Boolean and binary types in Elasticsearch - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this Elasticsearch query with a boolean filter?

Consider the following Elasticsearch query that filters documents based on a boolean field is_active. What documents will be returned?

Elasticsearch

{
  "query": {
    "bool": {
      "filter": [
        { "term": { "is_active": true } }
      ]
    }
  }
}

A All documents regardless of <code>is_active</code> value

B Only documents where the field <code>is_active</code> is true

C Only documents where the field <code>is_active</code> is false

D Documents where <code>is_active</code> field is missing

💡 Hint

Think about what the term filter does with boolean fields.

The term filter matches documents where the field exactly equals the given value. Here, it matches documents where is_active is true.

❓ Predict Output

intermediate

What is the result of indexing a binary field with base64 data?

You index a document with a binary field file_data containing base64 encoded string. What happens when you retrieve this field?

Elasticsearch

{
  "mappings": {
    "properties": {
      "file_data": { "type": "binary" }
    }
  }
}

A The field returns the original base64 encoded string exactly as indexed

B The field returns the decoded binary data as a string

C The field returns a JSON error because binary data is not supported

D The field is not stored and returns null

💡 Hint

Remember how Elasticsearch stores binary fields internally.

Binary fields store data as base64 encoded strings and return the same base64 string when retrieved.

🔧 Debug

advanced

Why does this boolean query return no results?

Given this query, why might it return zero documents even though some documents have is_verified set to false?

Elasticsearch

{
  "query": {
    "bool": {
      "must": [
        { "term": { "is_verified": false } }
      ]
    }
  }
}

A The <code>term</code> query does not match <code>false</code> because the field is mapped as a string, not boolean

B The <code>must</code> clause requires documents to have <code>is_verified</code> true, so false matches nothing

C The query syntax is invalid and causes an error

D The <code>term</code> query matches only <code>true</code> values by default

💡 Hint

Check the field mapping type and how term queries work with booleans.

If is_verified is mapped as a string, the term query with boolean false won't match any documents because the types differ.

📝 Syntax

advanced

Which option correctly defines a binary field in Elasticsearch mapping?

Choose the correct JSON snippet to define a binary field named image_data in an Elasticsearch index mapping.

A "image_data": { "type": "base64" }

B "image_data": { "type": "byte" }

C "image_data": { "type": "boolean" }

D "image_data": { "type": "binary" }

💡 Hint

Recall the exact type name Elasticsearch uses for binary data.

Elasticsearch uses binary as the type for base64 encoded binary data fields.

🚀 Application

expert

How many documents will match this boolean query with must_not clause?

Assume an index with 100 documents: 60 have is_active true, 40 have is_active false. What is the count of documents returned by this query?

{
  "query": {
    "bool": {
      "must_not": [
        { "term": { "is_active": true } }
      ]
    }
  }
}

A 100

B 60

C 40

D 0

💡 Hint

The must_not clause excludes documents matching the condition.

The query excludes documents where is_active is true, so only the 40 documents with is_active false remain.