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Showing posts from April, 2012

What is the Difference Between Web Design and Graphic Design?

Although web design and graphic design both use images, text, and typeface to create a desired method of communicating ideas, designing for web and print are two different practices. Graphic designers have been around since print media was created, while web design came into being when the Internet was developed. Before choosing a print designer or web designer, it is important to understand the differences between web design and graphic design. Graphic Design Graphic Design includes any type of design that has been created and printed. Graphic design uses the blending of technology and art to communicate messages and ideas. The graphic designer utilizes a number of communication tools to deliver a message from a client/company to a specific audience. Graphic design illustrations can be found in magazines, newspaper arrangements, newspaper ads, billboards, logos, brochures, books, labels on a variety of product packages, and much more. Graphic designers create the layout design for a v

Take screenshot with ImageMagick (CLI)

Take full screen screenshot with 3 seconds delay # import -pause 3 -window root screenshot.jpg Take selected area screenshot # import screenshot.jpg

Understanding the database query optimization

Query optimization is the process of extracting most efficient query from a complex query.  To extract efficient query, query optimizer maintains some strategy or rules. Think that we work on huge data and it takes long time  to run a simple query. And also think when we run a complex query what will occur? To solve this problem query optimizer finds solution by following some rules. To find the least costly query evaluation plan the optimizer needs to generate alternative plans that produce the same result as the given expression and to choose the least costly one. Generation of query evaluation plans involves two steps: 1. Generating expressions that are logically equivalent to the given expression. 2. Annotating the resultant expressions in alternative ways to generate an alternative query evaluation plan. The optimize query must be same as the original query. Now consider the relational algebra expression for the query "Find the names of all customers who have an account at

Thomas' Write Rule Correctness of Timestamp Protocol

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We know timestamp based schedules are not recoverable and also there is a possibility of starvation. If this problem is recoverable by maintaining some rules but Thomas' Write Rule is the best solution for Timestamp based protocol. This part of the tutorial I described Thomas' Write Rule. In this rule read operation remain unchanged but write operations are different from the timestamp-ordering protocol.  Suppose that transaction Ti issues write ( Q) and the Thomas' rule is: A. If TS ( Ti) < R - timestamp ( Q) then the system reject the write operation and Ti is rolled back. Because at any transaction the first operation must be read operation. B. If TS ( Ti) < W- timestamp ( Q) then the operation rejected and Ti is rolled back. Because this write operation attempting to produce obsolete value. C. Otherwise the system executes the write operation. Now consider the following schedule. In this schedule T1  starts before T2 and we assume that TS ( Ti)<TS ( T2). The

Timestamp-Based Protocols in Database

In general timestamp means a sequence of characters. In database to maintain serializability the transaction maintains ordering that is called timestamp ordering scheme. Let a unique timestamp is denoted by TS ( Ti) where Ti is the transaction number. This timestamp TS ( Ti) is assigned by the database system before new transaction Tj enters the database system. In timestamp protocol transaction maintain serial order. Let Q is the data item. So we denote two kind of timestamp such as  W- timestamp ( Q) that executed write ( Q) successfully. R- timestamp ( Q) that executed read ( Q) successfully. The timestamp based protocol ensures read and write operations are executed in timestamp order. Timestamp protocol must maintain this following condition.  Condition 1: Transaction Ti issues read ( Q) A. If TS ( Ti)<W- timestamp ( Q) then read operation is rejected and Ti is rolled back because Ti wants to write but it was already written. B. If TS ( Ti ) =>W-timestamp then read

Dragon Age 2 - Loading Screen [Solved]

Why my Dragon Age 2 hangs at the loading screen? How to make my game work? The answer is simple. Lets blame it on Microsoft rather than Bio Ware. Because, the game get stuck due to the Direct X 11. Solution  : When you open the game launcher, click the Configure button to open a Configuration Utility . In that dialog choose the Video option from the left panel. Under the  Rendering option  choose Direct X 9 than 11 . Blame : As I told you blame Microsoft for not improvising Direct3D to be compatible for its-older-version-dependent games. Almost any EA Games run in Direct X 9.0[x] (x = usually 'c' i.e. 9.0c) than the other versions. Like it? Recommend to other players . . . Have a Dragon Day :)

Graph-based protocol in database

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In two phase protocol there are many problems. This protocol cannot able to handle deadlocks. To solve this problem we use Graph-Based Protocol. This protocol maintains partial ordering of data items. Think that the data item D1, D2.................  Dn .  In any transaction at first it accesses D1 before accessing D2 and so on. In this purpose we can say that Graph based protocol consider prior knowledge to lock or unlock data item. There are many Graph based protocol exists but for simplicity I just describe tree protocol. Tree protocol is allowed only exclusive locks. The tree protocol must  maintain the following rules: 1. The first lock may be any data item. Subsequently, a data item Q can be locked by Ti only if the parent of Q is currently locked by Ti. 2. Data item may be unlocked at any time. 3. A data item that has been locked and unlocked by Ti cannot subsequently be relocked  by Ti . To describe this protocol, consider the picture bellow. And also consider this four transac