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  How does MySQL handle DROP TABLE

A few days ago, when executing DROP TABLE in MySQL, all processes including DDL and DML were hung until DROP TABLE was completed. I am confused about this phenomenon. I have reviewed the source codes of MySQL to check how MySQL internally handle DROP TABLE. When user trigger DROP TABLE command: ########################MySQL SERVER drop table######################## /* Sql_table.cc  delete (drop) tables. */bool mysql_rm_table( )   /*   Execute the drop of a normal or temporary...

   MySQL,DROP TABLE     2012-09-24 11:34:05

  Memory related exception analysis in Java

Java Virtual Machine Specification divides the memory of JVM into several areas : Heap, Stack, The Program Counter register and Method area etc. In HotSpot JVM, heap is composed of Young, Tenured and Perm. There are different OutOfMemory error can happen in different memory area. Next is an overview of some of these OOM errors. StackOverflowError The JVM will allow only a specified number of stacks created nested. An JVM option -Xss can be set to determine the maximum stack size. If the num...

   Java, Memory model, Memory exception, OOM     2015-01-19 06:54:27

  The biggest change ever of iOS--iOS 7

In this year's WWDC, Apple unveils its new iOS--iOS 7. The new iOS has the most significant change since it first came to the public. But many people may be disappointed about this. I am not one of them. In WWDC, Tim Cook said iOS 7 is more flatter than before and it has a completely new user interface design, new slide to unlock feature, official share and weather apps are redesigned. The weather apple now has almost the same feature as the newly updated Yahoo weather application. Ive said the...

   iOS 7,new design,Apple     2013-06-10 22:39:45

  What you may not know about PHP session

When we access one website, the site usually should have a mechanism to keep track of the status of the user on the site. There are a few mechanisms supported by many server side languages to help track user status such as session and cookie. Today we will talk about session, when creating a session, we need to keep track of many data, besides user data, we also need to tell the server what is the timeout of the session so that we can garbage collect the session data which should not be stored a...

   PHP session,session timeout,example     2013-07-06 08:44:18

  When a CA becomes untrustable

Information security has become a vital part of people's life, especially for those people who spend much time online. Tons of data are being transmitted over the internet every second. These data include user ids, passwords, credit card information etc and some of them are sensitive information which needs secure way to transmit. Hence different protocols have been developed including SSL/TLS to encrypt data transmitted over the internet. The core of these security protocols is the certifi...

   APPLE,SECURITY,GOOGLE,MOZILLA,NEWS,WOSIGN     2016-10-01 23:03:44

  Additional steps need to implement to setup shadow-boxV2 OPTEE on Raspberry PI

We followed the Shadow-box v2 project from the https://github.com/kkamagui/shadow-box-for-arm to set up the trustZone on Raspberry PI modeB to protect the Linux Kernel. But got a problem when doing the step: [3.6.5. Activate Shadow-Box for ARM and Start Secure Pi!] to create the hash for the memory area. The result is not shown. If you met the same problem, this is what I did to fix the problem on my PI: 1.1  When we do the step [3.5.1. Copy OP-TEE OS with Shadow-Box for ARM and N...

   HARDWARE,RASPBERRY PI     2019-05-20 08:52:55

  JavaScript cross domain request solution

1. What is cross domain? We may often using AJAX to request data from other domain, now we will have cross domain request issues. It's because JavaScript only allows to request data from the same domain because of security consideration. In short, same domain strategy means a piece of code can read data from the same source, the same source here means the combination of the same domain, protocol and port number. For example: URLDescriptionAllow communication? http://www.a.com/a.js http:/...

   AJAX,cross domain,security     2013-03-13 20:04:52

  10gen provides free training courses for MongoDB

MongoDB is an open source document oriented database, developed with C++, it is to solve some real problems existing among development communities. In October 2007, MongoDB development began at 10gen, in 2009, MongoDB was open sourced as a standalone product. 10gen provides technical support, training and consultancy service. According to 10gen education, 10gen will provide some training courses for MongoDB starting from 22 October, 2012. Now it's available for registration. There are two cours...

   MongoDB,10gen,training,course,free     2012-09-20 22:51:43

  To our youth

Youth is the best period in our life for most of us. We have dreams, passions and energies. We can work day and night for our dreams.We can hang out with friends the whole day. But there will always be a day when we are not young anymore, our youth will pass by. We will not be able to go back to our youth any more. Do you have anything to say about your youth? Recently, a Chinese IT engineer @本座 wrote a short code snippet to describe our youth. Here we share what she writes: public vo...

   Youth,Programming,Rollback     2013-05-02 05:26:56

  Using Fabric to deploy web app

Many people may use FTP and rsync to synchronize codes to server, this way is fine but it may be troublesome when you need to deploy many times a day, actually there is a simple way if you can spend time on finding the fast way. We introduce Fabric today for deploying web app to remote server. Fabric is a deployment tool written with Python, the biggest feature if it is you no need to login to remote server, you can execute remote commands locally. Here is s simple deployment script written with...

   Fabric, Web deployment,SSH,Python     2012-12-08 03:16:00

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