📅 最后修改于: 2020-11-26 05:09:35 🧑 作者: Mango
OrientDB是一个开源NoSQL数据库管理系统。 NoSQL数据库提供了一种存储和检索NO关系或NON关系数据的机制，该关系是指除表格数据之外的其他数据，例如文档数据或图形数据。 NoSQL数据库越来越多地用于大数据和实时Web应用程序中。 NoSQL系统有时也称为“不仅SQL”，以强调它们可能支持类似SQL的查询语言。
OrientDB也属于NoSQL家族。 OrientDB是第二代分布式图形数据库，具有Apache 2许可证开源的一种产品中的文档灵活性。 OrientDB之前市场上有几种NoSQL数据库，其中之一是MongoDB。
MongoDB和OrientDB包含许多共同的功能，但是引擎根本不同。 MongoDB是纯文档数据库，而OrientDB是带有图形引擎的混合文档。
| Features | MongoDB | OrientDB |
|---|---|---|
| Relationships | Uses the RDBMS JOINS to create relationship between entities. It has high runtime cost and does not scale when database scale increases. | Embeds and connects documents like relational database. It uses direct, super-fast links taken from graph database world. |
| Fetch Plan | Costly JOIN operations. | Easily returns complete graph with interconnected documents. |
| Transactions | Doesn’t support ACID transactions, but it supports atomic operations. | Supports ACID transactions as well as atomic operations. |
| Query language | Has its own language based on JSON. | Query language is built on SQL. |
| Indexes | Uses the B-Tree algorithm for all indexes. | Supports three different indexing algorithms so that the user can achieve best performance. |
| Storage engine | Uses memory mapping technique. | Uses the storage engine name LOCAL and PLOCAL. |
OrientDB是第一个多模型开源NoSQL DBMS，它将图形的功能和文档的灵活性整合到一个可扩展的高性能操作数据库中。