MySQL Architecture

Review notes

Install here docker Installation is not elaborated here ：Docker install mysql5.7( Turn on binlog function 、 Modify character )_ Clock in the opposite direction 197 The blog of -CSDN Blog _docker mysql Turn on binlog

Catalog

1.MySQL Character set related operations

2.SQL Case specification

3.SQL_mode Setting up reasonable

4.MySQL Data directory for

5. The relationship between database and file system

6. Representation of database in file system

 7. User and permission management

7.1 User management

7.2 Rights management

7.3 Permissions on the table

8. Role management

9. Configuration file usage

10. Logical architecture

11.SQL Execute the process

12. Storage engine operation  

13. Storage engine introduction

---

1.MySQL Character set related operations

Add ：5.7 Version of view character set ：

show variables like 'character%';
 or 
show variables like '%char%';

  Character sets at all levels

1 Server level 、2 Database level 、3 Table level 、4 Column level         Character sets can be set for each character set

、

2.SQL Case specification

windows Case insensitive , stay linux Lower case sensitivity

0 Indicates case sensitivity ,1 Indicates case insensitive

# Check whether it is sensitive 
SHOW VARIABLES LIKE '%lower_case_table_names%'

windows

linux

Linux The rules ：

1、 Database name 、 Table name 、 The table alias 、 Variable names are strictly case sensitive ;

2、 keyword 、 The function name is in SQL Case insensitive in ;

3、 Name （ Or field name ） Alias with column （ Or field alias ） In all cases, case is ignored ;

---

Widows The rules ：

Case insensitive in

---

Set up Linux Case sensitive

stay mysql5.7 in ： need my.cnf Configuration of [mysqlId] Add lower_case_table_names=1 And restart the server

stay mysql8.0 in ： You need to delete /var/lib/mysql Catalog , Then modify the configuration file , start-up mysql

SQL Write suggestions

1. Then all keywords and function names are capitalized

2. Database name , Table name , Table alias , All field names are lowercase

3.sql Statement must be in ; ending

3.SQL_mode Setting up reasonable

The main function is to set different levels of data verification

Loose mode ：

give an example ： Set up name char(3), There are too many insertion times 3, such as abc123, At this time, the insertion will not report an error , And only insert abc

The main use of ： Data migration

Strict mode ：

For the loose model, this error reporting is the strict model

---

View and set up

see

select @@session.sql_mode;
 or 
select @@global.sql_mode;
 or 
show variables like 'sql_mode';

Temporary settings

set SESSION sql_mode='STRICT_TRANS_TABLES'; # overall situation  
set GLOBAL sql_mode='STRICT_TRANS_TABLES'; # Current session 

Permanent settings

stay my.cnf Modify... In configuration file , Restart again

[mysqld]
sql_mode=ONLY_FULL_GROUP_BY,STRICT_TRANS_TABLES,NO_ZERO_IN_DATE,NO_ZERO_DATE,ERROR_FOR _DIVISION_BY_ZERO,NO_ENGINE_SUBSTITUTION

4.MySQL Data directory for

windows Next

 Linux Next

linux see mysql Related documents                  find / -name mysql

  View the database storage path                 show variables like 'datadir'

5. The relationship between database and file system

View the default database                         show        database

6. Representation of database in file system

Two storage engines Innodb,MyIsAM

Innodb :

5.7:

ibdata1            Location ：/var/lib/mysql/qing    Table space of the system , Storing table data

Table name .frm           Description of the file structure

Table name .ibd          Represents the independent space of the table , Used to store the corresponding Table name .frm Data and index , Independent table space

---

SYSTEM tablespace and independent tablespace settings , stay my.cnf

[server] 
innodb_file_per_table=0 # 0： Represents the use of system tablespaces ; 1： Represents the use of independent tablespaces 

Check the default

show variables like 'innodb_file_per_table';

 8.0:

stay 8.0 in .frm and .ibd Amalgamated , Only .ibd 了

  Proof of merger ：

ibd2sdi --dumpfile= Create a piece name by yourself .txt  The file to parse .ibd

MyIsAM:

characteristic : Data and indexes are stored separately

Create table ：

5.7：

There are three files after creation

student_myisam.MYD  # Save table data 
student_myisam.MYI	# Storage index 
student_myisam_363.frm

8.0：

difference 5.7  .frm Turned into .sdi

 7. User and permission management

7.1 User management

Usually use mysql -u root -p password

Full version login

mysql -h  Host name ( Default localhost) -P  Port number  -p  password   Database name  -e sql sentence ;

To view the user

use mysql;
select Host,User from user;

Add users

# % Indicates that any address can be accessed 
create user 'qing' identified  by '123456';
#  Indicates that only local connections are supported 
create user 'qing'@'localhost' identified  by '83348535';

View current user permissions

#  View permissions 
show grants ;

Change user name

#  Change user name 
update mysql.user set User='ming' where User='qing';

Refresh the permissions

#  Refresh the permissions 
flush privileges ;

Delete account

#  Delete account 
drop user 'ming';
drop user 'ming'@'localhost';

Change the current user password

#  Set the password of the current user 
alter user user() identified by '83348535';
# Change the current password 
set password ='abc';

Change other user passwords

use mysql;
desc user;
# The password is specially encrypted 
select Host,User,authentication_string from user;
#  Change other user passwords 
alter user 'qing'@'%' identified by '123456';
set password for 'qing'@'%'=' password ';

7.2 Rights management

When you first started creating users , At this time, you need to give permission to Yongfu

  Show the current user permissions

#  View permissions 
show grants ;
#  or  
SHOW GRANTS FOR CURRENT_USER; 
#  or  
SHOW GRANTS FOR CURRENT_USER();
# View all permission lists 
show privileges;

View the user's global permissions

SHOW GRANTS FOR 'user'@' The host address ' ;

Authority granting principle ：

1. The minimum authority to meet the requirements

2. Restrict the user's Login Host , limit io Or the Internet IP paragraph

3. Set a password that meets the password complexity

4. Clean up unwanted users regularly

Authority granted to

ps: The created user has no way to create another user , If you give your permission to others

REVOKE  jurisdiction 1, jurisdiction 2,… jurisdiction n ON  Database name . The name of the table  FROM  user name @ Address of the user ;

Need to add parameters

with grant option

give an example ：

GRANT SELECT,INSERT,DELETE,UPDATE ON   database . surface  TO '[email protected]'@'%' 
​​​​​​​#  Assign all permissions to qing user 
grant all privileges on *.* to 'qing'@'%';

Take back authority

REVOKE  jurisdiction 1, jurisdiction 2,… jurisdiction n ON  Database name . The name of the table  FROM  user name @ Address of the user ;

give an example ：

ps： Re login is useful

# Take back all permissions of the whole database and table  
REVOKE ALL PRIVILEGES ON *.* FROM [email protected]'%'; 
# Take back mysql Insert, delete, modify and query permissions for all tables under the database  
REVOKE SELECT,INSERT,UPDATE,DELETE ON mysql.* FROM [email protected];

7.3 Permissions on the table

mysql Control users' access to data through permission table , The permission table is stored and then mysql In the database ,mysql According to the contents of the permission table, give each user the corresponding permission , These permissions are important for ,user surface ,db surface ,prcs_priv( Set operation permissions for stored procedures and stored functions ),tables_priv( Table authority ),colums_priv( List of permissions )

user surface ：

 db surface ：

It indicates the problem of permission to a specific database

desc tables_priv;

Indicates the corresponding permissions of a table

 desc columns_priv;

Whether the corresponding field of the corresponding data table has permission

desc procs_priv;

Set operation permissions for stored procedures and stored functions

8. Role management

8.0 Newly introduced concept , from oracle Borrowed concepts

Concept ： Roles are sets of permissions , You can add or move permissions for roles , Users are given roles , At the same time, they are also given the right to feel . And like an account , Role ownership is granted and revoked .

In short ：mysql There are multiple accounts , There are multiple roles in the account

ps: When a role is created, it does not have corresponding permissions , You need to activate yourself

Create the role

#  Create the role   For more than one character , Connection No 
create role 'manager'@'%';
#  To give permission 
grant select,update on  database .* to ' role ';

View role permissions

show grants for ' role '@'%';

Recycling permissions

REVOKE  jurisdiction  ON  Table name FROM ' role ';

give an example ：

# Revoke authority 
REVOKE INSERT, UPDATE, DELETE ON school.* FROM 'school_write';
# View permissions 
SHOW GRANTS FOR 'school_write';

  Delete the role

# Multiple use , Connected to a 
DROP ROLE ' role ';

Give permission to the user

GRANT ' role ' TO ' Roles granted '@'localhost';
SHOW GRANTS FOR ' Roles granted '@'localhost';

Activate role

1. Administrator activation

# Use set default role  The command activates the character 
SET DEFAULT ROLE ALL TO ' role '@'localhost';

2. Parameter setting , Default activation

# Check to see if 
show variables like 'activate_all_roles_on_login';
# hold off Change to on
SET GLOBAL activate_all_roles_on_login=ON;

Revoke user activation

REVOKE role FROM user;

give an example :

# Revoke user information 
# revoke kangshifu User school_read role .
REVOKE 'school_read' FROM ' role '@'localhost';
# see 
SHOW GRANTS FOR ' role '@'localhost';

Set mandatory roles （mandatory role）

The mandatory role is the default role for each account created , No need to set it manually , Mandatory roles cannot be revoke( revoke ) perhaps drop( Delete )

The way 1： modify my.cnf To configure , Set before service startup

[mysqld] 
mandatory_roles='role1,[email protected],[email protected]%.atguigu.com'

The way 2： Runtime settings

# After the system restarts, it still   It works 
SET PERSIST mandatory_roles = 'role1,[email protected],[email protected]%.example.com'; 
# Failure after system restart 
SET GLOBAL mandatory_roles = 'role1,[email protected],[email protected]%.example.com'; 

9. Configuration file usage

9.1 Profile format

# Specific startup options 
[server]
# Specific startup options 
[mysqld]

[mysqld_safe]

[client]

[mysql]

[mysqladmin]

10. Logical architecture

Execution order

1.Mysql Client programs outside the server -> 2. Connection pool -> 3.SQL Interface -> 4. The query cache -> 5. Parser -> 6. Optimizer -> 7. Plug in storage engine -> 8. file system -> 9. The query cache -> 10.sql Interface  

The main body is divided into three layers

adjoining course -> Service layer -> Engine layer

adjoining course

Connect MYSQL Before server , do TCP Connect , Verify the account number and password after three handshakes

The user password is not correct , received Access denied for user error , The client program completes execution

User password authentication passed , From the permission table, you will find out the permission of the account and the connection Association , The following permission judgment logic , All rely on the supervision authority at this time

Mainly create two pools 1） Connection pool  2） Thread pool

Service layer

SQL Interface: SQL Interface

1） Receive the user's SQL command , And returns the result of the query that the user needs . such as SELECT ... FROM It's called SQL Interface

2）MySQL Support DML（ Data operation language ）、DDL（ Data definition language ）、 stored procedure 、 View 、 trigger 、 Self determination

Semantic function, etc SQL Language interface

Parser: Parser

1） In the parser SQL Statement syntax analysis 、 Semantic analysis . take SQL Statements are decomposed into data structures , And put this structure

Pass on to the next step , in the future SQL Statements are passed and processed based on this structure . If you encounter errors in decomposition composition

By mistake , So that's it SQL The statement is unreasonable .

2） stay SQL Commands are validated and parsed by the parser when they are passed to the parser , And create for it Grammar tree , And according to the data word

The dictionary enriches the query syntax tree , Meeting Verify whether the client has permission to execute the query . After creating the syntax tree ,MySQL also

Would be right SQl Query syntax optimization , Query rewriting .

Optimizer: Query optimizer

1） After analysis , Generate before query Implementation plan

2） The plan indicates that those Index to query （ Full search 、 Index search ）, What is the connection order between tables , Finally, call the method provided by the storage engine to perform sweat scrubbing according to the steps of the execution plan , And return the result

3)） use selection - Projection - Connection strategy

Instructions

#mysql8.0 Check whether the execution plan is enabled 
select @@profiling;
#profiling=0 Means closing ,1 Open for indication 
show variables like 'profiling';
# Start the implementation plan 
set profiling=1;

Caches & Buffers： Query cache component

1）MySQL There's some internal maintenance Cache and Buffer, such as Query Cache Used to cache a SELECT Statement execution result , If the corresponding query result can be found in it , Then there is no need to query and parse 、 The whole process of optimization and execution

Cheng , Directly feed back the results to the client

2） The caching mechanism consists of table caching , Record the cache ,key cache , Permission cache

3） Sharing between different clients

4）5.7 Not recommended after , stay 8.0 Delete in

Engine layer

Really responsible MySQL The storage and extraction of data in , At the physical server level Maintain the underlying data and perform operations

# Display storage engine 
show engines;

11.SQL Execute the process

ps: The query cache 8.0 Abandoned , Hit ratio is low , The two statements must be the same , Off by default

The query cache  

Instructions

# Check whether the cache is enabled 
show variable like '%query_cache_type'
# View cache 
show status like'%Qcache%'

Parser

Yes sql Perform analytical analysis

Lexical analysis ： Those are keywords , Those are fields

Syntax analysis ： Whether the grammar meets

Optimizer

It will be determined in the optimizer that SQL Statement execution path , For example, according to Full search , Or according to Index search etc. .

In the query optimizer , Can be divided into Logical query Optimization phase and Physical query Optimization stage .

actuator

View permissions 、 Call the storage engine, such as InnoDB、MyISAM Wait, and then call the storage engine system

Main process

12. Storage engine operation  

A storage engine is a structure that represents a table , Different storage engines represent different structures

View engine

show engines;
# perhaps 
show engines \G;

 

View the default storage engine

show variables like '%storage_engine%'; 
# or 
SELECT @@default_storage_engine;

  Modify the default storage engine

1） Directly modifying

SET DEFAULT_STORAGE_ENGINE=MyISAM;

2） Modify the configuration file

default-storage-engine=MyISAM 
#  Restart the service  
systemctl restart mysqld.service

Create the specified storage engine

CREATE TABLE  Table name ( 
 Create table statement ;
 ) ENGINE =  Storage engine name ;

Modify the storage engine of the table

ALTER TABLE  Table name  ENGINE =  Storage engine name ;
# After modifying the view table structure 
SHOW CREATE TABLE  Table name 

13. Storage engine introduction

InnoDB engine ： Transaction storage engine with foreign key support

advantage ：

        1. Default transactional engine , Designed to handle a large number of short-term transactions , It can ensure the completion and rollback of transactions

        2. In addition to adding and querying , It needs to be updated 、 Delete operation , that , Preference should be given to InnoDB Storage engine

        3. Data file structure          surface .frm    Storage table structure   surface .ibd  Store data and index

        4.InnoDB yes Designed for maximum performance in handling huge amounts of data .

shortcoming ：

        1. contrast MyISAM Storage engine for ,InnoDB The processing efficiency of writing is poor , And it will take up more disk space to             Save data and indexes .

        2.MyISAM Cache index only , Don't cache real data ;InnoDB Not only index but also real data , To save     Seek higher , And memory size has a decisive impact on performance .

MyISAM engine ： The main non transactional storage engine

characteristic ：

1.MyISAM There are a lot of features , Include full text index 、 Compress 、 Space function (GIS) etc. , but MyISAM Unsupported transaction 、 Row level lock 、 Foreign keys , There is no doubt that the defect is Can't recover safely after a crash

2. The advantage is access Fast , There is no requirement for transaction integrity or SELECT、INSERT Mainly applications

3. There is additional constant storage for data statistics . so count(*) The query efficiency is very high

4. Table structure surface .frm Storage table structure           surface .MyD  Store the data         surface .MYI Storage index

application : Read only applications or read-only businesses

Archive engine ： For data archiving

Blackhole engine ： Discard write operation , The read operation will return empty content

CSV engine ： When storing data , Separate data items with commas

Memory engine ： Table in memory

Federated engine ： Access remote tables

Merge engine ： Manage multiple MyISAM A collection of tables made up of tables

NDB engine ：MySQL Cluster specific storage engine