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Product: Book - Paperback
Title: Principles of Two-Dimensional Design
Publisher: Wiley
Authors: Wucius Wong
Rating: 4/5
Customer opinion - 4 stars out of 5
very good little handbook, but really ugly


This book is full of information, and is really well laid out. I use it frequently in the 2D class I teach, along with two other 2D design books. I like the clarity and the examples. However, there's no getting away from the fact that although this book is loaded with great stuff, that it is also as ugly and cheesy looking as a bad Xerox. That might be okay for a math book, but ummmmm, 2D design?



Product: Book - Paperback
Title: Waltzing With Bears: Managing Risk on Software Projects
Publisher: Dorset House Publishing Company, Incorporated
Authors: Tom Demarco, Timothy Lister
Rating: 5/5
Customer opinion - 5 stars out of 5
This is the book!


It is a rare pleasure to find a book that exactly articulates something you have always known but never recognized. This is such a book. It first of all points out that you never will go anywhere without assuming risk. Projects without risk are usually worthless. Given that, you have to then manage risk. Many of us as project leaders would rather simply pretend that risk doesn't exist--and then are upset and annoyed when things go wrong.
Messrs. DeMarko and Lister then proceed to explain exactly how to recognize and deal with risk productively. Their ideas are (and have always been) essential for any project to succeed.



Product: Book - Hardcover
Title: Database Systems: Design, Implementation and Management, Sixth Edition
Publisher: Course Technology
Authors: Peter Rob, Carlos M. Coronel
Rating: 5/5
Customer opinion - 5 stars out of 5
Probably the best book you can buy on databse design


The biggest problem with finding books on designing databases is that there are so few around for a topic that is so important. All the other books I have seen to date have explanations that are either unrealistically convoluted or to simplistic to have any real world use. This book is an exception by presenting data modelling in a practical and logical manner.
The only negative side is that the text in the latest edition is very small but for the only decent book on data modelling that's out there its worth getting out the glasses. I would have given this book 4 stars for its overall value but felt that some of the single stars were unfair.



Product: Book - Paperback
Title: The Data Warehouse Toolkit: Practical Techniques for Building Dimensional Data Warehouses
Publisher: John Wiley & Sons
Authors: Ralph Kimball
Rating: 4/5
Customer opinion - 4 stars out of 5
A very practicle guide


Data warehouse construction is driven by the need to understand customers, products, and key business events. In this way, data warehousing completes the promise of the client-server initiative. The promise is to provide access to data in a timely, flexible, and accurate manner. For those wondering what is a data warehouse, whether they might already be operating one, how to tell if one is needed, and how to build one, Ralph Kimball provides the answers. The fundamental distinction is between operations and decisions. This is the difference between day-to-day operations and management decisions (business strategy and tactics). The processes making up operations include highly granular transactions, stored at the detail level, and on-line transactions processing (OLTP). This is the stuff of classic order entry, inventory control, and general ledger. Decisions require insight and vision about the performance and objectives of the business. Insight and vision require facts about the business delivered "at the speed of business" (fast). Thus, data warehousing consists of modeling the business in terms of basic central facts (units sold or delivered, captured and summarized from operations) in relation to the fundamental dimensions that constitute the business over time. Typically, this results in a multi-dimensional model: a fact structure surrounded by product, customer (market), and time (history). This is the celebrated "star schema" being discussed in the popular trade journals. Kimball claims his work is consistent with the OLAP movement (p. 19) with one difference. His approach is "open," employing de facto industry standard relational technology; whereas OLAP is still proprietary and (more importantly) not robust enough to scale to the enterprise level. This work is remarkably easy to summarize. Chapters Two through Nine take the reader by the hand through a series of progressively more abstract examples of dimensional data modeling in the grocery store, the warehouse, shipments, financial services (banking), subscription services (cable TV), and insurance (casualty). A word of caution, however. If one is interested in insurance, one cannot jump immediately to that chapter. It builds on groundwork laid in preceding chapters. So, for example, to understand why products in insurance and banking are so diverse they do not belong in the same relational table, it is useful to appreciate the homogeneity and comparability of canned products on a grocery store shelf. For computing professionals, the wealth of functional business distinctions, especially in connection with the relational database model, is instructive. This results in useful suggestions on how the relational model can be extended as well as measures needed in application code until such extensions occur. For example, measures that record a static level (inventory, financial account balances) are not additive across time. Balances cannot simply be added, but must be averaged by time period. Since the SQL AVG function considers rows returned, not time periods relevant (PERIODAVG), average period sum must be calculated in an application or proprietary SQL extension. The performance challenge of data warehousing is large. This can be appreciated by considering product, customer, and time dimensions of an average of 10,000 distinctions each. Without sparcity (not all combinations occur), the result is a combination on the order of 100 billion rows. Naturally, the problem is made worse for phone companies and banks which have millions of customers (see Chapter 6: "The Big Dimensions"). Kimball claims that the limits of current relational technology (circa 1995) are reached at about 1 billion rows or about 100 gigabytes. The answer is considered in Chapter 13 on Aggregation. Since an endless horizon of business days tends to cause combinatorial explosion of the facts at an elementary level, it is useful to define aggregations (summations) which group twenty or more facts together. Combine and store the data on a weekly or monthly basis rather than daily. The trade-off is between more work transforming data in long-running batch process prior to loading and quicker on-line response time to queries submitted interactively. The work contains a wealth of practical advice for the information technology practitioners. For example, when the relative size of the central fact table is compared to that of the surrounding dimension structures (differences of orders of magnitude are common), it is clear that little disk space can be saved in normalizing the latter. As a text, the book is superbly prepared. It comes with a CD-ROM containing an ACCESS version of the databases described in the book and sample queries against the databases. The reader is provided with a complete glossary of terms, appendixes, index (no bibliography) and a useful summary of design principles of a dimensional data warehouse. For this reviewer, the continuity with the discipline of data modeling, data administration, and data mining (customarily called "logic"), is useful and productive. Much of what occurs in decomposing data into relational structure by means of the process of applying Codd's "normal forms" is relevant here. But with a new "spin". The structure of the data gives us insight into the kinds of questions might be asked. Thus, the prospect of packaging a large, but finite, set of SQL queries can be envisioned. Kimball is to be congratulated on taking the "hype" out of data warehousing and showing its importance as an application of relational technology to business practices. -- excerpt from my review originally published in Computing Reviews, November 1996