Programmer Group

#Author introductionJiang Pengcheng, Suzhou wandianzhang Software Technology Co., LtdprefaceCloudCanal recently provided the ability to build a wide table with custom code. We participated in the internal test of this feature for the first time, and it has been put into production and operated stably. See the official documents for the developm ...

1. Method 1.1 general In actual development, we need to write a large number of logic codes, which is bound to involve repeated requirements. For example, for the maximum values of 10 and 20 and the maximum values of 11 and 22, the logic code for comparison needs to be written twice. If the logic code for comparison is put into the method, it ...

In microservices, for high availability, the same service is often deployed in cluster mode, that is, there are several same services at the same time, and the core of gray level is routing, which calls the target service line through our specific strategy 1 Introduction to gray routing Grayscale publishing (also known as Canary Publ ...

##Database connection pool       The code logic in the previous section is equivalent to opening a restaurant, recruiting a waiter connection to connect to the database service when the guest comes, and firing the close when the guest leaves   So we should recruit a few employees. It's a great waste of resources   &n ...

Subquery refers to a query in which one query statement is nested inside another query statement. This feature has been introduced since MySQL 4.1. The use of SQL sub query greatly enhances the ability of SELECT query, because many times the query needs to obtain data from the result set, or calculate a data result from the same table, an ...

This note is the learning content of Alibaba cloud Tianchi Longzhu plan SQL training camp. The link is: https://tianchi.aliyun.com/specials/promotion/aicampsql preface This note is the learning content of Alibaba cloud Tianchi Longzhu plan SQL training camp. The link is: https://tianchi.aliyun.com/specials/promotion/aicampsql 1. Part ...

1. Overview and principle of MapReduce MapReduce is a distributed computing model   MapReduce runs distributed and consists of two stages: Map and reduce. The Map stage is an independent program, with many nodes running at the same time, and each node processes part of the data. The reduce phase is an independent program, with many nodes ...

catalogue 1, Concept of transaction 2, Operating transaction commands in MySQL database   2.1. Write the test SQL script as follows: 2.1. Start transaction 2.2. Commit 2.3. Rollback 3, Using transactions in JDBC 3.1. JDBC transaction example   3.2. Set transaction rollback point 4, Four characteristics of transaction (ACID) ...

2021SC@SDUSC 1, Brief description Snapshot is a function supported by many storage systems and database systems. A snapshot is the image of a whole file system or a directory at a certain time. 2, Basic principle The simplest and crudest way to realize data file mirroring is to lock the copy (the reason for locking is that the data obtai ...

Author: Zhang Lianzhuang, PostgreSQL R & D EngineerHe has been engaged in the development of PostgreSQL database kernel for many years and has a very in-depth research on citus.Recovering lost data quickly is an important functional requirement of the database. It is generally recommended to use the tools recommended by the official. For op ...