Sorting results in Elasticsearch - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output order of this Elasticsearch sort query?

Given the following Elasticsearch query, what is the order of the returned documents by their price field?

Elasticsearch

{
  "query": { "match_all": {} },
  "sort": [
    { "price": { "order": "asc" } }
  ]
}

A Documents sorted from lowest to highest price

B Documents sorted from highest to lowest price

C Documents sorted alphabetically by price field

D Documents returned in random order

💡 Hint

Look at the order value inside the sort array.

The sort clause with order": "asc" sorts documents from the lowest to the highest value of the price field.

❓ Predict Output

intermediate

What happens if you sort by a non-existent field in Elasticsearch?

Consider this Elasticsearch query that sorts by a field rating which does not exist in any document. What will be the result?

Elasticsearch

{
  "query": { "match_all": {} },
  "sort": [
    { "rating": { "order": "desc" } }
  ]
}

A Elasticsearch throws an error about missing field

B Documents are returned in original order because <code>rating</code> is missing

C Documents are sorted with missing <code>rating</code> treated as highest values

D Documents are sorted with missing <code>rating</code> treated as lowest values

💡 Hint

By default ('_last'), missing fields are treated as highest values.

Elasticsearch's default for missing sort values is '_last', treating them as higher than any existing value. For desc order, documents missing rating appear last.

🔧 Debug

advanced

Why does this Elasticsearch sort query cause an error?

Look at this Elasticsearch query that tries to sort by date descending but causes an error. What is the cause?

Elasticsearch

{
  "query": { "match_all": {} },
  "sort": [
    { "date": "desc" }
  ]
}

A The <code>desc</code> value must be uppercase

B The <code>date</code> field does not exist in the index

C Sorting by date requires a script, not a field name

D The sort syntax is invalid; the order must be inside an object with key <code>order</code>

💡 Hint

Check the correct syntax for sorting by a field with order.

The correct syntax for sorting by a field with order is to use an object with the key order. Writing { "date": "desc" } is invalid. It should be { "date": { "order": "desc" } }.

🧠 Conceptual

advanced

How does Elasticsearch handle sorting by multiple fields?

Given this sort clause, how does Elasticsearch order the documents?

{
  "sort": [
    { "price": { "order": "asc" } },
    { "rating": { "order": "desc" } }
  ]
}

A Documents are sorted first by <code>price</code> ascending, then by <code>rating</code> descending for ties

B Documents are sorted by <code>rating</code> descending, then by <code>price</code> ascending

C Documents are sorted randomly ignoring the fields

D Documents are sorted by the sum of <code>price</code> and <code>rating</code>

💡 Hint

Think about the order of fields in the sort array.

Elasticsearch sorts documents by the first field in the sort array. If there are ties, it uses the next field to break ties, and so on. Here, it sorts by price ascending first, then by rating descending.

❓ Predict Output

expert

What is the output of this Elasticsearch sort with nested field and missing values?

Consider documents with a nested field author.name. This query sorts by author.name.keyword ascending, treating missing values as last. What is the order of documents?

Elasticsearch

{
  "query": { "match_all": {} },
  "sort": [
    {
      "author.name.keyword": {
        "order": "asc",
        "missing": "_last"
      }
    }
  ]
}

A Documents with missing <code>author.name.keyword</code> appear first, others sorted Z to A

B Documents with <code>author.name.keyword</code> missing appear at the end, others sorted A to Z

C Documents are sorted by <code>author.name.keyword</code> descending ignoring missing

D Elasticsearch throws an error because <code>missing</code> is not a valid parameter

💡 Hint

Check the missing parameter usage in sorting.

The missing": "_last" option tells Elasticsearch to put documents missing the field at the end of the sorted list. The order": "asc" sorts the existing values alphabetically from A to Z.