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Index naming conventions: Single valued index, idx is recommended_ All lowercase letters begin with. For example: alter table t1 add key idx_r1(r1)； Combined index, DX is recommended_ multi_ Start with all lowercase letters. For example: alter table t1 add key idx_multi_1(r1,r2,r3) ; Unique index, recommended in udx_ Is the beginning, a ...

Time attribute Flink supports three time concepts related to stream data processing: Processing Time, Event Time and Ingestion Time. Blink SQL only supports two time types: Event Time and Processing Time: Event Time: Event Time (usually the most original creation time of data). Event Time must be the data provided in the data store.Process ...

Why do I need a thread pool We know that the common way to create a thread is new Thread(), and every time new Thread(), a thread will be re created, and the creation and destruction of threads will take time, which will not only consume system resources, but also reduce the stability of the system. In jdk1 There is an executor in the JUC pack ...

catalogue introduce background Indexes Default index How to create an index Different types of indexes in MongoDB 1. Single field index  2. Composite index 3. Multi key index 4. Text index MongoDB index properties 1. Unique 2. Sparse 3. Partial index 4. TTL index Some key points 1. getIndexes() 2. dropIndex() 3. dropInd ...

1, First look at the renderings: After clicking login, if the password is correct, it will directly jump to the success interface I First create a user table in the database Table name: user Save several users: The preparation is almost done. Start writing code Open the project of building a successful SSM environment in our previous artic ...

brief introduction What does MySQL master-slave replication do 1.MySQL master-slave replication does not affect the normal operation of the business during the table locking process. The master database is responsible for writing and the slave database is responsible for reading. In this way, the master database can also lock the table and ...

1, Environment construction   create maven web project mybatis01 and add maven dependencies as follows. <dependency> <groupid>org.mybatis</groupid> <artifactid>mybatis</artifactid> <version>3.4.6</version> </dependency> <dependency> <groupid>mysql</groupid ...

12. Dynamic SQL What is dynamic SQL? Dynamic SQL is to generate different SQL statements according to different conditions Dynamic SQL is one of the powerful features of MyBatis. If you have used JDBC or other similar frameworks, you should be able to understand how painful it is to splice SQL statements according to different conditions. Fo ...

preface: phpMyAdmin is a MySQL database management tool based on PHP and built on the server in Web mode. It enables managers to manage MySQL database through web interface. Because of its simple and easy to operate graphical interface based on Web, it is loved by website managers. When we get the MySQL account and password through other ...

Master-slave architecture Create one master and two slave folders. mkdir master slave1 slave2 Copy etc / redis / redis The conf files are stored in three folders. cp /etc/redis/redis.conf /master cp /etc/redis/redis.conf /slave1 cp /etc/redis/redis.conf /slave2 Modify the configuration in turn Set the master port number to 7000, slave1 p ...