How to add fields to mysql large tables without stopping

Adding fields to a table of ten million or more levels in MySQL has always been a headache. In this case, how to deal with it? This paper uses three common scenarios to illustrate the case. 1. Environmental preparation Database version: 5.7.25-28 (Percona branch) Server configuration: three centos 7 virtual machines with 2CPU 2G memory Database ...

Posted by romilbm on Fri, 19 Jun 2020 23:20:57 -0700

boost.asio The implementation of std::bind on the asynchronous echo server side of

Since C++11, it has provided many traversal tools. Some tools in the boost library have also entered the C + + standard library. Boost, as a "quasi" standard library, is also the knowledge and skills that C + + needs to master as much as possible. Now we use std::bind to realize the asynchrono ...

Posted by -Mike- on Mon, 15 Jun 2020 21:35:17 -0700

Wechat applet socket.io Instant messaging development (based on E-chat SDK)

1. Background: Because wechat applets need to be developed in light weight, cross platform and short development time, many companies regard applets as the first APP for business presentation. The communication part of E-chat client core SDK has been adapted to wechat applet platform. Let's share the ideas and methods in the adaptation process. ...

Posted by gskaruz on Sat, 13 Jun 2020 23:47:43 -0700

Python implementation of multiplexing TCP LAN file transmission based on socket

Basic information of LAN transmission 1. What is Io? ⦁ definition ⦁ blocking IO ⦁ non blocking IO 2.IO multiplexing definition select specific usage 3. Realize the file transmission of multiplex LAN server.py client.py FileOperation.py matters needing attention Operation effect 1. What is ...

Posted by steelerman99 on Sat, 13 Jun 2020 21:27:21 -0700

rsync+crond for scheduled backup

rsync introduction rsync is called remote synchronization in English. From the name of the software, it can be seen that rsync can make the data between the local and remote hosts copy the synchronous image and remote backup quickly. This function is similar to the scp command with ssh, but it is bet ...

Posted by vivianp79 on Fri, 12 Jun 2020 22:03:41 -0700

CentOS (rsync+crond for scheduled backup)

1, rsync introductionrsync is called remote synchronization in English. From the name of the software, it can be seen that rsync can make the data between the local and remote hosts copy the synchronous image and remote backup quickly. This function is similar to the scp command with ssh, but it is bett ...

Posted by christine75 on Fri, 12 Jun 2020 21:00:24 -0700

Note: Chapter 9 of High Performance Python

This chapter is about parallel computing, accounting for more than 60 pages. After reading it, we have to straighten out and digest this big lump of things. 1. Using Monte Carlo simulation to estimate pi. The logic is simple: put the needle in the unit square of the coordinate system, calculate the proportion of the needle falling in the 1 / 4 ...

Posted by dunnsearch on Thu, 11 Jun 2020 20:43:15 -0700

Zookeeper implements service registration / discovery

what that? Zookeeper is frequently used in distributed development, but many frameworks encapsulate it. Beginners may not understand its working principle well. This article demonstrates the simple demo of using zookeeper to realize service registration and service discovery, hoping to achieve the effect of attracting valuable ideas; why need ...

Posted by phpdev12 on Mon, 08 Jun 2020 21:42:03 -0700

Simple command line implementation based on STM32

Simple command line implementation based on STM32 Hi,long time no see. I looked at the atomic usmart and lwip official shell, and found that they all had one thing in common. After identifying the first command, I began to find the callback, and did not count the argc and argv. There are also many peo ...

Posted by warrenk on Sun, 07 Jun 2020 19:42:38 -0700

What's new in Java 13

Java 13 It has been officially released on September 17, 2019, Download Java 13 here Or here openJDK archived . Java 13 features. JEP 350: dynamic CDS Archive JEP 351: ZGC: uncommit unused memory JEP 353: re implement the old socket API JEP 354: switch expression (Preview) (developer ...

Posted by philwong on Thu, 04 Jun 2020 22:56:49 -0700