Day128: MySQL advanced:

itread01 2021-01-22 01:17:09
day128 day mysql advanced


1. Introduce and install

2. Basic management

2.1 User management

2.2 License management

2.3 Connection management

2.4 Configuration Management

3.MySQL The architecture of


5. Index and execution plan

1. Introduce and install

1.1 Database classification

RDBMS( Relational databases ):Relational Database Management System

On behalf of the product :Oracle  MySQL  MSSQL PG 

NoSQL( Non relational database ):Not Only SQL

Representative works :MongoDB  Redis  ES

NewSQL( For all kinds of new extensible packages / Short for high performance database )

Representative works :spanner  PolarDB(X)  TDSQL  TiDB  gaussian

1.2 MySQL Branch




4. Cloud vendors

1.3 MySQL Get

1.4 MySQL Install

# 1. Unloading [[email protected] opt]# tar xf mysql-8.0.20-linux-glibc2.12-x86_64.tar.xz# 2. Soft link ln -s /opt/mysql-8.0.20-linux-glibc2.12-x86_64 /usr/local/mysql # 3. Modify environment variables vim /etc/profile Add the following export PATH=/usr/local/mysql/bin:$PATH source /etc/profile# 4. Create users Catalog Configuration file [[email protected] mysql]# useradd mysql[[email protected] mysql]# mkdir -p /data/3306/data[[email protected] mysql]# chown -R mysql.mysql /data[[email protected] mysql]# vim /etc/my.cnf[mysqld]user=mysqlbasedir=/usr/local/mysqldatadir=/data/3306/datasocket=/tmp/mysql.sock[mysql]socket=/tmp/mysql.sock# 5. Initialization data If there is no configuration file : mysqld --initialize-insecure --user=mysql --basedir=/usr/local/mysql --datadir=/data/3306/data If there is a configuration file : [[email protected] data]# mysqld --initialize-insecure # 6. Ready to start the script [[email protected] ~]# cp /usr/local/mysql/support-files/mysql.server /etc/init.d/mysqld[[email protected] ~]# /etc/init.d/mysqld stopShutting down MySQL... SUCCESS! [[email protected] ~]# /etc/init.d/mysqld startStarting MySQL.. SUCCESS! [[email protected] ~]# /etc/init.d/mysqld restartShutting down MySQL.. SUCCESS! Starting MySQL.. SUCCESS! [[email protected] ~]# /etc/init.d/mysqld statusSUCCESS! MySQL running (12134)

2. Basic management

2.1 User management

2.1.1 effect

1. To log in to MySQL

2. To manage MySQL thing [ps: What is MySQL thing ??]

2.1.2 Define

Grammar : User name @' White list '

What is a white list ??  answer :IP Address range  

Common forms :

[email protected]'%'
[email protected]'localhost'
[email protected]'10.0.0.%'
[email protected]''

2.1.3 Manage users

1. Query users


-- Query users mysql> select user,host ,authentication_string ,plugin from mysql.user;+------------------+-----------+------------------------------------------------------------------------+-----------------------+| user | host | authentication_string | plugin |+------------------+-----------+------------------------------------------------------------------------+-----------------------+| mysql.infoschema | localhost | $A$005$THISISACOMBINATIONOFINVALIDSALTANDPASSWORDTHATMUSTNEVERBRBEUSED | caching_sha2_password || mysql.session | localhost | $A$005$THISISACOMBINATIONOFINVALIDSALTANDPASSWORDTHATMUSTNEVERBRBEUSED | caching_sha2_password || mysql.sys | localhost | $A$005$THISISACOMBINATIONOFINVALIDSALTANDPASSWORDTHATMUSTNEVERBRBEUSED | caching_sha2_password || root | localhost | | caching_sha2_password |+------------------+-----------+------------------------------------------------------------------------+-----------------------+


Be careful : plugin, Encryption plug-in , stay 8.0 And then we did an upgrade ,caching_sha2_password, The safety has increased .

It will cause many old client programs to be unable to connect to MySQL. The earlier version was mysql_native_password.

2. Create users / Modify user / Delete user

-- Create users mysql> create user [email protected]'10.0.0.%' identified by '123';mysql> create user [email protected]'10.0.0.%' identified with mysql_native_password by '123';-- Modify user mysql> alter user [email protected]'10.0.0.%' identified with mysql_native_password by '123';mysql> alter user [email protected]'10.0.0.%' account lock;mysql> alter user [email protected]'10.0.0.%' account unlock;-- Delete user mysql> drop user [email protected]'10.0.0.%';

Be careful : 8.0 After that , Users can only be created before authorization .

2.2 License management

2.2.1 List of licenses

mysql> show privileges;

The most common license :

1.ALL ? It doesn't contain grant option ,insert ,update ,delete

2.2.2 Licensing and recycling rights

-- Authorization mysql> grant all on *.* to [email protected]'10.0.0.%';-- Inquiry permission mysql> show grants for [email protected]'10.0.0.%';-- Recycling licenses mysql> revoke drop on *.* from [email protected]'10.0.0.%' ;

As for the scope of the license :

*.* : All tables under all libraries

luffy.*: All tables in a single library

luffy.user: Single table

2.3 Connection management

2.3.1 socket File connection

-- Premise : It needs to be built in advance localhost Users of the white list [[email protected] ~]# mysql -uroot -p -S /tmp/mysql.sock

2.3.2 TCP/IP The way

-- Premise You need to log in to the client IP Join the white list [[email protected] ~]# mysql -uroot -p123 -h -P3306

2.4 Configuration Management

2.4.1 Offline configuration

-- Configure file application order [[email protected] ~]# mysqld --help --verbose |grep my.cnf/etc/my.cnf ---> /etc/mysql/my.cnf ---> /usr/local/mysql/etc/my.cnf --> ~/.my.cnf 
-- Configure file structure [[email protected] ~]# cat /etc/my.cnf

Be careful : Modify configuration file , Restart the database .

2.4.2 Online configuration

-- Modify through special configuration command .mysql> set global innodb_buffer_pool_size=16777216;
-- View all arguments that can be configured online show variables show variables like '%date%';

3.MySQL The architecture of

Not much , Directly above .

1. Connection layer

The wire layer has three functions :

1. Provide connection protocol : Socket Archives ,TCP/IP

2. Verify user identity / Authorization Form .

3. The connection layer provides a connection with sql The thread of layer interaction

2.SQL Layer

SQL There are six layers :

1. From the receiving layer sql Sentence

2. Verification sql Sentence syntax

3. Verification sql The semantics of a sentence (DDL,DQL,DML,DCL)

4. Parser : analysis sql Sentence , Generate execution plan

5. Optimizer : Choose the best one from the execution plan

Optimization ???? Optimization ( Logic optimization , Physical optimization ( Indexes )

6. Actuators : Execute the selected SQL Plan

1. Create threads that interact with the storage engine layer

2. What will be carried out sql Statement to the storage engine layer

3.Engine Layer

effect : Responsible for interacting with disks


4.1 What is SQL?

General language for relational databases . Structured query language .[ps: What is structured query language ?]


Commonly used SQL_MODE Arguments :[ps:SQL_MODE Detailed explanation ]

mysql> select @@sql_mode;+-----------------------------------------------------------------------------------------------------------------------+| @@sql_mode |+-----------------------------------------------------------------------------------------------------------------------+| ONLY_FULL_GROUP_BY,STRICT_TRANS_TABLES,NO_ZERO_IN_DATE,NO_ZERO_DATE,ERROR_FOR_DIVISION_BY_ZERO,NO_ENGINE_SUBSTITUTION |+-----------------------------------------------------------------------------------------------------------------------+

Emphasis :  ONLY_FULL_GROUP_BY ,5.7 Version new features .

4.3 Data type

Pay special attention to :

char(10) Fixed length

varchar(10) Lengthen

Other detailed data types :[ps:MySQL Data type in ]

4.4 Character set

utf8 Save up to three byte characters

utf8mb4 Save up to four byte characters [emoji expression ]

4.5 SQL Species

DDL : Data definition language

DML : Data operation language

What is DDL( Data definition language ?), What is DML( Data operation language ?):[ps:DDL and DML The definition of ]

4.6 DDL Application specification of

4.6.1 To the library (Database) The operation of

Ku :
create database

drop database

alter database

Regulate :
a. The production system is disabled drop operation

b. Do not use system reserved characters for library names , Don't use capital letters , Don't start with a number .

c. To build a library is to explicitly set the character set .

4.6.2 Antithetical table (Table) The operation of

create table

Regulate :

Do not use system reserved characters for table names , Don't use capital letters , Don't start with a number .ob_user; Don't exceed 18 Character .

Data type :

Appropriate Short Enough

Be careful :

Each table should have a primary key .

Each column is as non empty as possible , Or set a default value

Each column should be annotated .

Storage engine usage InnoDB Character set utf8mb4

alter table

Main uses :

New column

Delete column

Suo Yin

Delete index

This type

About alter table One more thing to know :

8.0 before :Online DDL It needs to be done during the business period . Or use PT-OSC.

8.0 After that : New columns can be added directly .

drop table It's not necessary to use .

4.7 About DDL/DML and MySQL Problems in the implementation phase

prepare  MDL X Block all DML Write DDL

exec      S Demote shared lock Don't block DML , Blocking DDL

commit  MDL X Block all DML Write DDL

5. Index and execution plan

5.1 What is index ?

It's like a catalog in a book . Optimize the query (select update  delete)

5.2 Index type

BTREE *****

RTREE( Spatial data index )

HASH( Hash index )

FTEXT( Full-text index )

5.3 BTREE Structural understanding

b+tree(b*tree) --> Enhanced version

5.4 MySQL How to apply BTREE?

5.4.1 Cluster index

1. What is clustering index ?

InnoDB in , Table data file itself is press B+Tree An index structure of an organization , Clustering index is to construct a cluster according to the primary key of each table B+ Tree , At the same time, the leaf node stores the row record data of the whole table , The leaf node of a clustered index is also called a data page . This feature determines that the data in the index organization table is also a part of the index ;

2. The construction condition of clustering index ?

Primary Key / Unique+not null / RowID

3. The construction details of clustering index ?

Leaf node (Leaf): When entering data , It will follow the logical order of clustering index , Stored in physically continuous multiple data pages . So we have leaf nodes . And store the two-way index of adjacent leaf nodes .
Branch nodes (No-Leaf): Select the leaf node ID The scope of + Indicators .
The root node (ROOT) : No-leaf Node's ID Scope + Indicators

4. The optimization effect of clustering index ?

Through ID When columns are used as query criteria , It will optimize .

5.4.2 Secondary index




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