- Taschenbuch: 536 Seiten
- Verlag: Apress; Auflage: 1st ed., Corr. 3rd printing (24. Januar 2007)
- Sprache: Englisch
- ISBN-10: 1590596366
- ISBN-13: 978-1590596364
- Größe und/oder Gewicht: 19 x 3,1 x 23,5 cm
- Durchschnittliche Kundenbewertung: 2 Kundenrezensionen
- Amazon Bestseller-Rang: Nr. 289.504 in Fremdsprachige Bücher (Siehe Top 100 in Fremdsprachige Bücher)
- Komplettes Inhaltsverzeichnis ansehen
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Cost-Based Oracle Fundamentals (Expert's Voice in Oracle) (Englisch) Taschenbuch – 24. Januar 2007
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The question, "Why isn't Oracle using my index?" must be one of the most popular (or perhaps unpopular) questions ever asked on the Oracle help forums. You've picked exactly the right columns, you've got them in the ideal order, you've computed statistics, you've checked for null columns--and the optimizer flatly refuses to use your index unless you hint it. What could possibly be going wrong? If you've suffered the frustration of watching the optimizer do something completely bizarre when the best execution plan is totally obvious, or spent hours or days trying to make the optimizer do what you want it to do, then this is the book you need. You'll come to know how the optimizer "thinks," understand why it makes mistakes, and recognize the data patterns that make it go awry. With this information at your fingertips, you will save an enormous amount of time on designing and trouble-shooting your SQL. The cost-based optimizer is simply a piece of code that contains a model of how Oracle databases work. By applying this model to the statistics about your data, the optimizer tries to efficiently convert your query into an executable plan.Unfortunately, the model can't be perfect, your statistics can't be perfect, and the resulting execution plan may be far from perfect.In Cost-Based Oracle Fundamentals, the first book in a series of three, Jonathan Lewis--one of the foremost authorities in this field--describes the most commonly used parts of the model, what the optimizer does with your statistics, and why things go wrong. With this information, you'll be in a position to fix entire problem areas, not just single SQL statements, by adjusting the model or creating more truthful statistics.
Über den Autor und weitere Mitwirkende
Jonathan Lewis has been working in the information technology industry for nearly 25 years, and has been using the Oracle relational database management system for more than 20. For the past 16 years, he has worked as a freelance consultant, often spending only one or two days at a time with any client to address critical performance problems. He also advises on design and implementation problems, and on how to make best use of the most appropriate Oracle features for a given project. Jonathan is also renowned throughout the world for his tutorials and seminars about the Oracle database engine and how to make best use of it. Having visited 42 countries at last count, his exceptional ability has earned him an O1 visa from the United States, allowing him to do consultancy and lecture work there. Jonathan has written two books about Oracle (Practical Oracle8i, Addison-Wesley, 2000; Cost-Based Oracle Fundamentals, Apress, 2005), and has contributed to two others (Oracle Insights, Apress, 2004; Oracle Database 10g New Features, Oracle Press, 2004). He also writes regularly for the UKOUG magazine, and occasionally for other publications around the world. In the limited amount of time he has leftover, Jonathan also publishes high-tech Oracle articles on his blog at jonathanlewis.wordpress.com.
Derzeit tritt ein Problem beim Filtern der Rezensionen auf. Bitte versuchen Sie es später noch einmal.
Why only 4 stars? At times this book focuses too much on detail - especially in the style of writing. It is sometimes hard to get to the concepts from this detailed point of view. Of course the author provides summaries per chapter. However many of the chapters start with some script and the resulting details of this script. The concept this leads to is then mentioned later on in the chapter - it's mostly a question of personal taste. Personally I prefer the style of writing in Guy Harrisons book on the same topic, however Harrison is not as detailed and the Harrison Book only covers Oracle 8, while this one has information up to Oracle 10 Release 2.
So to sum this up: Recommended for anyone interested in the real details of performance tuning and how the optimiser works / where the pitfals are. Only negative is my personal (dis)taste for the style of writing.
Mein bestes Erlebnis: Statt unsere Terabyteproduktiv DB komplett in die Testdatenbank zu laden umd unsere Entwickler mit relevanten Ausführungsplänen zu versorgen, wurde einfach das "Statistik hacken" - was ja kein richtiges hacken ist - des Buches angewandt. Mit den angegebenen Formeln usw. konnte auch dargelegt werden das z.b. befremdliche Defaultwerte (9999 für Jahr oder der ewige Dauerbrenner für Datumswerte Zeichenfolgen statt Datums Feldtypen zu verwenden) nicht das gelbe vom Ei sind. Zwar nur 2 Problemdarstellungen aus dem Buch aber die konnten effektiv auf unser Datenmodell angewandt werden.
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Even after working with CBO trace so long, I am still learning a lot from this master. Mr. Lewis combats each component of CBO separately in a chapter format and provides examples & test cases for each of his observation and working principles. He anlyzes the results logically providing valuable insights. Every statement he makes is verifiable using the test case he provides or metalink note is referenced and no myth producing elements in his statements.
Resolving the root cause solves the problem once for all. Understanding the optimizer internals is very important to resolve the root cause of a SQL performance problem. [You can add a hint and resolve the problem, but that is usually a band-aid, not a solution to the problem]. There is no other book that deals with the root cause analysis of CBO comparable to this book.
He goes further explaining the reasoning behind the optimizer decisions. While reading the book, I had a few flashbacks such as ' Aha, that's why that query didn't work before rewriting it! I wish I read this book earlier and could have solved without a time-consuming rewrite'.
Every DBAs / performance tuners should read this book and hold on to it.
Kudos to Mr. Lewis! Looking forward for more books!!
Within the book, Jonathan provides insights into how the CBO *should* work. He follows up often by demonstrating the maturing (or devolving as the case may be) of the CBO from version to version. Beyond his own experimentation and results, he leads the reader into the process that he has followed to come to understand the internals of the CBO, providing a road map allowing the reader to continue to explore the optimizer in future releases.
However, I must take Jonathan to task, for he is a nasty tease. This book was released about two years ago. In it, he leads us on with promises of forthcoming volumes 2 and 3, dangling the carrot out there for us to follow. Sadly, these volumes are yet to be seen. Jonathan! Quit running to and fro filling our heads with knowledge at various conferences and write those books man!
A caution for the new DBA or the cursory SQL developer, you may find this book overwhelming at first glance. For the new or even intermediate DBA, it might be hard to derive practical application of what Jonathan is teaching at first glance. Take your time with the material and the insight that you will gain will be invaluable.
Overall, if you want a book with meat, then this is the book for you. It will expand your mind and the way you look at the Oracle CBO.