Multi-match query in Elasticsearch - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a multi-match query in Elasticsearch?

A multi-match query lets you search for a text across multiple fields in your documents at once. It helps find matches in any of the specified fields.

beginner

Which parameter specifies the fields to search in a multi-match query?

The fields parameter lists the fields where Elasticsearch will look for the search text.

intermediate

What does the type option in a multi-match query control?

The type option controls how the query matches text across fields, like best_fields (default), most_fields, cross_fields, phrase, or phrase_prefix.

intermediate

How does the operator parameter affect a multi-match query?

The operator parameter decides if all words must match (and) or if any word can match (or) in the search text.

beginner

Give an example of a simple multi-match query searching for 'apple' in fields 'title' and 'description'.

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

What does a multi-match query do in Elasticsearch?

A Searches for a text in multiple fields at once

B Updates multiple documents simultaneously

C Deletes multiple fields from documents

D Indexes multiple documents in one request

A multi-match query searches for the given text across multiple fields in the documents.

Which parameter lists the fields to search in a multi-match query?

A operator

B fields

C query

D type

The 'fields' parameter specifies which fields to search in.

What is the default type for a multi-match query?

A most_fields

B phrase

C cross_fields

D best_fields

The default type is 'best_fields', which finds the single best matching field.

If you want all words in the query to match, which operator should you use?

A and

B exists

C not

D or

The 'and' operator requires all words to match in the fields.

Which multi-match type treats multiple fields as one combined field for matching?

A best_fields

B most_fields

C cross_fields

D phrase

The 'cross_fields' type treats fields as one combined field to match terms.

Explain how a multi-match query works and when you would use it.

Think about searching a book by title and author at the same time.

Describe the difference between 'best_fields' and 'cross_fields' types in a multi-match query.

Imagine searching for a phrase split across two fields.

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