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Advantages and disadvantages of type characteristics

Relational database

SQLite 、 Oracle 、 mysql

1. A relational database refers to a database that uses a relational model to organize data.

2. The most important feature of relational database is the consistency of transactions.

3. To put it simply, the relational model refers to the two-dimensional table model, and a relational database is a data organization composed of two-dimensional tables and their relationships.

1. Easy to understand: two-dimensional table structure is a concept very close to the logical world, and the relational model is easier to understand than other models such as mesh, hierarchy and so on.

2. Easy to use: the general SQL language makes it very convenient to operate relational databases.

3. Easy to maintain: rich integrity (physical integrity, referential integrity, and user-defined integrity) greatly reduces the probability of data redundancy and data inconsistency

4. Support SQL, which can be used for complex queries.

1. The huge price paid for maintaining consistency is its poor reading and writing performance.

2. Fixed table structure

3. High concurrent read and write requirements

4. Efficient reading and writing of massive data

Non-relational database

MongoDb 、 redis 、 HBase

1. Use key-value pairs to store data

2. Distributed

3. Generally, ACID is not supported.

4. Strictly speaking, non-relational database is not a kind of database, but a collection of structured data storage methods.

1. There is no need to parse in the sql layer, and the read and write performance is very high.

2. Based on the key-value pair, the data is not coupled and is easy to expand.

3, storage data format: nosql storage format is key,value form, document form, picture form and so on, document form, picture form and so on, while relational database only supports basic types.

1. Without sql support, the cost of learning and using is high.

2. No transaction processing, and poor support for additional functions such as bi and reports.

Note 1: database transactions must have ACID characteristics, ACID is Atomic atomicity, Consistency consistency, Isolation isolation, Durability persistence.

Note 2: the persistent storage of data, especially the persistent storage of massive data, still needs a relational database.

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