Elasticsearch CRUD Commands

Welcome to this comprehensive lesson on Elasticsearch CRUD commands. In this guide, we demonstrate how to create, update, retrieve, and delete indices and documents through Kibana’s DevTools interface. Follow the sections below to learn how to interact with Elasticsearch using various commands.

The Kibana UI provides an intuitive editor where you can send requests to Elasticsearch. The left pane is for entering commands, while the right pane displays the corresponding output. Let’s dive in.

Searching All Documents

To retrieve all documents from Elasticsearch, run the following command:

GET _search
{
  "query": {
    "match_all": {}
  }
}

Checking Cluster Health

Before executing any modifications, it is advisable to verify the health of your Elasticsearch cluster. Run this GET request to check the cluster's status:

GET /_cluster/health

A successful response (HTTP status 200) returns details similar to the example below:

{
  "cluster_name": "elasticsearch",
  "status": "yellow",
  "timed_out": false,
  "number_of_nodes": 1,
  "number_of_data_nodes": 1,
  "active_primary_shards": 10,
  "active_shards": 10,
  "relocating_shards": 0,
  "initializing_shards": 0,
  "unassigned_shards": 2,
  "delayed_unassigned_shards": 0,
  "number_of_pending_tasks": 0,
  "number_of_in_flight_fetch": 0,
  "task_max_waiting_in_queue_millis": 0,
  "active_shards_percent_as_number": 83.33333333333334
}

Creating an Index

To create a new index named "products", execute the following PUT command:

PUT /products

On successful execution, you will receive an acknowledgement confirming the creation of the "products" index.

Adding a Document

Insert a new document into the "products" index using the POST command. The example below adds a product document with multiple properties:

POST /products/_doc/1
{
  "product_id": 67890,
  "name": "Cozy Winter Sweater",
  "description": "Soft and stylish sweater for cold days",
  "price": 59.99,
  "category": "Apparel",
  "brand": "Trendy Threads"
}

Retrieving the Document

To confirm that the document has been added, retrieve it with the following GET command:

GET /products/_doc/1

You can also search for the document by matching specific fields. For example, to find a product with "sweater" in its name, use:

GET /products/_search
{
  "query": {
    "match": {
      "name": "sweater"
    }
  }
}

In the response, note that the document data is stored under the "_source" key, while other keys hold metadata.

Updating a Document

Incorrect Approach Using PUT

Attempting to update a document using the PUT command may result in issues, as it replaces the entire document rather than updating specific fields. For example:

PUT /products/_doc/1
{
  "price": 129.99
}

This approach can trigger a parsing exception (HTTP status 400) if not formatted correctly.

Correct Approach Using POST with _update

To modify only specific fields without replacing the entire document, use the POST command with the _update endpoint. First, ensure your document exists:

POST /products/_doc/1
{
  "product_id": 67890,
  "name": "Cozy Winter Sweater",
  "description": "Soft and stylish sweater for cold days",
  "price": 59.99,
  "category": "Apparel",
  "brand": "Trendy Threads"
}

Now, update specific fields using:

POST /products/_doc/1/_update
{
  "doc": {
    "description": "Soft and stylish sweater for cold days. Available in multiple colors.",
    "category": "Apparel - Seasonal"
  }
}

After executing this update command, verify the changes by retrieving the document again:

GET /products/_doc/1

Deleting Documents and Indices

To delete a single document from the index:

DELETE /products/_doc/1

If you prefer to delete the entire index, execute:

DELETE /products/

Summary of Commands

Below is a consolidated list of essential Elasticsearch CRUD commands covered in this lesson:

GET _search
{
  "query": {
    "match_all": {}
  }
}

GET /_cluster/health

PUT /products

POST /products/_doc/1
{
  "product_id": 67890,
  "name": "Cozy Winter Sweater",
  "description": "Soft and stylish sweater for cold days",
  "price": 59.99,
  "category": "Apparel",
  "brand": "Trendy Threads"
}

GET /products/_doc/1

GET /products/_search
{
  "query": {
    "match": {
      "name": "sweater"
    }
  }
}

POST /products/_doc/1/_update
{
  "doc": {
    "description": "Soft and stylish sweater for cold days. Available in multiple colors.",
    "category": "Apparel - Seasonal"
  }
}

DELETE /products/_doc/1

DELETE /products/

Final Thoughts

Mastering these Elasticsearch CRUD commands is essential for effective data management and troubleshooting in your Elasticsearch environment. Experiment with these commands in Kibana’s DevTools to enhance your understanding and ensure smooth operations.

Happy querying!