. The second book uses a manual ID 'book-001'. Then it retrieves the second book by its manual ID.

Elasticsearch

POST /library/_doc
{
  "title": "Elasticsearch Basics",
  "author": "Jane Doe"
}

POST /library/_doc/book-001
{
  "title": "Advanced Elasticsearch",
  "author": "John Smith"
}

GET /library/_doc/book-001

Important Notes

Manual IDs let you update or delete documents easily by ID.

Automatic IDs are good when you don't have a unique key and want Elasticsearch to handle uniqueness.

Using manual IDs incorrectly can cause overwriting documents if IDs repeat.

Summary

Document IDs identify each document uniquely in Elasticsearch.

You can let Elasticsearch create IDs automatically or set your own manual IDs.

Manual IDs help with updates and avoiding duplicates but require careful management.