📅 最后修改于: 2020-11-22 06:49:37 🧑 作者: Mango
Cassandra是NoSQL数据库。 NoSQL数据库的主要目标是具有以下三点：
NoSQL比关系数据库管理系统快，因为与关系数据库相比，它使用不同的数据结构。
Cassandra数据结构比关系数据库结构快。 NoSQL数据库主要用于Bigdata和实时Web应用程序中。
| NoSQL Database | Relational Database |
|---|---|
| NoSQL Database supports a very simple query language. | Relational Database supports a powerful query language. |
| NoSQL Database has no fixed schema. | Relational Database has a fixed schema. |
| NoSQL Database is only eventually consistent. | Relational Database follows acid properties. (Atomicity, Consistency, Isolation, and Durability) |
| NoSQL databases don’t support transactions (support only simple transactions). | Relational Database supports transactions (also complex transactions with joins). |
| NoSQL Database is used to handle data coming in high velocity. | Relational Database is used to handle data coming in low velocity. |
| The NoSQL?s data arrive from many locations. | Data in relational database arrive from one or few locations. |
| NoSQL database can manage structured, unstructured and semi-structured data. | Relational database manages only structured data. |
| NoSQL databases have no single point of failure. | Relational databases have a single point of failure with failover. |
| NoSQL databases can handle big data or data in a very high volume . | NoSQL databases are used to handle moderate volume of data. |
| NoSQL has decentralized structure. | Relational database has centralized structure. |
| NoSQL database gives both read and write scalability. | Relational database gives read scalability only. |
| NoSQL database is deployed in horizontal fashion. | Relation database is deployed in vertical fashion. |