Four default databases for mysql 8.0

Four databases are automatically generated after mysql 8.0 installation is completed.

Information_schema

NFORMATION_SCHEMA provides access to database metadata, information about the MySQL server, such as the name of the database or table, the data type of the column, or access rights.

Refer to the official link for the role of each table in it.

Https://dev.mysql.com/doc/refman/8.0/en/information-schema.html

2.mysql

The core database of mysql is mainly responsible for storing the control and management information that mysql needs to use, such as users, permissions, keywords and so on.

3.perfrmace_schema

Performance_schema is mainly used to collect the performance parameters of the database, which is implemented using the PERFORMANCE_SCHEMA storage engine and the performance_schema database. The performance mode focuses on performance data. This is different from what INFORMATION_SCHEMA uses to examine metadata.

Official link

Https://dev.mysql.com/doc/refman/8.0/en/performance-schema.html

4.sys

MySQL 8.0 contains sys schemas, a set of objects that help DBA and developers interpret the data collected by performance patterns. Sys schema objects can be used for typical tuning and diagnostic use cases. Objects in this schema include:

Summarize the Performance Schema data into a view in a form that is easier to understand.

Stored procedures that perform operations such as performance architecture configuration and generating diagnostic reports.

Storage function to query the performance schema configuration and provide formatting services.

Https://dev.mysql.com/doc/refman/8.0/en/sys-schema.html