A distributed real-time search and analytics engine
Elasticsearch is built on top of Apache Lucene. It is a “full text search engine” library. Elasticsearch is a wrapper around Lucene, it hides the internal details of Lucene behind a coherent, REST API. It can be described as:
- a distributed real-time document store where every field is indexed and search-able.
- “Distributed” - the data is sharded and partitioned.
- Real time - the new documents are index online and are immediately available for query
- Document Store - Elasticsearch accepts json documents
Elasticsearch has sensible defaults and is usable out of the box. It is also highly configurable, all the components are configurable and flexible.
Marvel is a management and monitoring tool used for Elasticsearch. It has an interactive console called Sense. Recall we used this in the early days with Piyush
Elasticsearch comes as a binary which runs in the JVM. You just need Java installed on your machine to run Elasticsearch
A node is a running instance of Elasticsearch. A cluster is a group of nodes with the same cluster.name that are working together to share data and to provide failover and scale,
If you don’t change the cluster.name, your nodes could join other nodes in a different cluster on the same network.
API to shutdown Elasticsearch : curl -XPOST 'http://localhost:9200/_shutdown'
Elasticsearch can be reached by 2 means:
- Java API
When using Java, you can use these
- Node Client
It joins a cluster as a non data node, it doesn’t hold the data itself, it knows where the data lives.
- Transport Client
It is lighter weight client and can be used to transport client to a remote cluster.
Both the clients use a custom elasticsearch transport protocol to talk to the cluster.
- RESTful API with JSON over HTTP
All other languages can communicate with Elasticsearch over port 9200 using a RESTful API
Elasticsearch uses JavaScript Object Notation (JSON) as the serialization format for documents.
JSON allows for rich information storage which can be difficult if we move to a tabular structure.