ElasticSearch interview questions

ElasticSearch interview questions Download ElasticSearch interview questions PDF

ElasticSearch interview questions

The aggregation framework provides aggregated data based on search query.It can be seen as a unit of work that builds analytic information over the set of documents.There are different types of aggregations with different purpose and outputs.
An index in Elasticsearch is similar to a table in relational databases.The only difference lies in storing the actual values in the relational database, whereas that is optional in Elasticsearch.
An index is capable of storing actual or analyzed values in an index.
Elasticsearch is a distributed documented store with several directories.It can store and retrieve the complex data structures that are serialized as JSON documents in real time.
Mapping is a process which defines how a document is mapped to the search engine, searchable characteristics are included such as which fields are tokenized as well as searchable.
In Elasticsearch an index created may contain documents of all “mapping types”.
It is a set or a collection of one or more than one nodes or servers that hold your complete data and offers federated indexing and search capabilities across all the nodes.It is identified by a different and unique name that is “Elasticsearch” by default.
This name is considered to be important because a node can be a part of a cluster only if it is set up to join the cluster by its name.
To delete an index in Elasticsearch use the command DELETE /index name.

Ex: DELETE /website

Each and every instance of Elasticsearch is a node.And, a collection of multiple nodes which can work in harmony form an Elasticsearch cluster.
Yes, Elasticsearch can be used as a replacement for a database as the Elasticsearch is very powerful.
It offers features like multitenancy, sharding and Replication, distribution and cloud Realtime get, Refresh, commit, versioning and re-indexing and many more, which make it an apt replacement of a database.
As on March 2018, the version 6.2.2 is the latest and stable version of Elasticsearch.
Each shard in elastic search has again two copies of the shard that are called the replicas.
They serve the purpose of fault tolerance and high availability.
Since Elasticsearch is built using Java, we require any of the following software to run Elasticsearch on our device.
  • The latest version of Java 8 series
  • Java version 1.8.0_131 is recommended.