Elasticsearch Interview Questions and Answers

In Elasticsearch, the nodes are added to enhance the quality and reliability of the cluster. There can be of the master node to control the entire cluster and also a basic data node. In order to add a node follows the steps-

• You have to set up a new Elasticsearch instance
• Specify its name in the cluster.name attribute
• Begin the Elasticsearch and node will be created

Note: This is one of the basic Elasticsearch interview questions but an important one.

Split brain is a consequence that generates when the master nodes in the cluster fail. In the bunch of clusters if any master node fails, then the slave node can choose a new master note for the effective functionality. In case the former one gets restore or comes into the functioning again, then it leads to the conflict. This problem also rises when communication is failed among the nodes.

Elasticsearch has its own query domain where the queries can be defined in the JSON format. Elasticsearch serves domain specific language DSL queries that make it easy to resolve real-world queries. Broadly Elasticsearch is divided into the following two different types of queries which ultimately solve multiple other queries associated with them. The list of them is-

• Full-text queries - this includes the multi-match query, match phrase prefix query, match query, common terms query and many more
• Term level queries - this includes the term query, term set query, existing query, ids query, wildcard query, and lot more.

In Elasticsearch, Type signifies the class of similar data. It can signify a name for making and is beneficial for the abstractions or for indicating the similar yet not identical data.

Cluster is a collection of one or multiple servers which consists of the data and also serves the federated indexing across all the different nodes. By default, a cluster can be identified by a significant name, i.e., Elasticsearch.

Being the open source and highly distributive network Elasticsearch has many advantages.

• It is a document-oriented platform
• Elasticsearch supports multiple search options
• A large number of complicated queries can be executed speedily with Elasticsearch
• In order to avoid the chance of data loss, Elasticsearch manages the record.
• Elasticsearch also supports indexing and multi-tenancy

Elasticsearch is a full-text searchable engine which is based on Lucerne. Generally, Elasticsearch was released as an open source platform which was developed in JavaScript under the Apache license terms. Using the phrase "multi-tenant and capable full-text search," Elasticsearch can be justified shortly. It has an HTTP interface for web and schema-free JSON files. As it is developed in Javascript, it can index the documents in variedly diverse formats.

Elasticsearch promotes the indexing of documents targeting the repository. Elasticsearch stores and executes the data as it converts the initial form of files into the internal documents and secures them with the basic data structure resembling with the JSON objects.

Below mentioned are a few steps to install Elasticsearch in windows -

• Download the zip file from relevant sources(websites)
• Install it and launch through GUI
• Carefully select the configuration and logs directories
• Now choose to install it as service or manually
• Finish the configuration steps carefully; it will be followed as cluster name, node, etc
• Select the plug-in

In Elasticsearch, an ingest node is a type of note that can be utilized during the documentation process before indexing. It is a part of the Elasticsearch cluster, and it intercepts the index request and bulk applying the transformation and later passes it back to the index.

The quorum by default, is set to action.write_onsistency. in case the quorum is not fulfilled then the index returns after the timeout with an error. Elasticsearch documentation follows the rule for write_consiatency level in quorum as quorum(>replicas/2+1).