First search query in Elasticsearch - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this Elasticsearch query?

Given the following Elasticsearch query, which option correctly describes what it returns?

Elasticsearch

{
  "query": {
    "match": {
      "message": "error"
    }
  }
}

A The query returns documents containing the word 'error' or 'warning'.

B The query returns all documents regardless of content.

C The query returns all documents containing the word 'error' in the 'message' field.

D The query returns documents containing the exact phrase 'error' only.

💡 Hint

Think about what the match query does in Elasticsearch.

The match query searches for documents that contain the word 'error' in the specified field. It does not require an exact phrase match and does not include other words like 'warning'.

🧠 Conceptual

intermediate

Which option correctly describes the purpose of the 'size' parameter in a search query?

In an Elasticsearch search query, what does the size parameter control?

A It controls the number of documents returned in the search results.

B It controls the maximum size of each document returned.

C It controls the number of shards to search.

D It controls the timeout duration for the query.

💡 Hint

Think about what you want to limit when you get search results.

The size parameter limits how many documents Elasticsearch returns in the search results. It does not affect document size or shards.

❓ Predict Output

advanced

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

Consider this query. What documents will it return?

Elasticsearch

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

A Documents where 'status' contains 'active' or 'age' is 30 or more.

B Documents where 'status' contains 'active' and 'age' is 30 or more.

C Documents where 'status' contains 'active' but 'age' is less than 30.

D Documents where 'age' is 30 or more regardless of 'status'.

💡 Hint

Remember how bool queries combine must and filter.

The bool query requires both conditions: the must clause matches documents with 'status' containing 'active', and the filter clause restricts to documents with 'age' greater or equal to 30.

🔧 Debug

advanced

What error does this Elasticsearch query produce?

Look at this query. What error will Elasticsearch return?

Elasticsearch

{
  "query": {
    "match": {
      "message": ["error", "failure"]
    }
  }
}

A The query runs successfully and matches documents containing either 'error' or 'failure'.

B The query returns no results because the list is empty.

C Elasticsearch throws a <code>type_error</code> because 'message' field is missing.

D Elasticsearch throws a <code>parsing_exception</code> because the 'match' query expects a string, not a list.

💡 Hint

Check the expected data type for the 'match' query value.

The match query expects a single string value. Passing a list causes a parsing_exception error.

🚀 Application

expert

How many documents are returned by this complex query?

Given this Elasticsearch query, how many documents will be returned if the index contains 100 documents where 40 have 'status' as 'active', 30 have 'age' ≥ 30, and 20 have both conditions?

Elasticsearch

{
  "query": {
    "bool": {
      "should": [
        { "match": { "status": "active" } },
        { "range": { "age": { "gte": 30 } } }
      ],
      "minimum_should_match": 1
    }
  }
}

A 50 documents

B 70 documents

C 100 documents

D 90 documents

💡 Hint

Use the formula for union of two sets: |A| + |B| - |A ∩ B|.

The query uses a bool query with should clauses and minimum_should_match: 1, which acts as an OR condition. It matches documents where 'status' contains 'active' (40 docs) OR 'age' ≥ 30 (30 docs), with 20 docs satisfying both. Total unique matching documents: 40 + 30 - 20 = 50.