ElasticSearch ElasticSearch 2 — Questions and Answers
Question 1: What is the default number of primary shards for an index created in Elasticsearch 7.x and later?
- 5
- 3
- 1 (Correct answer)
- 10
Correct answer: 1
Starting with Elasticsearch 7.0, the default number of primary shards per index was changed from 5 to 1.
Question 2: Which Elasticsearch query type is used to find documents where a field value falls within a specified range?
- term query
- match query
- range query (Correct answer)
- exists query
Correct answer: range query
The range query returns documents where a field value falls within a specified range using gte, gt, lte, or lt parameters.
Question 3: What does the `_source` field in an Elasticsearch document contain?
- The index routing key
- The original JSON document as indexed (Correct answer)
- The analyzed tokens for each field
- The document's shard assignment
Correct answer: The original JSON document as indexed
The `_source` field stores the original JSON body of the document as it was passed at index time.
Question 4: Which aggregation type in Elasticsearch computes the average value of a numeric field?
- stats aggregation
- avg aggregation (Correct answer)
- value_count aggregation
- extended_stats aggregation
Correct answer: avg aggregation
The avg aggregation is a single-value metrics aggregation that computes the average of numeric values extracted from the aggregated documents.
Question 5: What is the purpose of the Elasticsearch `alias` feature?
- To create a secondary name pointing to one or more indices (Correct answer)
- To replicate data across clusters
- To define custom analyzers for fields
- To snapshot indices to remote storage
Correct answer: To create a secondary name pointing to one or more indices
An alias is a secondary name for one or more indices, enabling zero-downtime reindexing and abstracting the underlying index name from applications.
Question 6: Which HTTP method is used to update an existing document using the Elasticsearch Update API?
- PUT
- PATCH
- POST (Correct answer)
- GET
Correct answer: POST
The Update API uses a POST request to `/<index>/_update/<id>` to perform partial document updates or script-based updates.
Question 7: What does the `doc_values` field mapping parameter control in Elasticsearch?
- Whether the field is searchable via full-text search
- On-disk data structures used for sorting and aggregations (Correct answer)
- The number of terms stored in the inverted index
- The maximum field value allowed during indexing
Correct answer: On-disk data structures used for sorting and aggregations
doc_values are on-disk data structures stored at index time that enable efficient sorting, aggregations, and access in scripts.
ElasticSearch ElasticSearch 2
What is the default number of primary shards for an index created in Elasticsearch 7.x and later?