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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

  CASSANDRA data model

Cassandra is an open source distributed database, it combines dynamic key/value and column oriented feature of Bigtable. Features of Cassandra are: Flexible schema, no need to design schema first, it's very convenient to add or delete strings Support range search on keys High usability, extensible. The single node error will not affect the cluster. We can think Cassandra's data model as a 4 or 5 dimensional Hash. COLUMN Columns is the smallest data unit in Cassandra, it is a 3 dimensional data...

   Cassandra,database,sort     2013-06-08 22:07:40

  XMLHttpRequest Level 2 user guide

XMLHttpRequest is a web browser interface, it makes it possible for JavaScript doing HTTP(s) communication. Microsoft's IE5 first introduced XMLHttpRequest, because it's so useful that many other browsers also adopted this. AJAX came to the front since. However, this interface is not standardized, implementation among different browsers is different, with the emerging of HTML5, W3C is considering to standardize this interface. In February 2008, they proposed a XMLHttpRequest Level 2 draft. This ...

   XMLHttpRequest, progress, upload, binary data     2012-09-19 11:51:50

  9 useful jQuery code snippets

jQuery is one of the most popular JS library among front end developers because of its functionality and usability. Here we share with you some useful jQuery code snippets which can be used in our daily front end development. 1. Smoothly return to page top $(document).ready(function() { $("a.topLink").click(function() { $("html, body").animate({ scrollTop: $($(this).attr("href")).offset().top + "px" }, { duration: 500, easing: "swing" ...

   jQuery,Code snippet     2013-07-13 00:11:10

  Difference between keystore and truststore

Security has become a vital concern in most of the online transactions nowadays. Lots of the world's most popular websites have adopted security protocols to transfer data, especially sensitive data. These security protocols including SSL/TLS which are using the private/public key exchange mechanism to establish secure connections.  The private/public key cryptography is a really important invention and it allows data to be transferred securely and solves the big problem of transferrin...

   KEYSTORE,TRUSTSTORE,SECURITY,SSL     2017-03-04 07:52:47

  Mastering Async/Await in JavaScript: A Comprehensive Guide with Examples

As a veteran JavaScript developer, I have seen the evolution of JavaScript's asynchronous programming landscape. From callbacks to promises and now async/await, JavaScript has come a long way in making it easier to handle asynchronous operations in a clean and readable manner. In this article, we will delve into the world of async/await and explore why it has become a popular choice for handling asynchronous operations in JavaScript. We will cover the basics of async/await, its syntax, and how i...

   JAVASCRIPT,COMPARISON,PROMISE,ASYNC AWAIT     2023-02-12 07:26:15

  CSS Selector for Web Scraping

Creating a web scraper is no easy task. This is because it requires precision to identify the specific data points that we intend to collect for the end goal we are working towards.  Whether we are looking to create a marketing content database or analyze market trends, the last thing we need from our scraper is for it to return a lot of unnecessary data that will not help our cause. To avoid the inconvenience of going through huge amounts of data to get what we requested, it is crucial to ...

   CSS,WEB DESIGN,SELECTOR     2023-02-20 07:32:53

  Using JavaScript to operate clipboard

Browsers allow JavaScript to read and write data on clipboard. Generally script should not modify user's clipboard to avoid impacting user expectation, but there are cases where this can indeed bring convenience to users. For example, for some code snippet, user can copy it to clipboard with one click instead of select and copy manually. There are three options for clipboard operation provided in JavaScript/browser: document.execCommand() Asynchronous Clipboard API copy and paste events This p...

   JAVASCRIPT,CLIPBOARD,NAVIGATOR.CLIPBOARD     2021-01-23 23:23:34

  The war with spam comment

Spam comments are annoying and notorious. They are either malicious data from hackers to exploit the loopholes of the site or advertisements posted by robots. These kinds of comments have their own features and patterns, if we are careful enough, we can find ways to block most of them although it's not so easy. To block the comment with malicious executable codes such as JavaScript, we should remember one rule : never trust user input. So wherever there are user inputs, we need to check the vali...

   Spam comment,Block,Filter     2013-11-29 20:29:43

  Generate certificate from cert file in Java

A certificate is often used to prove the identity of a server. The certificate will contain information such as the subject and issuer of the certificate. It will also contain the validation date of the certificate. A certificate is often exported to an external cert file which is transferred over the internet. We will often see its use in SSL communication which provides secure communication between two entities. In this post, we will show how to read the data from an external certificate file ...

   PKCS12,CertificateFactory,Example,Java,X509     2015-06-08 06:47:05

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