Cache management (query, request, field data) in Elasticsearch - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the purpose of query cache in Elasticsearch?

Query cache stores the results of frequently run queries to speed up response times by avoiding repeated computation.

intermediate

How does request cache differ from query cache in Elasticsearch?

Request cache stores the results of entire search requests, including filters and aggregations, while query cache focuses on caching filter results only.

beginner

What type of data does the field data cache hold in Elasticsearch?

Field data cache holds in-memory data structures for sorting, aggregations, and scripting on text or keyword fields.

intermediate

Why is it important to monitor and manage field data cache in Elasticsearch?

Because field data cache can consume a lot of heap memory, unmanaged growth can cause out-of-memory errors and degrade cluster performance.

intermediate

How can you disable request cache for a specific search request in Elasticsearch?

By setting the parameter "request_cache": false in the search request body, you can disable request caching for that request.

Which cache in Elasticsearch stores results of filters to speed up queries?

A Shard cache

B Query cache

C Field data cache

D Request cache

Query cache stores filter results to speed up repeated queries.

What does the request cache in Elasticsearch store?

A Only filter results

B Index mappings

C Field data for sorting

D Entire search request results including aggregations

Request cache stores full search request results, including filters and aggregations.

Why should field data cache be carefully managed?

A It consumes heap memory and can cause out-of-memory errors

B It can cause slow network traffic

C It uses disk space

D It slows down indexing

Field data cache uses heap memory and unmanaged growth can cause memory errors.

How do you disable request cache for a search request?

A Set "request_cache": false

B Set "query_cache": false

C Set "cache": false

D Set "fielddata_cache": false

Setting "request_cache": false disables request caching for that search request.

Which cache is used to speed up sorting and aggregations on text fields?

A Query cache

B Request cache

C Field data cache

D Filter cache

Field data cache holds data structures needed for sorting and aggregations.

Explain the differences between query cache, request cache, and field data cache in Elasticsearch.

Think about what each cache stores and why.

Describe why managing field data cache is important and how it affects Elasticsearch performance.

Consider memory usage and cluster health.