Neo4j vs VoltDB: What are the differences?

Neo4j: The world’s leading Graph Database. Neo4j stores data in nodes connected by directed, typed relationships with properties on both, also known as a Property Graph. It is a high performance graph store with all the features expected of a mature and robust database, like a friendly query language and ACID transactions; VoltDB: In-memory relational DBMS capable of supporting millions of database operations per second. VoltDB is a fundamental redesign of the RDBMS that provides unparalleled performance and scalability on bare-metal, virtualized and cloud infrastructures. VoltDB is a modern in-memory architecture that supports both SQL + Java with data durability and fault tolerance.

Neo4j can be classified as a tool in the "Graph Databases" category, while VoltDB is grouped under "In-Memory Databases".

Some of the features offered by Neo4j are:

• intuitive, using a graph model for data representation
• reliable, with full ACID transactions
• durable and fast, using a custom disk-based, native storage engine

On the other hand, VoltDB provides the following key features:

• In-Memory Performance with On-Disk Durability
• Transparent Scalability with Data Consistency
• NewSQL – All the benefits of SQL with Unlimited Scalability

"Cypher – graph query language" is the top reason why over 55 developers like Neo4j, while over 4 developers mention "SQL + Java" as the leading cause for choosing VoltDB.

Neo4j is an open source tool with 6.56K GitHub stars and 1.62K GitHub forks. Here's a link to Neo4j's open source repository on GitHub.