Index mappings overview in Elasticsearch - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is an index mapping in Elasticsearch?

An index mapping defines how documents and their fields are stored and indexed in Elasticsearch. It tells Elasticsearch the data types and rules for each field.

beginner

Why do we need to define data types in index mappings?

Data types help Elasticsearch understand how to store, search, and sort the data correctly. For example, numbers, dates, and text are handled differently.

intermediate

What happens if you don't define a mapping for a field in Elasticsearch?

Elasticsearch tries to guess the data type automatically using dynamic mapping. But this can lead to unexpected results or inefficient searches.

intermediate

How can you change a field's mapping after the index is created?

You cannot change a field's mapping directly after creation. Instead, you create a new index with the desired mapping and reindex your data.

beginner

What is the difference between 'text' and 'keyword' data types in Elasticsearch mappings?

'text' is used for full-text search and is analyzed (broken into words). 'keyword' is for exact matches and sorting, stored as is without analysis.

What does an Elasticsearch index mapping define?

A The hardware requirements for Elasticsearch

B The network settings of Elasticsearch

C The user permissions for the index

D How documents and fields are stored and indexed

Index mapping defines how documents and their fields are stored and indexed in Elasticsearch.

Which data type should you use for full-text search in Elasticsearch?

A keyword

B integer

C text

D date

'text' type is used for full-text search because it is analyzed into words.

What happens if you add a new field without defining it in the mapping?

A Elasticsearch guesses the data type using dynamic mapping

B You must restart Elasticsearch

C The field is ignored

D Elasticsearch rejects the document

Elasticsearch uses dynamic mapping to guess the data type automatically.

Can you change a field's data type in an existing Elasticsearch index mapping?

A No, you must create a new index and reindex

B Yes, anytime

C Only if the index is empty

D Only for text fields

You cannot change a field's mapping after creation; you must create a new index and reindex data.

Which mapping type is best for sorting exact values?

A text

B keyword

C date

D boolean

'keyword' type stores exact values and is best for sorting and filtering.

Explain what an Elasticsearch index mapping is and why it is important.

Think about how Elasticsearch knows what kind of data each field holds.

Describe the difference between 'text' and 'keyword' data types in Elasticsearch mappings and when to use each.

Consider searching for words versus filtering exact values.