What is the root cause of data inconsistency in the database?

In the database, the root cause of data inconsistency is: data redundancy. Data redundancy refers to the duplication between data; due to the repeated storage of data, when different applications use and modify different backups, it is easy to cause data inconsistency.

The operating environment of this tutorial: windows7 system, mysql8 version, Dell G3 computer.

Data redundancy is the root cause of data inconsistency.

Generally there are three reasons for data inconsistency in the database:

• The first is caused by data redundancy;

• The second is caused by improper concurrency control;

• The third is caused by data loss or data damage due to some reason (such as software and hardware failure or operation error) .

The first situation: data redundancy

Data redundancy refers to the duplication between data. It can also be said that the same data is stored in different data files. Phenomenon.

Due to the duplicate storage of data, when different applications use and modify different backups, it is easy to cause data inconsistency.

Suppose the user's address is placed in both tables in the database. When the user's address changes, if only the data in one table is updated, then the two tables will have inconsistent data.

Second case: Improper concurrency control

Suppose in the air ticket booking system, if two ticket purchase points query the ordering status of a certain ticket at the same time, and order this ticket respectively If concurrency control is improper, the same ticket will be sold to two users. Data inconsistency occurs because the system does not perform concurrency control or has improper concurrency control.

Third Situation: Faults and Errors

If software and hardware failure or operation errors lead to data loss or data damage, causing data inconsistency. Therefore, we need to provide some measures for database maintenance and database data recovery. The database must be restored to a correct, complete, and consistent state according to various database maintenance methods (such as dumping, logging, etc.) and data recovery measures.

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