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  Why are column oriented databases so much faster than row oriented databases?

I have been playing around with Hybrid Word Aligned Bitmaps for a few weeks now, and they turn out to be a rather remarkable data structure.  I believe that they are utilized extensively in modern column oriented databases such as Vertica and MonetDB. Essentially HWABs are a data structure that allows you to represent a sparse bitmap (series of 0's and 1's) really efficiently in memory.  The key trick here is the use of run length encoding to compress the bitmap into fe...

   Database,Column oriented,Speed analysis,Vertica     2012-01-29 04:27:05

  The price of information

SOMETIMES it takes but a single pebble to start an avalanche. On January 21st Timothy Gowers, a mathematician at Cambridge University, wrote a blog post outlining the reasons for his longstanding boycott of research journals published by Elsevier. This firm, which is based in the Netherlands, owns more than 2,000 journals, including such top-ranking titles as Cell and the Lancet. However Dr Gowers, who won the Fields medal, mathematics’s equivalent of a Nobel prize, in 1998,...

   Information,Price,Value,Facebook,Social network     2012-02-07 06:24:53

  Google will close shopping search service in China

Google vice president of products Sameer Samat posted a news on Google Blackboard, since the service failed to meet the expectations, in order to better optimize resources, Google decided to close the shopping search service in China.In order to better optimize resources, we have decided to close the shopping search service in China. The original intention of the development of this product is to set up a bridge between consumers and retailers and traders. However it did not meet our expectatio...

   Shopping search service, Google China     2012-12-12 14:30:44

  HTTP Streaming and Internet Explorer

In early 2006, Alex Russell posted about a neat hack that the Google Talk team in Gmail use to support Comet in Internet Explorer, a trick which works as far back as IE 5.01. What great news! A reliable way to stream Comet messages to Microsoft’s browsers. If only it were that easy. I have not been alone in the following findings: after connecting the htmlfile ActiveX object as a streaming Comet transport to my Comet server, everything works perfectly for a few messages, but then abruptly...

   IE,Streaming,JavaScript,htmlfile,ActiveX     2011-09-05 04:05:23

  Tips of Drafting an R Markdown Document

When presenting the data summary and exploratory analysis, we used to copy a lot of tables, charts from Rstudio to PowerPoint, which makes the presentation preparation painful. It becomes essential for data scientists to make use of better reporting tools, such as R markdown, Jupyter notebook to prepare the analysis presentation in a more efficient and organized way. Of course, we want this to be reproducible! In this post, I would like to share some tips of using the right tools to draw tables,...

   R PROGRAMMING     2020-11-01 23:09:45

  Add Sublime Text to your context menu on right click

When opening a text file, you may be used to right click on the file to be opened and then choose the application which can open the file from the context menu. On the context menu, you may see a menu item like "Edit with Notepad++". Nowadays many people especially programmers like to use Sublime Text, but by default this application will not show on the context menu when you right click on a file. There is now frequent request to add this application to the context menu. Here we show a simple b...

   SUBLIME TEXT,CONTEXT MENU,WINDOWS     2015-10-19 08:51:25

  Understanding database, instance and schema in Oracle database

Oracle database is the most popular database system among enterprises. To start working on Oracle database, some concepts must be understood first. They include database, instance, schema and user etc. And among these concepts, some have different meanings from those in other database systems such as MS SQL, MySQL, DB2. On the web, there are already some good posts which explain different concepts such as Ask Tom's database vs instances, Difference between database vs user vs schema. In this pos...

   DIFFERENCE,DATABASE,ORACLE DATABASE,INSTANCE,SCHEMA,USER     2016-12-14 23:30:56

  I’m too lazy to be a HTML developer

There’s no denying it. I’m just to damn lazy to be an HTML developer. This really sunk in when I looked at a tutorial for doing a jQuery Lightbox – for a client project. The tutorial was titled “Super Simple Lightbox with CSS and jQuery” but after reading it over I thought a better title would be “A really freaking hard tutorial on the inane intricacies of doing something that looks simple but in reality is a skein of HTML, Javascript and CSS that no...

   Web design,HTML,JavaScript,Complexity,Messy     2011-12-18 10:42:45

  Three Simple Ways to Improve the Security of Your Web App

It seems like web app security has entered the public conscious recently, probably as a result of the press covering the activities of groups like Anonymous and incidents like security breaches at several CAs. Here are a couple of quick security tips to improve the security of your web apps. Think of these as low-hanging fruit, not as a substitute for thorough analysis of your app’s security. If there’s interest in this topic we can do more posts, too - let us know in the com...

   Web app,Security,X-FRAME-OPTIONS,SSL     2011-12-08 10:10:20

  SSH Security and You - /bin/false is *not* security

Backstory While at RIT around 2004 or 2005, I discovered that a few important machines at the datacenter allowed all students, faculty, and staff to authenticate against them via ssh. Everyone's shells appear to be set to /bin/false (or some derivative) on said machines, so the only thing you'll see after you authenticate is the login banner and your connection will close. I thought to myself, "Fine, no shell for me. I wonder if port forwarding works?" ...

   Linux,Security,/bin/false,SSH     2012-02-06 07:46:29

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