The role of the default self-bringing database after MySQL installation

Everyone in the study of MySQL, after installation will find that the inside has brought a few default database, I installed the MySQL5.5 inside with six databases

　　

Some information on the internet on the functions of these databases to do some learning.

1.information_schema

There are many tables in this library.

　　

　　

Information_schema database Table Description:

Schemata Table: Provides information for all databases in the current MySQL instance. This table is the result of show databases.

Tables Table: Provides information about the tables in the database, including views. Describes in detail which schema, table type, table engine, creation time, and so on, a table belongs to. This table is the result of show tables from SchemaName.

Columns table: Provides the column information in the table. Describes in detail all the columns of a table and the information for each column. This table is the result of show columns from Schemaname.tablename.

Statistics Table: Provides information about the index of a table. This table is the result of show index from Schemaname.tablename.

User_privileges (User Rights) Table: gives information about the full range of permissions. This information is derived from the Mysql.user authorization form. Non-standard tables.

Schema_privileges (Program permissions) Table: Provides information about schema (database) permissions. This information is from the Mysql.db authorization form. Non-standard tables.

Table_privileges (table permissions) Table: Gives information about table permissions. This information is derived from the Mysql.tables_priv authorization form. Non-standard tables.

Column_privileges (column permissions) Table: Gives information about column permissions. This information is derived from the Mysql.columns_priv authorization form. Non-standard tables.

Character_sets (character Set) Table: Provides information about the available character sets for MySQL instances. This table is the show CHARACTER set result set.

Collations table: Provides cross-reference information about each character set.

Collation_character_set_applicability table: Indicates the character set that can be used for proofreading. These columns are equivalent to the first two display fields of show collation.

Table_constraints table: A table describing the existence of constraints. And the constraint type of the table.

Key_column_usage table: Describes the key columns that have constraints.

Routines Table: Provides information about storing subroutines (stored programs and functions). At this point, the routines table does not contain a custom function (UDF). A column named "Mysql.proc name" indicates the corresponding INFORMATION_SCHEMA. The Mysql.proc table column for the routines table.

Views Table: Gives information about the view in the database. You need to have show views permission, otherwise you cannot view the view information.

Triggers table: Provides information about the triggering program. You must have super privileges to view the table

　　

2.mysql

　　

3.performance_schema

　　

Need to set parameters: Performance_schema to start this function

According to the relevant standards of the event statistics, the table is read-only, can only turcate

Events_waits_summary_by_instance

Events_waits_summary_by_thread_by_event_name

Events_waits_summary_global_by_event_name

File_summary_by_event_name

File_summary_by_instance

Setup_consumers describe various events

Setup_instruments describes the name of the table under this database and whether to turn on monitoring.

Setup_timers describes the time interval at which the monitoring option has sampled frequency

Events_waits_current records the waiting events that are currently occurring, which is a read-only table, cannot update, delete, but can truncate

Performance history table: Events_waits_history keeps only the last 10 events per thread (thread)

Performance history table: Events_waits_history_long records The most recent 10,000 Events standard FIFO (FIFO) both tables are read-only and can only be truncate

4.sakila

　　

This is a MySQL sample database, inside are some examples of the table.

5.test

　　This is an empty table, and the test table can be deleted.

6.world

　　

　　There's no big use for this watch, there's a lot of data in these three tables. Future progress will continue to add.