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

Source: Internet
Author: User

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.


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






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






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



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


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


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


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