Dis max query in Elasticsearch - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the score behavior of this dis_max query?

Given the following Elasticsearch dis_max query, what will be the _score of a document that matches both clauses equally with a tie_breaker of 0.3?

Elasticsearch

{
  "query": {
    "dis_max": {
      "tie_breaker": 0.3,
      "queries": [
        { "match": { "title": "apple" } },
        { "match": { "description": "apple" } }
      ]
    }
  }
}

A The score is the sum of both match scores without any multiplier.

B The score is the average of the two match scores.

C The score is the maximum score of the two matches plus 0.3 times the other score.

D The score is only the maximum score of the two matches, ignoring the tie_breaker.

💡 Hint

Remember that dis_max uses the highest score plus a fraction of the others based on tie_breaker.

The dis_max query returns the maximum score from its subqueries plus a fraction (tie_breaker) of the other scores. This helps boost documents matching multiple queries without simply summing all scores.

🧠 Conceptual

intermediate

Which use case best fits a dis_max query?

Which scenario is the best reason to use a dis_max query in Elasticsearch?

A You want to find documents matching any of several queries but prefer the highest scoring match with some bonus for others.

B You want to boost documents that match all queries by multiplying their scores.

C You want to filter documents strictly matching all queries.

D You want to combine multiple queries and sum all their scores equally.

💡 Hint

Dis max is about picking the best match with some influence from others.

Dis max is designed to pick the highest scoring query match and add a fraction of other matches, useful when you want to prefer the best match but still reward multiple matches.

🔧 Debug

advanced

Why does this dis_max query ignore the tie_breaker?

Consider this dis_max query: { "query": { "dis_max": { "tie_breaker": 0.5, "queries": [ { "match": { "field1": "test" } }, { "match": { "field2": "test" } } ] } } } Why might the tie_breaker have no effect on the scoring?

A Because only one of the queries matches the document, so no tie breaker is applied.

B Because the tie_breaker value must be between 0 and 1 exclusive, and 0.5 is invalid.

C Because dis_max requires a minimum_should_match parameter to apply tie_breaker.

D Because the queries are inside a bool filter, which disables scoring.

💡 Hint

Tie breaker only affects when multiple queries match.

The tie_breaker only adds a fraction of the scores from other matching queries. If only one query matches, the tie_breaker has no effect.

📝 Syntax

advanced

Identify the syntax error in this dis_max query

Which option contains a syntax error in the dis_max query?

Elasticsearch

{
  "query": {
    "dis_max": {
      "tie_breaker": 0.2,
      "queries": [
        { "match": { "field": "value1" } },
        { "match": { "field": "value2" } }
      ]
    }
  }
}

A { "dis_max": { "tieBreaker": 0.2, "queries": [ { "match": { "field": "value1" } }, { "match": { "field": "value2" } } ] } }

B { "dis_max": { "tie_breaker": 0.2, "query": [ { "match": { "field": "value1" } }, { "match": { "field": "value2" } } ] } }

C { "dis_max": { "tie_breaker": 0.2, "queries": [ { "match": { "field": "value1" } }, { "match": { "field": "value2" } } ] } }

D } } ] } } "2eulav" :"dleif" { :"hctam" { ,} } "1eulav" :"dleif" { :"hctam" { [ :"seireuq" ,2.0 :"rekaerb_eit" { :"xam_sid" {

💡 Hint

Check the key name for the list of queries inside dis_max.

The correct key for the list of queries inside dis_max is "queries" not "query". Using "query" causes a syntax error.

🚀 Application

expert

How to combine dis_max with boosting for best relevance?

You want to search documents matching either 'title' or 'content' fields. You want the best match to score highest but also boost matches in 'title' by 2x. Which query achieves this?

A

{
  "dis_max": {
    "tie_breaker": 0.1,
    "queries": [
      { "match": { "title": "search" } },
      { "match": { "content": { "query": "search", "boost": 2 } } }
    ]
  }
}

B

{
  "bool": {
    "should": [
      { "match": { "title": { "query": "search", "boost": 2 } } },
      { "match": { "content": "search" } }
    ]
  }
}

C

{
  "function_score": {
    "query": {
      "dis_max": {
        "tie_breaker": 0.1,
        "queries": [
          { "match": { "title": "search" } },
          { "match": { "content": "search" } }
        ]
      }
    },
    "boost": 2
  }
}

D

{
  "dis_max": {
    "tie_breaker": 0.1,
    "queries": [
      { "match": { "title": { "query": "search", "boost": 2 } } },
      { "match": { "content": "search" } }
    ]
  }
}

💡 Hint

Boost inside the match query affects that field's score before dis_max combines them.

Boosting the 'title' match inside the dis_max queries increases its score before dis_max picks the max plus tie breaker. This way, matches in 'title' get higher priority.

Practice

1. What is the main purpose of the dis_max query in Elasticsearch?

easy

A. To select the highest score from multiple queries to find the best match

B. To combine all scores from multiple queries by summing them

C. To filter documents based on a single exact match

D. To sort documents alphabetically by a field

Solution

1. Step 1: Understand the dis_max query behavior

   The dis_max query evaluates multiple queries and picks the highest score among them for each document.

2. Step 2: Compare with other scoring methods

   Unlike sum or filter queries, dis_max focuses on the best single match score, not combined or filtered results.

3. Final Answer:

   To select the highest score from multiple queries to find the best match -> Option A

4. Quick Check:

   dis_max picks highest score = A [OK]

Hint: Remember: dis_max picks the best single score, not sums [OK]

Common Mistakes:

• Thinking dis_max sums scores from all queries
• Confusing dis_max with filter queries
• Assuming dis_max sorts documents alphabetically

2. Which of the following is the correct syntax to use a dis_max query with two match queries in Elasticsearch?

easy

A. {\"dis_max\": {\"queries\": {\"match\": {\"field1\": \"value1\"}, \"match\": {\"field2\": \"value2\"}}}}

B. {\"dis_max\": [{\"match\": {\"field1\": \"value1\"}}, {\"match\": {\"field2\": \"value2\"}}]}

C. {\"dis_max\": {\"queries\": [{\"match\": {\"field1\": \"value1\"}}, {\"match\": {\"field2\": \"value2\"}}]}}

D. {\"dis_max\": {\"query\": [{\"match\": {\"field1\": \"value1\"}}, {\"match\": {\"field2\": \"value2\"}}]}}

Solution

1. Step 1: Check the dis_max query structure

   The dis_max query requires a queries array containing individual query objects.

2. Step 2: Validate the JSON syntax

   {\"dis_max\": {\"queries\": [{\"match\": {\"field1\": \"value1\"}}, {\"match\": {\"field2\": \"value2\"}}]}} correctly uses queries as an array with two match queries inside separate objects.

3. Final Answer:

   {"dis_max": {"queries": [{"match": {"field1": "value1"}}, {"match": {"field2": "value2"}}]}} -> Option C

4. Quick Check:

   dis_max uses queries array = D [OK]

Hint: dis_max needs a 'queries' array, not 'query' or object [OK]

Common Mistakes:

• Using 'query' instead of 'queries' key
• Passing queries as an object instead of an array
• Omitting the array brackets around queries

3. Given this Elasticsearch query snippet using dis_max with tie_breaker set to 0.3:

{
  "dis_max": {
    "queries": [
      { "match": { "title": "apple" } },
      { "match": { "description": "apple" } }
    ],
    "tie_breaker": 0.3
  }
}

What effect does the tie_breaker parameter have on the scoring?

medium

A. It adds 30% of the scores from non-highest matching queries to the final score

B. It multiplies the highest score by 0.3

C. It ignores all but the highest scoring query

D. It subtracts 0.3 from the highest score

Solution

1. Step 1: Understand tie_breaker in dis_max

   The tie_breaker adds a fraction of the scores from other matching queries to the highest score.

2. Step 2: Apply the 0.3 value meaning

   With tie_breaker 0.3, 30% of the other query scores are added to the highest score, boosting documents matching multiple queries.

3. Final Answer:

   It adds 30% of the scores from non-highest matching queries to the final score -> Option A

4. Quick Check:

   tie_breaker 0.3 adds 30% other scores = C [OK]

Hint: tie_breaker adds fraction of other scores to highest score [OK]

Common Mistakes:

• Thinking tie_breaker multiplies highest score directly
• Assuming tie_breaker ignores other queries
• Believing tie_breaker subtracts from scores

4. You wrote this dis_max query but it returns an error:

{
  "dis_max": {
    "queries": {
      { "match": { "field1": "value1" } },
      { "match": { "field2": "value2" } }
    }
  }
}

What is the error and how to fix it?

medium

A. The dis_max query requires a boost parameter

B. The queries value should be an array, not an object; replace curly braces with square brackets

C. The match queries must be inside a 'query' key, not 'queries'

D. The field names must be strings without quotes

Solution

1. Step 1: Identify the queries structure error

   The queries key must hold an array of query objects, but curly braces {} were used, making it an object.

2. Step 2: Correct the syntax

   Replace the curly braces around the queries with square brackets [] to form a valid array.

3. Final Answer:

   The queries value should be an array, not an object; replace curly braces with square brackets -> Option B

4. Quick Check:

   queries must be array [] not object {} = A [OK]

Hint: Use [] for queries array, not {} [OK]

Common Mistakes:

• Using curly braces instead of square brackets for queries
• Adding unnecessary boost parameter causing errors
• Removing quotes from field names

5. You want to boost the importance of a dis_max query compared to other queries in your Elasticsearch search. Which is the correct way to apply a boost to the entire dis_max query?

hard

A. { "dis_max": { "boost": 2.0, "tie_breaker": 0.5 } }

B. { "dis_max": { "queries": [...], "boost": "high" } }

C. { "dis_max": { "queries": [...], "tie_breaker": 2.0 } }

D. { "dis_max": { "queries": [...], "boost": 2.0 } }

Solution

1. Step 1: Understand boost usage in dis_max

   The boost parameter is applied at the dis_max query level to increase its overall importance.

2. Step 2: Validate correct boost syntax

   Boost must be a numeric value; { "dis_max": { "queries": [...], "boost": 2.0 } } correctly places boost: 2.0 inside dis_max alongside queries.

3. Final Answer:

   { "dis_max": { "queries": [...], "boost": 2.0 } } -> Option D

4. Quick Check:

   Boost is numeric and inside dis_max = B [OK]

Hint: Put numeric boost inside dis_max alongside queries [OK]

Common Mistakes:

• Using non-numeric boost values like strings
• Placing boost outside dis_max query
• Confusing tie_breaker with boost