MySQL development practice summary (I)

1、 Determine the version online

①、 The current mainstream is 5.7.X and 8.X edition ,8.x Version optimization , Better read / write performance .

2、 Installation mode ：

①、 The simplest test uses , Download a package directly from the official website , Follow the tutorial to install the configuration , have access to Docker To install and use , It is also faster and more convenient , Open the port after deployment on the test machine , The connection test can be used .

②、 Production use ： The simplest active / standby or read / write separation libraries can be built on different machines , And configure some monitoring scripts , Hang the tray separately SSD Keep it stable ,binlog Specify the corresponding save time expiration cleanup , You can also buy cloud services RDS database , Select the corresponding instance specification , With complete monitoring , Migrating data , Expansion specification , Operation and maintenance are quite convenient , Optimization parameters , General enterprises are using , Business uses direct connections vip Floating address , Can be safe .

③、 Disaster recovery transformation ： Ensure highly available disaster recovery architecture for databases , Cloud services are generally purchased in the same Region Two machines , Large scale project guarantee disaster recovery architecture , Usually in different Region There are also examples of transformation , Span AZ disaster , One main, one standby and one cascade , For example, both Beijing No. 4 and Beijing No. 1 have , Then give a float IP, Even on one side AZ Hanging up does not affect business stability .

3、 Library table permissions

①、 General maximum authority Root All are DBA be responsible for , For some businesses, create libraries and tables and separately assign certain reasonable and controllable permissions ,grant Grant permissions to tables , For some, the timer and partition table permissions are allocated separately , The master is copied to a separate designated account , You can specify a network segment and specify IP To achieve replication , Prevent operation with too large permission .

②、 For temporary business needs , You can specify a temporary account number , Then you can delete it after you use it , It is applicable to modifying business database passwords and special businesses .

③、 port 、 password 、 Account compliance , No default 3306, Pay attention to network segment VPC Divide .

4、 Build a table to regulate

①、 Build table SQL Code warehouse archiving , The create table field specifies the description , The primary key depends on the business scenario , Select auto increment 、UUID、 Joint multi field primary key , although innodb A self incrementing primary key can specify its location , The index nodes can be connected in ascending order ,B+ The order of the number of inodes is always , However, it is not recommended if there are too many modifications and deletions , Design according to the actual scene , The following tables are also troublesome .

②、 Properly evaluate business scenarios and build appropriate indexes , Useless indexes will cause the write data to be indexed too slowly, which will affect the speed , Joint indexing is preferred , Override index is preferred .

③、 Evaluate useless indexes , Delete if you can , No waste of necessary storage space and write speed .

④、 Create a table to specify the data creation time, update time, and logical deletion of some business scenarios .

5、 Data cleaning

①、 General business data will be saved for a certain period of time , Delete data according to the duration , Remember to defragment the tablespace , Generally delete data 、 There will be some fragments in the updated data , Cannot fully utilize , Lead to mysql When writing data, there is no full page space , Waste space .

②、 Time series data can consider partition table , Such as according to the time Range The way of division , By day or by month , The table is transformed into a partition table , Pre build future tables , Regularly delete the previous partition table , Can completely solve the problem of table space expansion , Based on distributed timed task time , For deletion failure or partition establishment failure, service alarms can be sent to meet the stability , Use es It is also a way of dividing by day or month .

③、 It can be implemented based on certain rules , And then directly after the expiration drop Physical tables are also more convenient , Every day and every month , In business, it is more convenient to have a vertical database .

④、 Delete library table data drop、 Delete some data delete、 Clear the table data directly truncate.

⑤、 You can also use mysql Of event Timer , But it's not controllable , In case of abnormal conditions, the priority cannot be given .

⑥、 The data backup , have access to xxl-job Of shell Execute the backup script regularly , To different components , If OBS Bucket or some object storage medium , have access to Flink CDC2.0 To synchronize to other databases .

6、 Sub database and sub table

①、 Vertical sub database ： According to different business Split different database Easy to expand , Different database instances can be deployed Effectively reduce database pressure .

②、 Vertical sub table ： Split large table fields 、 Split into small tables 、 Reduce single table fields .

③、 Horizontal sub table ： according to The data field module is used to split different databases and tables , Make single table naming rules , If different types are spliced to form a complete table , Then the business side reads and writes the specified table , Yes hash modulus , For the specified account number %20, Here take 20 Zhang Zibiao , Then it's divided into 0-19, The data range is estimated by table , Then write to different libraries , Of course, you can hash Take the mold and divide the warehouse , Then divide the sub table in the range .

④、 Data migration can use some vendors' cloud services , Or double write migration , Interface connects different databases grafana Monitor and observe .

7、 Business time storage

①、 Use it directly point Time stamp in seconds of 、 Millisecond time , With long Type storage .

②、datetime String mode .

8、 Necessary parameter tuning

①、 For example, the maximum number of connections innodb-buffer-pool-size、max-connections、log-bin Maximum time 、 Maximum packet size 、 Server character set and characters , The maximum number of connections is evaluated according to the number of database instance connections , Generally, the number of business parties' database connection pools and cluster specifications are reasonably set .

②、 Specify the longest life cycle for the corresponding database connection pool , Expired release , Then create a new , To a certain extent, reduce the server connection memory surge scenario , The database connection pool connects with a certain monitoring platform to collect data , Observe the situation and adjust .

③、 Error log 、 Binary log 、 Relay log configuration .

9、 Database driven selection

①、 General choice mysql drive ,8.x Driver compatibility 5.7.x Database version .

<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <version>8.0.29</version>
</dependency>

<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <version>5.1.49</version>
</dependency>

②、 consider License Safe to use , yes mysql An open source branch of .

<dependency>
    <groupId>org.mariadb.jdbc</groupId>
    <artifactId>mariadb-java-client</artifactId>
    <version>3.0.5</version>
</dependency>

10、 Database time and encoding and opening SSL

①、 Database time zone view ：show variables like '%time_zone%';

②、 Set up set time_zone = '+8:00';

③、 View the database code ：show variables like "char%";

④、 No configuration by default SSL Certificate location , Use in the drive useSsl=false, Configure the certificate to enable ;

11、ORM Frame selection

①、MyBatis、MyBatisPlus Single table multi table dynamic SQL, It is suggested to encapsulate , It is a big project to change and upgrade .

②、Hibernate encapsulation BaseDao, Other businesses develop their own XXDao, Bottom layer to use BaseDao Business methods in , Follow up design to upgrade the open source package , Change the corresponding API The smallest is the smallest , It's more convenient , It is also convenient to maintain the platform layer .

③、JdbcTemplate/Jdbc To complete the original precompile SQL.

12、 monitor 、 Deadlock 、 Business 、 Connect

①、information_schema library

 ②、sys library

Positioning lock waiting

show processlist【 Check the connection Query】

①、select * from information_schema.innodb_lock_waits;

Positioning lock

①、select * from information_schema.innodb_locks;

Locate transactions

①、select trx_id,trx_started,trx_requested_lock_id,trx_query,trx_mysql_thread_id from information_schema.innodb_trx;

The result is two transactions ,MySQL Transaction thread id by 38 and 41, Very intuitive to see 41 It is our delete Business , By 38 lock

Locate threads

①、select * from performance_schema.threads where processlist_id=38;

It turns out that MySQL Transaction thread 38 Corresponding server thread 63.

Positioning and locking SQL

select * from performance_schema.events_statements_current where thread_id=63;

  You can query relevant information and analyze problems from these databases .

I hope to be right mysql There is a clear knowledge network in the development process , Constantly improve the knowledge system , Provide solutions that are more suitable for business scenarios .