Since I haven't understood a thing from the conceptual level for a long time, most of the people who understand the database now focus on performance issues. Of course, it is very important. Sometimes it is more important to understand the concept.
---Foreword
Reprint address: Reprint source
1. Relational databases establish the relationship between tables through foreign key associations. 2. Non-relational databases usually refer to data stored in the database in the form of objects, and the relationship between objects is through the attributes of each object itself. to decide
| database type |
characteristic | advantage | shortcoming |
| Relational database SQLite, Oracle, mysql |
1. A relational database refers to a database that uses a relational model to organize data; 2. The biggest feature of a relational database is the consistency of transactions; 3. Simply put, a relational model refers to a two-dimensional table model, while a A relational database is a data organization composed of two-dimensional tables and the connections between them. |
1. Easy to understand: The two-dimensional table structure is a concept that is very close to the logical world, and the relational model is easier to understand than other models such as mesh and hierarchy; 2. Easy to use: the general SQL language makes it very convenient to operate relational databases; 3. Easy to maintain: Rich integrity (entity integrity, referential integrity and user-defined integrity) greatly reduces the probability of data redundancy and data inconsistency; 4. Supports SQL, which can be used for complex queries. |
1. The huge price paid for maintaining consistency is its poor read and write performance; 2. Fixed table structure; 3. High concurrent read and write requirements; 4. Efficient read and write of massive data; |
| Non-relational database MongoDb, redis, HBase |
1. Use key-value pairs to store data; 2. Distributed; 3. Generally, ACID features are not supported; 4. Non-relational database is not strictly a database, but a collection of data structured storage methods. |
1. It does not need to go through the analysis of the sql layer, and the read and write performance is very high; 2. Based on key-value pairs, the data has no coupling and is easy to expand ; Image form, etc., document form, image form, etc., while relational databases only support basic types. |
1. No sql support is provided, and the cost of learning and use is high; 2. There is no transaction processing, and the support for additional functions such as bi and reports is not good; |