Runtime fields in Elasticsearch - Mini Project: Build & Apply

Using Runtime Fields in Elasticsearch

📖 Scenario: You have a collection of products indexed in Elasticsearch. Each product has a price and quantity field. You want to calculate the total_value of each product (price multiplied by quantity) on the fly without changing the original data.

🎯 Goal: Create a runtime field called total_value that calculates the product of price and quantity for each document. Then, query the index to show the name and total_value for each product.

📋 What You'll Learn

Create an index mapping with fields name (keyword), price (double), and quantity (integer).

Add a runtime field total_value that multiplies price and quantity.

Index at least 3 product documents with exact values.

Query the index to return name and total_value fields.

💡 Why This Matters

🌍 Real World

Runtime fields help you add new calculated data to your Elasticsearch queries without reindexing your data. This is useful when you want quick insights or temporary calculations.

💼 Career

Many jobs working with Elasticsearch require knowledge of runtime fields to optimize queries and add dynamic data without downtime or heavy reindexing.

1

Create the index with product data

Create an index called products with the following documents exactly: {"name": "Pen", "price": 1.5, "quantity": 10}, {"name": "Notebook", "price": 3.0, "quantity": 5}, and {"name": "Eraser", "price": 0.5, "quantity": 20}. Use the _bulk API to add these documents.

Elasticsearch

# Use the _bulk API to index the 3 products
# Your code here

Need a hint?

Use the _bulk API with { "index": {} } lines before each document.

2

Add a runtime field for total value

Update the products index mapping to add a runtime field called total_value of type double. This field should calculate doc['price'].value * doc['quantity'].value.

Elasticsearch

POST /products/_bulk
{ "index": {} }
{ "name": "Pen", "price": 1.5, "quantity": 10 }
{ "index": {} }
{ "name": "Notebook", "price": 3.0, "quantity": 5 }
{ "index": {} }
{ "name": "Eraser", "price": 0.5, "quantity": 20 }

# Add runtime field mapping below
# Your code here

Need a hint?

Use the PUT /products/_mapping API with a runtime field named total_value and a script that multiplies price and quantity.

3

Query products with runtime field

Write a search query on the products index that returns the name and the runtime field total_value for each product. Use _source to include name and runtime_mappings to include total_value.

Elasticsearch

POST /products/_bulk
{ "index": {} }
{ "name": "Pen", "price": 1.5, "quantity": 10 }
{ "index": {} }
{ "name": "Notebook", "price": 3.0, "quantity": 5 }
{ "index": {} }
{ "name": "Eraser", "price": 0.5, "quantity": 20 }

PUT /products/_mapping
{
  "runtime": {
    "total_value": {
      "type": "double",
      "script": {
        "source": "emit(doc['price'].value * doc['quantity'].value)"
      }
    }
  }
}

# Write the search query below
# Your code here

Need a hint?

Use _source to get name, add runtime_mappings for total_value, and request fields to show total_value.

4

Display the product names and total values

Print the name and total_value for each product from the search results. Format each line as: Product: <name>, Total Value: <total_value>.

Elasticsearch

POST /products/_bulk
{ "index": {} }
{ "name": "Pen", "price": 1.5, "quantity": 10 }
{ "index": {} }
{ "name": "Notebook", "price": 3.0, "quantity": 5 }
{ "index": {} }
{ "name": "Eraser", "price": 0.5, "quantity": 20 }

PUT /products/_mapping
{
  "runtime": {
    "total_value": {
      "type": "double",
      "script": {
        "source": "emit(doc['price'].value * doc['quantity'].value)"
      }
    }
  }
}

GET /products/_search
{
  "_source": ["name"],
  "runtime_mappings": {
    "total_value": {
      "type": "double",
      "script": {
        "source": "emit(doc['price'].value * doc['quantity'].value)"
      }
    }
  },
  "fields": ["total_value"]
}

# Print each product's name and total_value in the format:
# Product: , Total Value: 
# Your code here

Need a hint?

Print each product's name and total_value exactly as shown.