Constant score query in Elasticsearch - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this constant_score query?

Given the following Elasticsearch query, what is the score of each document matching the filter?

Elasticsearch

{
  "query": {
    "constant_score": {
      "filter": {
        "term": { "status": "active" }
      },
      "boost": 5
    }
  }
}

A Each matching document has a score of 5

B Each matching document has a score equal to the term frequency of "active"

C Each matching document has a score of 1

D Each matching document has a score of 0

💡 Hint

Remember that constant_score sets the score to the boost value for all matching documents.

The constant_score query wraps a filter and assigns a fixed score (boost) to all documents matching the filter, ignoring relevance scoring.

🧠 Conceptual

intermediate

Why use a constant_score query instead of a match query?

Which of the following is the main reason to use a constant_score query?

A To perform full-text search with relevance scoring

B To sort documents by their field values

C To assign the same score to all matching documents regardless of relevance

D To update documents in the index

💡 Hint

Think about when you want to ignore relevance and just filter with a fixed score.

Constant_score queries are used when you want to filter documents and assign them a fixed score, ignoring the usual relevance calculations.

🔧 Debug

advanced

Identify the error in this constant_score query

What error will this query produce?

Elasticsearch

{
  "query": {
    "constant_score": {
      "filter": {
        "match": { "title": "Elasticsearch" }
      },
      "boost": "high"
    }
  }
}

A SyntaxError: missing comma after filter

B TypeError: boost must be a number, not a string

C No error, query runs successfully

D RuntimeError: match query not allowed inside constant_score

💡 Hint

Check the type of the boost value.

The boost parameter must be a numeric value. Using a string like "high" causes a type error.

📝 Syntax

advanced

Which option is the correct syntax for a constant_score query with a range filter?

Select the valid constant_score query that filters documents with age greater than 30 and assigns a boost of 3.

A { "query": { "constant_score": { "filter": { "range": { "age": { "greater_than": 30 } } }, "boost": 3 } } }

B { "query": { "constant_score": { "filter": { "range": { "age": { "min": 30 } } }, "boost": 3 } } }

C { "query": { "constant_score": { "filter": { "range": { "age": { "gte": 30 } } }, "boost": 3 } } }

D { "query": { "constant_score": { "filter": { "range": { "age": { "gt": 30 } } }, "boost": 3 } } }

💡 Hint

Check the correct range operator for greater than in Elasticsearch.

Elasticsearch range query uses 'gt' for greater than (strictly > 30) and 'gte' for greater than or equal to (>= 30). The question specifies 'greater than 30', so 'gt' (option D) is correct. Option D uses invalid 'min', option D uses invalid 'greater_than', option D uses 'gte' which includes 30.

🚀 Application

expert

How many documents will be scored with boost 10 in this query?

Assume the index has 1000 documents. 200 have field "category" equal to "books". What is the number of documents that will have a score of 10 after running this query?

Elasticsearch

{
  "query": {
    "constant_score": {
      "filter": {
        "term": { "category": "books" }
      },
      "boost": 10
    }
  }
}

A 200

B 1000

C 0

D 800

💡 Hint

Only documents matching the filter get the boost score.

Only the 200 documents with category 'books' match the filter and get the constant score of 10. Others are excluded.