Function score query in Elasticsearch - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this function score query?

Given the following Elasticsearch function score query, what is the resulting score for a document with field1 value 5 and field2 value 10?

Elasticsearch

{
  "query": {
    "function_score": {
      "query": { "match_all": {} },
      "functions": [
        {
          "field_value_factor": {
            "field": "field1",
            "factor": 2,
            "modifier": "sqrt"
          }
        },
        {
          "field_value_factor": {
            "field": "field2",
            "factor": 1.5
          }
        }
      ],
      "score_mode": "sum",
      "boost_mode": "replace"
    }
  }
}

A Score = sqrt(5) * 2 + 10 * 1.5 = 4.472 + 15 = 19.472

B Score = (sqrt(5) + 10) * 1.5 = (2.236 + 10) * 1.5 = 18.354

C Score = sqrt(5 * 2) + 10 * 1.5 = 3.162 + 15 = 18.162

D Score = sqrt(5) * 2 * 1.5 + 10 = 6.708 + 10 = 16.708

💡 Hint

Remember that the score_mode 'sum' adds the results of each function, and boost_mode 'replace' uses the function score as the final score.

The first function applies sqrt modifier to field1 (sqrt(5) ≈ 2.236) multiplied by factor 2 → 4.472. The second function multiplies field2 by 1.5 → 15. Sum is 4.472 + 15 = 19.472.

🧠 Conceptual

intermediate

Which score_mode combines function scores by multiplying them?

In an Elasticsearch function score query, which score_mode option multiplies the scores from each function together?

A "sum"

B "max"

C "avg"

D "multiply"

💡 Hint

Think about how scores combine when you want to increase or decrease the total score multiplicatively.

The score_mode "multiply" multiplies the scores from each function to produce the final score.

🔧 Debug

advanced

Why does this function score query cause a syntax error?

Identify the syntax error in this function score query snippet:

Elasticsearch

{
  "query": {
    "function_score": {
      "query": { "match_all": {} },
      "functions": [
        {
          "field_value_factor": {
            "field": "popularity",
            "factor": 1.2
          }
        },
        {
          "random_score": {
            "seed": 12345
          }
        }
      ],
      "score_mode": "sum",
      "boost_mode": "multiply"
    }
  }
}

A Invalid value for score_mode, should be 'multiply' not 'sum'

B Missing closing brace '}' at the end of the JSON

C random_score cannot be used inside functions array

D field_value_factor requires a 'modifier' field

💡 Hint

Check if all braces and brackets are properly closed.

The JSON is missing the closing brace '}' at the end, causing a syntax error.

📝 Syntax

advanced

Which option correctly uses a filter in a function score query?

Select the option that correctly applies a filter to a function inside a function score query.

A { "weight": 2, "filter": { "term": { "status": "active" } } }

B { "filter": { "term": { "status": "active" } }, "weight": 2 }

C { "weight": 2, "query": { "term": { "status": "active" } } }

D { "filter": { "match": { "status": "active" } }, "weight": 2 }

💡 Hint

The filter must be a sibling of weight inside the function object.

The correct syntax places 'weight' first and 'filter' as a sibling key with a valid term query. Option A is valid.

🚀 Application

expert

How many functions are applied in this function score query?

Given this function score query, how many scoring functions are applied?

Elasticsearch

{
  "query": {
    "function_score": {
      "query": { "match": { "title": "search" } },
      "functions": [
        { "weight": 3 },
        { "field_value_factor": { "field": "popularity", "factor": 1.1 } },
        { "random_score": {} },
        { "script_score": { "script": "doc['views'].value / 10" } }
      ],
      "score_mode": "avg",
      "boost_mode": "multiply"
    }
  }
}

A 3

B 2

C 4

D 1

💡 Hint

Count each object inside the 'functions' array.

There are 4 function objects inside the 'functions' array: weight, field_value_factor, random_score, and script_score.