Bool query in depth in Elasticsearch - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of a simple bool query with must and filter

What is the output of the following Elasticsearch bool query when searching documents with fields status and age?

Elasticsearch

{
  "query": {
    "bool": {
      "must": [
        { "match": { "status": "active" } }
      ],
      "filter": [
        { "range": { "age": { "gte": 30 } } }
      ]
    }
  }
}

A Documents where status is 'active' and age is 30 or more

B Documents where status is 'active' but age is less than 30

C Documents where status is 'active' or age is 30 or more

D Documents where age is 30 or more only

💡 Hint

Remember that must means all conditions must match, and filter applies additional filtering without affecting scoring.

The must clause requires documents to match the status: active. The filter clause restricts results to those with age greater or equal to 30. Both conditions must be true for a document to be returned.

❓ Predict Output

intermediate

Effect of must_not in bool query

Given this bool query, what documents will it return?

Elasticsearch

{
  "query": {
    "bool": {
      "must": [
        { "match": { "category": "books" } }
      ],
      "must_not": [
        { "term": { "author": "John Doe" } }
      ]
    }
  }
}

A Documents not in category 'books' and not authored by 'John Doe'

B Documents authored by 'John Doe' in any category

C Documents in category 'books' authored by 'John Doe' only

D Documents in category 'books' excluding those authored by 'John Doe'

💡 Hint

The must_not clause excludes documents matching its condition.

The must clause requires documents to be in the 'books' category. The must_not clause excludes documents where the author is 'John Doe'. So the result is books not written by John Doe.

🔧 Debug

advanced

Identify the error in this bool query

What error will this Elasticsearch bool query cause?

Elasticsearch

{
  "query": {
    "bool": {
      "must": {
        "match": { "title": "Elasticsearch" }
      },
      "filter": {
        "range": { "date": { "gte": "2023-01-01" } }
      },
      "must_not": [
        { "term": { "status": "archived" } }
      ]
    }
  }
}

A RuntimeError: 'range' query requires a 'lte' parameter

B No error, query runs successfully

C SyntaxError: 'must' and 'filter' must be arrays, not objects

D TypeError: 'must_not' must be an object, not an array

💡 Hint

Check the expected data types for must and filter clauses.

In Elasticsearch bool queries, must and filter expect arrays of queries, not single objects. Using objects instead causes a syntax error.

🧠 Conceptual

advanced

Understanding scoring in bool queries

Which clause in a bool query affects the relevance score of documents?

A <code>must</code> and <code>should</code> clauses affect scoring; <code>filter</code> does not

B <code>filter</code> clause affects scoring; <code>must</code> does not

C Only <code>must_not</code> affects scoring

D All clauses affect scoring equally

💡 Hint

Think about which clauses contribute to relevance calculation.

The must and should clauses contribute to the relevance score. The filter clause is used for filtering and does not affect scoring. The must_not clause excludes documents and does not affect scoring.

🚀 Application

expert

Compose a bool query for complex conditions

You want to find documents where:
- The field tags contains 'python' or 'elasticsearch'
- The field published is true
- The field views is greater than 1000
- The field author is NOT 'anonymous'

Which bool query correctly implements these conditions?

A

{
  "query": {
    "bool": {
      "should": [
        { "terms": { "tags": ["python", "elasticsearch"] } }
      ],
      "must": [
        { "term": { "published": true } },
        { "range": { "views": { "gt": 1000 } } }
      ],
      "must_not": [
        { "term": { "author": "anonymous" } }
      ]
    }
  }
}

B

{
  "query": {
    "bool": {
      "filter": [
        { "terms": { "tags": ["python", "elasticsearch"] } },
        { "term": { "published": true } },
        { "range": { "views": { "gt": 1000 } } }
      ],
      "must_not": [
        { "term": { "author": "anonymous" } }
      ]
    }
  }
}

C

{
  "query": {
    "bool": {
      "should": [
        { "term": { "tags": "python" } },
        { "term": { "tags": "elasticsearch" } }
      ],
      "filter": [
        { "term": { "published": true } },
        { "range": { "views": { "gt": 1000 } } }
      ],
      "must_not": [
        { "term": { "author": "anonymous" } }
      ]
    }
  }
}

D

{
  "query": {
    "bool": {
      "must": [
        { "term": { "tags": "python" } },
        { "term": { "tags": "elasticsearch" } },
        { "term": { "published": true } },
        { "range": { "views": { "gt": 1000 } } }
      ],
      "must_not": [
        { "term": { "author": "anonymous" } }
      ]
    }
  }
}

💡 Hint

Use terms query within filter or must for required OR conditions, must_not to exclude.

The filter clauses require documents to match at least one of 'python' or 'elasticsearch' in tags (using terms query), have published set to true, and views greater than 1000. The must_not excludes documents where author is 'anonymous'.