Parisa Delfani - Lorestan University ,Khorramabad,Iran
Parastou Alavi - Lorestan University ,Khorrramabad,Iran
Ehsan Azizi Khadem - Lorestan University, Khorramabad, Iran

—Most graph databases are NoSQL in nature and store their data in a key-value store or document-oriented databases. In general terms, they can be considered to be key-value databases with the additional relationship concept added. Relationships allow the values in the store to be related to each other in a free form way, as opposed to traditional relational databases where therelationships are defined within the data itself. These relationships allow complex hierarchies to be quickly traversed, addressing one of the more common performance problems found in traditional key-value stores. Most graph databases also add the concept of tags or properties, which are essentially relationships lacking a pointer to another document. In computing, a graph database is a database that uses graph structures for semantic queries with nodes, edges and properties to represent and store data. In this article, we define the graph databases neo4j, graphdb, Sesame, AllegroGraph , dex first, then we compare the features of each together.