Index templates in Elasticsearch - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is an index template in Elasticsearch?

An index template is a set of rules and settings that automatically apply to new indices matching a pattern. It helps keep index settings, mappings, and aliases consistent.

beginner

Which parts can you define in an Elasticsearch index template?

You can define index patterns, settings (like number of shards), mappings (field types), and aliases in an index template.

intermediate

How does Elasticsearch decide which template to apply when creating a new index?

Elasticsearch applies templates whose index patterns match the new index name. If multiple templates match, it merges them by priority.

intermediate

What is the difference between index_patterns and template in an index template?

index_patterns defines which index names the template applies to. template contains the actual settings, mappings, and aliases to apply.

beginner

Why use index templates instead of setting index settings manually each time?

Index templates save time and avoid mistakes by automatically applying consistent settings and mappings to new indices matching patterns.

What does an Elasticsearch index template primarily control?

A Cluster-wide configurations

B Data stored inside an index

C User access permissions

D Settings, mappings, and aliases for new indices

Index templates define settings, mappings, and aliases that apply automatically to new indices matching the template pattern.

Which field in an index template specifies which indices it applies to?

A index_patterns

B template

C aliases

D settings

index_patterns lists the index name patterns that the template matches.

If two templates match the same index, how does Elasticsearch decide which settings to use?

A It merges templates by priority, higher priority wins

B It uses the template with the lowest priority

C It randomly picks one template

D It ignores both templates

Elasticsearch merges matching templates by priority, applying higher priority templates last.

Can index templates be updated after creation?

A No, they are fixed once created

B Yes, you can update them and new indices will use updated templates

C Only mappings can be updated

D Only settings can be updated

You can update index templates anytime; new indices created after update use the new template.

What happens if no index template matches a new index name?

A Index creation fails

B Elasticsearch applies a random template

C Index is created with default settings

D Index is created but with no mappings

If no template matches, Elasticsearch creates the index with default settings and mappings.

Explain what an Elasticsearch index template is and why it is useful.

Think about how you can save time and avoid errors when creating many similar indices.

Describe how Elasticsearch applies multiple index templates when creating a new index.

Consider what happens if two templates want to set different shard counts.