Pagination (from/size) in Elasticsearch - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this Elasticsearch query pagination?

Given an Elasticsearch index with 10 documents numbered 1 to 10, what documents will be returned by this query?

Elasticsearch

{
  "from": 3,
  "size": 4,
  "query": {
    "match_all": {}
  }
}

A [3, 4, 5, 6]

B [4, 5, 6, 7]

C [1, 2, 3, 4]

D [7, 8, 9, 10]

💡 Hint

Remember that 'from' is zero-based and skips that many documents before returning results.

The 'from' parameter skips the first 3 documents (1, 2, 3). Then 'size' 4 returns the next 4 documents: 4, 5, 6, 7.

❓ Predict Output

intermediate

What happens if you set 'from' to 0 and 'size' to 0 in Elasticsearch?

Consider this query. What will be the result?

Elasticsearch

{
  "from": 0,
  "size": 0,
  "query": {
    "match_all": {}
  }
}

A All documents returned

B Returns one document only

C Syntax error, query fails

D No documents returned, only metadata like total hits

💡 Hint

Size 0 means no hits are returned, but metadata is still included.

Setting 'size' to 0 returns no hits but still returns metadata such as total hits count.

🔧 Debug

advanced

Why does this pagination query return an error?

This query causes an error. Identify the cause.

Elasticsearch

{
  "from": -5,
  "size": 10,
  "query": {
    "match_all": {}
  }
}

A 'from' cannot be negative, causes a validation error

B 'size' cannot be greater than 5

C Missing 'sort' field causes error

D Query syntax is invalid due to missing brackets

💡 Hint

Check the allowed range for 'from' parameter.

The 'from' parameter must be zero or positive. Negative values cause a validation error.

🧠 Conceptual

advanced

What is a limitation of using 'from' and 'size' for deep pagination in Elasticsearch?

Why is using large 'from' values with 'size' problematic in Elasticsearch?

A Performance degrades because Elasticsearch must skip many documents internally

B It causes syntax errors in the query

C It returns duplicate documents

D It limits the total number of documents returned to 1000

💡 Hint

Think about how Elasticsearch processes skipped documents.

Using large 'from' values makes Elasticsearch skip many documents internally, which slows down queries.

❓ Predict Output

expert

What is the output of this paginated query with sorting?

Given documents with field 'age' values [30, 20, 40, 10, 50], what documents are returned by this query?

Elasticsearch

{
  "from": 1,
  "size": 2,
  "sort": [{"age": "asc"}],
  "query": {
    "match_all": {}
  }
}

A [30, 40]

B [10, 20]

C [20, 30]

D [40, 50]

💡 Hint

Sort ascending by age, then skip 1 document and take 2.

Sorted ascending by age: [10, 20, 30, 40, 50]. 'from':1 skips 10, next two are 20 and 30.