Cluster, node, and shard architecture in Elasticsearch - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is an Elasticsearch cluster?

An Elasticsearch cluster is a group of one or more nodes (servers) that together hold your entire data and provide indexing and search capabilities. It acts like a team working together to handle data.

beginner

Define a node in Elasticsearch.

A node is a single server that is part of the Elasticsearch cluster. It stores data and participates in the cluster's indexing and search operations.

beginner

What is a shard in Elasticsearch?

A shard is a smaller piece of an index. Elasticsearch splits large indexes into shards to distribute data across nodes, making search and storage faster and more efficient.

intermediate

Why does Elasticsearch use shards?

Shards help spread data across multiple nodes, allowing Elasticsearch to handle large amounts of data and perform searches quickly by working in parallel.

intermediate

Explain the difference between primary and replica shards.

Primary shards hold the original data, while replica shards are copies of primary shards. Replicas provide fault tolerance and improve search speed by sharing the load.

What does an Elasticsearch cluster consist of?

A Only shards without nodes

B A single node only

C Multiple nodes working together

D A database server

An Elasticsearch cluster is made up of multiple nodes that work together to store and search data.

What is the role of a node in Elasticsearch?

A It stores data and participates in search and indexing

B It only manages user access

C It is a backup server outside the cluster

D It only handles network traffic

A node stores data and helps with indexing and searching within the cluster.

Why are shards important in Elasticsearch?

A They backup data to external storage

B They encrypt data for security

C They compress data to save space

D They split data to improve speed and scalability

Shards split large indexes into smaller parts to distribute data and speed up search and storage.

What is a replica shard?

A A shard that holds user credentials

B A copy of a primary shard for fault tolerance

C A shard that is deleted after indexing

D A shard that stores metadata only

Replica shards are copies of primary shards that help with fault tolerance and load balancing.

How does Elasticsearch improve search speed?

A By distributing shards across nodes to search in parallel

B By storing all data on a single node

C By disabling replicas

D By limiting the number of nodes

Elasticsearch spreads shards across nodes so searches can happen at the same time on different parts of data.

Describe how clusters, nodes, and shards work together in Elasticsearch.

Think of a cluster as a team, nodes as team members, and shards as tasks shared among them.

Explain why Elasticsearch uses replica shards and how they help the system.

Consider how having backups and helpers can keep a system running smoothly.