Simulation and performance analysis of distributed Internet systems using TCPNs.(timed coloured cetri net)(Report)

This paper presents a Timed Coloured Petri Nets based programming tool that supports modeling and performance analysis of distributed World Wide Web environments. A distributed Internet system model, initially described in compliance with Queueing Theory (QT) rules, is mapped onto the Timed Coloured Petri Net (TCPN) structure by means of queueing system templates. Then, it is executed and analyzed. The proposed distributed Internet systems modeling and design methodology has been applied for evaluation of several system architectures under different external loads. Keywords: distributed systems modeling, performance analysis,...

Similarity measures for relational databases

The relational algebra (4; 15), a relational data model with five basic operations on relations, i.e., Cartesian product x, projection [pi], selection [sigma], union [union], and set difference --, and several additional operations such as [theta]-join or intersection, has three main advantages over non-relational data models (13): --From the point of view of usability, the model has a simple interpretation in terms of real-world concepts, i.e., the essential data structure of the model is a relation, which can be visualized in a tabular format. --From the point of view of applicability, the model is flexible and general,...

Applying SD-tree for object-oriented query processing.(signature declustering)(Report)

The advent of internet has made the volume of data going high everyday in all computer-based applications. This has entrusted researchers to design more powerful techniques to generate and manipulate large amounts of data to derive useful information. Indexing plays a vital role in the fast recovery of required data from large databases. Among the many indexing techniques reported the signature file approach is preferred for its efficient evaluation of set-oriented queries and easy handling of insert and update operations. Initially applied on text data [2, 3, 12, 17, 21] it has now been used in other applications like office...

Multiple executions ETL process against same set of data.

Every ETL designer, developer & tester should always ask this question…”What will happen, if I run the ETL process multiple times, against the same data set?” Answer: 1. I get the same result set. Answer: 2. I get multiple result set. If you go back to the original article on What is ETL & What ETL is not! You will immediately come to the conclusion that Answer 2 is incorrect, as ETL is not allowed to create data. Why will the process run more than once against the same set of data? Many reasons, example most common being operators mistake, accidental kickoff, old set of data file remaining in the directory, staging...

The Problem with Dimensional Modeling

The problem with dimensional modeling is... well there really isn't a problem with dimensional modeling. In terms of capturing requirements for DSS analysis, dimensional modeling is undoubtedly the best technique for design that there is. Hundreds of organizations have used dimensional modeling successfully and are quite satisfied with the results. There are classes and conferences where dimensional modeling is the focus and the attendees walk away with a happy smile on their face. So whatever could be the problem with dimensional modeling? In fact, is there really a problem here? In order to understand what the issues are,...

Data Mining: An Introduction

By this point in time, you've probably heard a good deal about data mining -- the database industry's latest buzzword. What's this trend all about? To use a simple analogy, it's finding the proverbial needle in the haystack. In this case, the needle is that single piece of intelligence your business needs and the haystack is the large data warehouse you've built up over a long period of time. Data Mining in Business Through the use of automated statistical analysis (or "data mining") techniques, businesses are discovering new trends and patterns of behavior that previously went unnoticed. Once they've uncovered this vital...

How important is Extract, Transform, Load (ETL) to data Warehousing?

Politicians raising money can be used as an analogy to compare data cleansing to data warehousing. There is almost no likelihood of one existing without the other. Data cleansing is often the most time intensive, and contentious, process for data warehousing projects. What is Data Cleansing? The elevator pitch: "Data cleansing ensures that undecipherable data does not enter the data warehouse. Undecipherable data will affect reports generated from the data warehouse via OLAP, Data Mining and KPI's." A very simple example of where data...

Informatica Repository Manager

Q. What type of repositories can be created using Informatica Repository Manager? A. Informatica PowerCenter includeds following type of repositories :     Standalone Repository : A repository that functions individually and this is unrelated to any other repositories.     Global Repository : This is a centralized repository in a domain. This repository can contain shared objects across the repositories in a domain. The objects are shared through global shortcuts.     Local Repository : Local repository is within a domain and it’s not a global repository. Local repository can...

What is lookup transformation in informatica?

Lookup is a transformation to look up the values from a relational table/view or a flat file. The developer defines the lookup match criteria. There are two types of Lookups in Powercenter-Designer, namely; 1) Connected Lookup 2) Unconnected Lookup . Different caches can also be used with lookup like static, dynamic, persistent, and shared(The dynamic cache cannot be used while creating an un-connected lookup). Each of these has its own identification. For more details, the book "Informatica Help" can be useful. Hope you are aware with the basics of Informatica. Now proceeding through lookup transformation. Lookup transformation...