• Lock contention in MySQL


    Lock is a mechanism for computer to coordinate multiple processes or threads to access a resource concurrently!No matter MyISAM or InnoDB, lock contention will occur. In theAll kinds of locks in MySQLIn this article, we have talked about how to view table lock and row lock contention ======================================================================= 1. Table locking SHOW STATUS LIKE ‘table%’; […]

  • The principle of transaction persistence in MySQL


    preface When it comes to database transactions, it’s easy for you to have a lot of knowledge about transactions in your mind, such as the acid characteristics of transactions, isolation levels, problems solved (dirty read, non repeatable read, magic read), etc. but few people really know how these characteristics of transactions are realized, and why […]

  • Oracle foundation 2: three paradigms of Oracle view, user management, sequence, DML, transaction, index and database design


    1、 View 1. View, also known as virtual table, does not occupy physical space. This is also a relative concept, because the definition statement of view itself should be stored in the data dictionary. Views have only logical definitions.Every time you use it, you just re execute SQL。2. Views are obtained from one or more […]

  • Programming architecture (08): spring.mvc.boot framework


    Source code:GitHub. Click here || Gitee. Click here 1、 Spring framework 1. Framework overview Spring is an open source framework. One of the main advantages of the framework is its layered architecture, which allows users to choose which component to use and provides an integrated framework for J2EE application development. Spring uses basic JavaBeans to […]

  • Analysis of MySQL deadlock (intermediate)


    InnoDB actively detects the deadlock and rolls back a waiting transaction. The question is, how does InnoDB detect deadlocks?The intuitive method is that when two transactions wait for each other, when the waiting time of one transaction exceeds a set threshold, one transaction is rolled back, and the other transaction can continue to execute. This […]

  • Three proxy patterns in Java


    First: static proxy code implementation 1. Design interface public interface IUserDao { void save(); } 2. Implement the interface public class UserDao implements IUserDao { 3. Agency The interface must be implemented public class UserDaoProxy implements IUserDao { 4. Testing public class App { The second one is JDK dynamic proxy code implementation 1. Design […]

  • Hard core! Eight pictures to understand the end-to-end processing semantics of Flink exactly once


    Flink There are three locations in Flink that need end-to-end precise processing at one time Source side: when data enters Flink from the previous stage, it needs to ensure that the message is consumed accurately at one time. Internal side of FlinkWe have learned that by using checkpoint mechanism, the state can be saved to […]

  • Mybatis [2.2] – some questions about creating sqlsession source code analysis?


    The code is placed directly in GitHub warehouse【 https://github.com/Damaer/Myb… 】It can be run directly, so it doesn’t take up space. [TOC] 1. Why don’t we need to close the stream when we use SQL session factory builder? Let’s look at our code: public class StudentDaoImpl implements IStudentDao { private SqlSession sqlSession; public void insertStu(Student student) […]

  • Meet Redux saga for the first time


    Redus-sagaRedux is a middleware of Redux, which is mainly used to deal with the side effects of Redux applications simply and elegantly. It can do this mainly because it uses a syntax in ES6:Generator. Using generator, you can write asynchronous code just like writing synchronous code, which makes it easier to test. Before we go […]

  • Mybatis [2.3] – must mybatis use commit to successfully modify data?


    The code is placed directly in GitHub warehouse【 https://github.com/Damaer/Myb… 】Mybatis-02 can be run directly, so it doesn’t take up space. Why do we sometimes modify the database successfully without using commit? [TOC] 1. From the database level, in fact, it mainly depends on what “storage engine” you use For example, the following code uses the […]

  • Oracle (day 3)


    1、 Delete: a DML statement. Delete the data with specified conditions in the database Delete from table name where a = B( Conditional deletion) Delete from table name; Delete the data of all rows. You cannot delete the value of a column. After executing the statement, you need to commit to reflect it in the […]

  • 12 pictures show you a thorough understanding of distributed transactions!!


    Write on the front The background of writing this article is that a small partner who has a good relationship with me went to a large Internet company for an interview. The interviewer asked him a question about distributed transactions. Unfortunately, he didn’t really have a deep understanding of distributed transactions, and the interview result […]