Programmer Help

1, Database operation 1) Select and create database syntax: use database name The rule of the use command is to switch if the corresponding database exists, and create if it does not exist 2) Deletion of database db.dropDatabase() 3) View databases with permissions show dbs or show databases Note: when you use the use com ...

1. Specific contents 1.1 concept JDBC (Java DataBase Connectivity) is a java database connection. In other words, it uses the Java language to operate the database. It turns out that we operate the database by using SQL statements on the console, and JDBC sends SQL statements to the database in Java language. JDBC (Java Data Base Connecti ...

The transaction message of rocketmq is used as a solution to distributed transactions on some occasions. Today, let's analyze the transaction message of rocketmq catalogue 1. Transaction message flow process 2. The producer sends a transaction message (half message) 3. The broker handles the half message 4. The producer executes a local tr ...

catalogue 1, overlay 1. AUFS and overlay / overlay 2 2. overlay structure 3. Joint mount 2, Written by dockerfile 1. Dockerfile structure consists of four parts 2. CMD and entrypoint 3. Write dockerfile 4. dockerfile optimization Optimization scheme summary Building nginx images docker image hierarchy Difference between CMD and EN ...

Tip: after the article is written, the directory can be generated automatically. Please refer to the help document on the right for how to generate it preface This article is the author's study notes. It records in detail the author's understanding of SQL digital injection, and also introduces the complete process of using union joint q ...

1, Concept of distributed transaction 1. What is a transaction A transaction can be regarded as a big activity. It consists of different small activities. These activities either succeed or fail. 2. Local affairs Four characteristics of database transactions ACID: A(Atomic):   Atomicity  ， All operations constituting a transact ...

Redis Redis is short for Remote Dictionary Service; It is also a Remote Dictionary Service; Redis is a memory database, KV database and data structure database; Redis is widely used, such as Twitter, Blizzard Entertainment, Github, Stack Overflow, Tencent, Alibaba, JD, Huawei, Sina Weibo, etc. many small and medium-sized companies are also u ...

preface This article continues to introduce the main process and main details of memory flush on hregon, and how cacheflush handles flush requests. How does cacheflush handle flush requests Through the introduction of how to initialize cacheflush, we know that there are two queues and collections that store flush requests and their h ...

It is often said that reading source code is the only way for every excellent development engineer, but in the face of complex systems like TiDB, source code reading is a very huge project. For some TiDB users, starting from their daily problems, reading the source code is a good entry point. Therefore, we planned a series of articles on readin ...

Last time I wrote about JPA, let's talk about Spring Data JPA Spring Data JPA is a set of JPA application framework encapsulated by spring based on ORM framework and JPA specification. Developers can use very simple code to access and operate the database. In daily use, Spring Data JPA development frees us from the operation of Dao layer, and ...