Titan并不是数据库；它是一个数据库之上的客户端库。它依赖于下面的存储引擎，比如Cassandra或者Hadoop，来存储其数据。它也依赖于索引引擎，比如Lucene、ElasticSearch或者Solr，来执行相关的查询。
Titan 是一个在服务器集群搭建的分布式的图形数据库，特别为存储和处理大规模图形而优化。集群很容易扩展以支持更大的数据集，Titan有一个很好的插件式性能，这个性能让它搭建在一些成熟的数据库技术上像 Apache Cassandra、Apache HBase、 Oracle BerkeleyDB。插件式索引架构可以整合 ElasticSearch 和Lucene技术。内置实现 Blueprints graph API，支持 TinkerPop所有的技术。
Titan is a scalable graph database optimized for storing and querying graphs containing hundreds of billions of vertices and edges distributed across a multi-machine cluster. Titan is a transactional database that can support thousands of concurrent users executing complex graph traversals in real time.
In addition, Titan provides the following features:
Elastic and linear scalability for a growing data and user base.
Data distribution and replication for performance and fault tolerance.
Multi-datacenter high availability and hot backups.
Support for ACID and eventual consistency.
Support for various storage backends:
Apache Cassandra
Apache HBase
Oracle BerkeleyDB
Support for global graph data analytics, reporting, and ETL through integration with big data platforms:
Apache Spark
Apache Giraph
Apache Hadoop
Support for geo, numeric range, and full-text search via:
ElasticSearch
Solr
Lucene
Native integration with the TinkerPop graph stack:
Gremlin graph query language
Gremlin graph server
Gremlin applications
Open source with the liberal Apache 2 license.
特性
1,支持不同的分布式存储层
Apache Cassandra (distributed)
Apache HBase (distributed)
Oracle BerkeleyDB (local)
Persistit (local)
2 .可以更加数据集的大小和用户基数弹性扩展
3. 分布式存储的复制，高容错性
4,支持很多字符集和热备份
5,支持 ACID 和 eventual consistency（最终一致性）
6,支持的索引
ElasticSearch
Apache Lucene
7,内置实现 TinkerPop graph API
Gremlin graph query language
Frames object-to-graph mapper
Rexster graph server
Blueprints standard graph API