Index analysis of union primary key (Union index) in SQL Server (MySql)

Recently, someone asked this question in the interview. Before that, they had not studied the specific use logic of the joint index, consulted several articles, and came to some conclusions after testing Test environment: SQL Server 2008 R2 The test results are similar to the query mechanism of MySql joint index. We can think that MySql is the ...

Posted by kathas on Fri, 01 May 2020 08:02:06 +0200

Issue 03: column non empty and self increasing

There are many attributes of fields in MySQL, and the impact on performance can be large or small, so it's necessary to explore the attributes. 1, NULL / NOT NULL For external programs, NULL is an unknown, imprecise, and indescribable value. Therefore, it is clearly stipulated in the development specifications of many companies that it must be ...

Posted by dayo on Wed, 29 Apr 2020 10:59:26 +0200

Case analysis: python operation database project

According to an example of a project, this paper records and shares the process and relevant settings of python's displaying the content of database to the program interface, and explores the usage of python's operating database. Main contents to be shared: 1. Displays the database contents. 2. Modify database content. 3. The table control spec ...

Posted by andrewgk on Wed, 29 Apr 2020 08:50:53 +0200

Installation and configuration of big data platform CDH5.16.2

Tags (space separated): building big data platform 1: Environment initialization 2: Installation of CDH5.16.2 1.1: introduction to system environment System: RHEL7.7X64 cat /etc/hosts --- 192.168.100.21 rhel01.flyfish 192.168.100.22 rhel02.flyfish 192.168.100.23 rhel03.flyfish 192.168.100.24 rhel04.flyfish ----- Only three ...

Posted by Berone on Sun, 26 Apr 2020 17:47:28 +0200

Talk about my SqlConnection of canal

order This paper focuses on my SQL connection of canal ErosaConnection canal-1.1.4/parse/src/main/java/com/alibaba/otter/canal/parse/inbound/ErosaConnection.java public interface ErosaConnection { public void connect() throws IOException; public void reconnect() throws IOException; public void disconnect() throws IOException; ...

Posted by DuFF on Sat, 25 Apr 2020 16:47:49 +0200

Dockerfile image making practice

If you don't know what Dockerfile is, you can check my previous blog:https://blog.51cto.com/14557905/2489466Dockerfile image production practiceThree steps for Dockerfile to create image1, Making sshd image1. Write Dockerfile file [root@docker sshd]# vim Dockerfile #base image FROM centos:7 #User information MAINTAINER this is sshd project #B ...

Posted by keigowei on Fri, 24 Apr 2020 17:20:41 +0200

Oracle (Basic Grammar)

1. Functions 1.1 case conversion function function describe LOWER() All lowercase UPPER() uppercase INITCAP() title case 1.2 String Operating Functions function describe concat() Split String Substr (field, startIndex,endIndex) substr length() String Length Instr (field,'character') Location index where specified characte ...

Posted by speedyslow on Thu, 23 Apr 2020 05:04:22 +0200

Mybatis framework -- mybatis reverse engineering

< center > mybatis reverse engineering < / center > ​ The purpose of reverse engineering is to reduce our development time. The so-called Mybatis reverse engineering is that Mybatis will automatically generate pojo, mapper and mapper.xml according to the data table we have designed. The next step is the project construction proces ...

Posted by FastLaneHosting on Wed, 22 Apr 2020 18:14:12 +0200

SonarQube installation configuration

thanks Download sonarqube-6.4 Download SonarQube Scanner mysql adds a database named sonar and the user sonarqube@sonarqube Unzip SonarQube and modify the database configuration and user configuration of the configuration file [root@localhost pig]# vim sonarqube-6.4/conf/sonar.properties # Configure database user na ...

Posted by gfoot on Wed, 22 Apr 2020 17:16:17 +0200

Talk about my SQL detecting time task of canal

order This paper focuses on my SQL detecting time task of canal MysqlDetectingTimeTask canal-1.1.4/parse/src/main/java/com/alibaba/otter/canal/parse/inbound/mysql/MysqlEventParser.java class MysqlDetectingTimeTask extends TimerTask { private boolean reconnect = false; private MysqlConnection mysqlConnection; ...

Posted by TheAngst on Mon, 20 Apr 2020 18:04:02 +0200