Dynamic templates in Elasticsearch - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the mapping result of this dynamic template?

Given the following dynamic template in an Elasticsearch index mapping, what will be the data type of fields named user_email and user_age?

Elasticsearch

{
  "mappings": {
    "dynamic_templates": [
      {
        "strings_as_keywords": {
          "match_mapping_type": "string",
          "mapping": {
            "type": "keyword"
          }
        }
      },
      {
        "integers_as_long": {
          "match_mapping_type": "long",
          "mapping": {
            "type": "long"
          }
        }
      }
    ]
  }
}

A user_email: keyword, user_age: long

B user_email: text, user_age: integer

C user_email: keyword, user_age: integer

D user_email: text, user_age: long

💡 Hint

Look at the match_mapping_type and the mapping type for each template.

The dynamic template matches string fields and maps them as keyword. It matches long fields and maps them as long. So user_email (a string) becomes keyword and user_age (a long) becomes long.

🧠 Conceptual

intermediate

Which dynamic template matches fields ending with '_id'?

Which dynamic template configuration will match any field name that ends with _id and map it as a keyword type?

A { "match": "*_id", "mapping": { "type": "keyword" } }

B { "match_pattern": "regex", "match": ".*_id$", "mapping": { "type": "keyword" } }

C { "match": "_id", "mapping": { "type": "keyword" } }

D { "match_pattern": "wildcard", "match": "*_id", "mapping": { "type": "keyword" } }

💡 Hint

Use match_pattern with regex to match field name endings.

To match fields ending with _id, you need a regex pattern .*_id$ and specify match_pattern": "regex". Option B correctly uses this.

🔧 Debug

advanced

Why does this dynamic template cause a mapping error?

Consider this dynamic template snippet. Why will it cause an error when applied?

Elasticsearch

{
  "dynamic_templates": [
    {
      "strings_as_text": {
        "match_mapping_type": "string",
        "mapping": {
          "type": "text",
          "fields": {
            "keyword": {
              "type": "keyword"
            }
          }
        }
      }
    },
    {
      "strings_as_keyword": {
        "match": "*_id",
        "mapping": {
          "type": "keyword"
        }
      }
    }
  ]
}

A The templates conflict because both match string fields, causing a mapping conflict error.

B The first template's nested fields are not allowed inside dynamic templates.

C The second template's match pattern is invalid because it uses '*' instead of '?' wildcard.

D The second template uses wildcard match without specifying match_pattern, causing an error.

💡 Hint

Check if the wildcard pattern requires a special setting.

When using wildcards in match, you must specify match_pattern": "wildcard". Without it, the pattern is treated as a literal string, causing an error.

📝 Syntax

advanced

Identify the syntax error in this dynamic template

What is the syntax error in this dynamic template snippet?

Elasticsearch

{
  "dynamic_templates": [
    {
      "template_1": {
        "match_mapping_type": "string",
        "mapping": {
          "type": "keyword"
        }
      }
    },
    {
      "template_2": {
        "match": "*_date",
        "mapping": {
          "type": "date"
        }
      }
    }
  ]
}

A The second template uses wildcard match but lacks match_pattern specification.

B Missing comma after the first template object inside the array.

C The mapping type 'date' is invalid in dynamic templates.

D The dynamic_templates array must contain only one template object.

💡 Hint

Check the use of wildcards in match fields.

When using wildcards in match, you must specify match_pattern": "wildcard". Without it, the pattern is treated literally, causing the template not to match as expected.

🚀 Application

expert

How many fields will be mapped as 'text' in this dynamic template setup?

Given this dynamic template configuration, how many fields will be mapped as text if the document contains fields: title, description, user_id, created_at?

Elasticsearch

{
  "dynamic_templates": [
    {
      "strings_as_text": {
        "match_mapping_type": "string",
        "unmatch": "*_id",
        "mapping": {
          "type": "text"
        }
      }
    },
    {
      "ids_as_keyword": {
        "match": "*_id",
        "mapping": {
          "type": "keyword"
        }
      }
    },
    {
      "dates_as_date": {
        "match_mapping_type": "date",
        "mapping": {
          "type": "date"
        }
      }
    }
  ]
}

A 1

B 3

C 2

D 4

💡 Hint

Check which fields match each template and consider the unmatch clause.

Fields title and description are strings and do not end with _id, so they match the first template and become text. user_id matches the second template and becomes keyword. created_at matches the third template as date. So only 2 fields are mapped as text.