Elasticsearch is an open source NoSQL database that can downloaded here.
- Elasticsearch is a search engine that was designed to work on the cloud.
- It uses a distributed search engine that isn't based on a single central server.
- Elasticsearch allows for running searches in close to realtime.
- It supports multiple search indexes.
- Indexes are sharded so that the load can be spread among multiple database servers.
- Each shard is a Lucene index.
- It's a schema free database - it uses documents rather than tables. You don't need to begin with a structure of rows and columns.
Relativity Data Grid uses Elasticsearch with the Audit application, which runs reports on user activity.