Multi-match query in Elasticsearch - Mini Project: Build & Apply

Multi-match Query in Elasticsearch

📖 Scenario: You are building a search feature for an online bookstore. Users want to search for books by matching their search words against multiple fields like title, author, and description.

🎯 Goal: Create an Elasticsearch multi-match query that searches for the word "adventure" in the title, author, and description fields.

📋 What You'll Learn

Create a JSON object called query with a multi_match key

Set the query value inside multi_match to the exact string "adventure"

Set the fields inside multi_match to the exact list ["title", "author", "description"]

Print the complete JSON query object

💡 Why This Matters

🌍 Real World

Multi-match queries are used in search engines to find matches across several fields, improving search relevance for users.

💼 Career

Knowing how to build multi-match queries is essential for roles involving Elasticsearch, such as backend developers, data engineers, and search specialists.

1

Create the base JSON query object

Create a JSON object called query with a multi_match key that contains an empty object.

Elasticsearch

query = {
    "multi_match": {
        
    }
}
# Your code here

Hint

Start by creating a dictionary named query with a key multi_match that holds an empty dictionary.

2

Add the search term to the multi_match query

Inside the multi_match object in query, add the key query with the exact value "adventure".

Elasticsearch

query = {
    "multi_match": {
        # Add the query key with value "adventure" here
    }
}

Hint

Add the key query inside multi_match and set it to the string "adventure".

3

Add the fields list to search in

Inside the multi_match object in query, add the key fields with the exact list value ["title", "author", "description"].

Elasticsearch

query = {
    "multi_match": {
        "query": "adventure",
        # Add the fields key with the list ["title", "author", "description"] here
    }
}

Hint

Add the key fields inside multi_match and set it to the list ["title", "author", "description"].

4

Print the complete query JSON

Write a print(query) statement to display the complete multi-match query JSON object.

Elasticsearch

query = {
    "multi_match": {
        "query": "adventure",
        "fields": ["title", "author", "description"]
    }
}
# Print the query object below

Hint

Use print(query) to show the full JSON query object.

Practice

1. What is the main purpose of a multi-match query in Elasticsearch?

easy

A. To search multiple fields with a single query

B. To update multiple documents at once

C. To delete multiple indexes simultaneously

D. To create multiple indexes in one request

Solution

1. Step 1: Understand the multi-match query concept

   A multi-match query allows searching across several fields in one query, making it easier to find matches in different parts of documents.

2. Step 2: Compare with other options

   The other options describe operations like creating indexes, updating documents, or deleting indexes, which are not the purpose of multi-match queries.

3. Final Answer:

   To search multiple fields with a single query -> Option A

4. Quick Check:

   Multi-match = search multiple fields [OK]

Hint: Multi-match searches many fields at once [OK]

Common Mistakes:

• Confusing multi-match with update or delete operations
• Thinking it creates or deletes indexes
• Assuming it searches only one field

2. Which of the following is the correct syntax to perform a multi-match query searching for the word "apple" in fields "title" and "description"?

easy

A. { "multi_match": { "query": "apple", "fields": ["title", "description"] } }

B. { "match": { "query": "apple", "fields": ["title", "description"] } }

C. { "multi_match": { "fields": ["title", "description"] } }

D. { "multi_match": { "query": "apple" } }

Solution

1. Step 1: Identify required keys in multi-match query

   A multi-match query requires a "query" key with the search term and a "fields" key listing the fields to search.

2. Step 2: Check each option for correct syntax

   { "multi_match": { "query": "apple", "fields": ["title", "description"] } } correctly includes both "query" and "fields" keys. { "match": { "query": "apple", "fields": ["title", "description"] } } uses "match" instead of "multi_match". { "multi_match": { "fields": ["title", "description"] } } misses the "query" key. { "multi_match": { "query": "apple" } } misses the "fields" key.

3. Final Answer:

   { "multi_match": { "query": "apple", "fields": ["title", "description"] } } -> Option A

4. Quick Check:

   multi_match needs query and fields [OK]

Hint: multi_match needs both query and fields keys [OK]

Common Mistakes:

• Using 'match' instead of 'multi_match'
• Omitting the 'query' key
• Omitting the 'fields' key

3. Given this multi-match query, what will be the effect?

{
  "multi_match": {
    "query": "quick fox",
    "fields": ["title", "content"],
    "type": "phrase"
  }
}

medium

A. Searches only the title field for the phrase "quick fox"

B. Searches for documents containing "quick" or "fox" anywhere in title or content

C. Searches for documents where "quick fox" appears as a phrase in either title or content

D. Searches for documents with exact match "quick fox" in all fields

Solution

1. Step 1: Understand the 'type' parameter in multi-match

   The "type": "phrase" option makes the query look for the exact phrase "quick fox" in the specified fields.

2. Step 2: Check fields and matching behavior

   The fields are "title" and "content", so the phrase must appear in either field, not necessarily both.

3. Final Answer:

   Searches for documents where "quick fox" appears as a phrase in either title or content -> Option C

4. Quick Check:

   type phrase = exact phrase match in fields [OK]

Hint: type phrase means exact phrase search [OK]

Common Mistakes:

• Thinking it searches for words separately (not phrase)
• Assuming it searches only one field
• Believing it requires phrase in all fields

4. Identify the error in this multi-match query:

{
  "multi_match": {
    "query": "data",
    "fields": "title, description"
  }
}

medium

A. "query" should be an array of words

B. "fields" should be an array, not a string

C. "multi_match" should be "match"

D. "fields" should be omitted for multi-match

Solution

1. Step 1: Check the type of "fields" value

   The "fields" key must be an array of field names, not a single string with commas.

2. Step 2: Validate other keys

   The "query" key is correctly a string. "multi_match" is the correct query type. "fields" should not be omitted.

3. Final Answer:

   "fields" should be an array, not a string -> Option B

4. Quick Check:

   fields must be array, not comma string [OK]

Hint: Fields must be an array, not a comma string [OK]

Common Mistakes:

• Passing fields as a comma-separated string
• Changing multi_match to match incorrectly
• Thinking query must be an array

5. You want to search for the term "coffee" giving higher importance to the "title" field than "description" and "tags" fields. Which multi-match query correctly applies this weighting?

hard

A. { "multi_match": { "query": "coffee", "fields": ["title", "description", "tags"], "boost": 3 } }

B. { "multi_match": { "query": "coffee", "fields": ["title", "description^3", "tags"] } }

C. { "multi_match": { "query": "coffee", "fields": ["title", "description", "tags"], "type": "boost" } }

D. { "multi_match": { "query": "coffee", "fields": ["title^3", "description", "tags"] } }

Solution

1. Step 1: Understand field boosting syntax

   To give more importance to a field, add a caret (^) and a boost number after the field name, e.g., "title^3".

2. Step 2: Check each option for correct boosting

   { "multi_match": { "query": "coffee", "fields": ["title^3", "description", "tags"] } } boosts "title" by 3, others default. { "multi_match": { "query": "coffee", "fields": ["title", "description^3", "tags"] } } boosts "description" incorrectly. { "multi_match": { "query": "coffee", "fields": ["title", "description", "tags"], "boost": 3 } } tries to boost all fields equally with "boost" key, which is invalid here. { "multi_match": { "query": "coffee", "fields": ["title", "description", "tags"], "type": "boost" } } uses an invalid "type" value.

3. Final Answer:

   { "multi_match": { "query": "coffee", "fields": ["title^3", "description", "tags"] } } -> Option D

4. Quick Check:

   Use ^number to boost fields [OK]

Hint: Boost fields with ^number after field name [OK]

Common Mistakes:

• Boosting wrong field
• Using 'boost' key incorrectly
• Setting invalid 'type' value