Cost-Based Oracle Fundamentals / Edition 1

Cost-Based Oracle Fundamentals / Edition 1

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by Jonathan Lewis
     
 

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

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Overview

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.

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Product Details

ISBN-13:
9781590596364
Publisher:
Apress
Publication date:
11/02/2005
Series:
The Expert's Voice in Oracle Series
Edition description:
1st ed. 2005. 2nd printing 2007
Pages:
536
Sales rank:
1,323,267
Product dimensions:
7.00(w) x 9.25(h) x 1.08(d)

Table of Contents

Ch. 1What do you mean by cost?1
Ch. 2Tablescans9
Ch. 3Single table selectivity41
Ch. 4Simple B-tree access61
Ch. 5The clustering factor87
Ch. 6Selectivity issues115
Ch. 7Histograms151
Ch. 8Bitmap indexes181
Ch. 9Query transformation207
Ch. 10Join cardinality265
Ch. 11Nested loops307
Ch. 12Hash joins319
Ch. 13Sorting and merge joins353
Ch. 14The 10053 trace file403
App. AUpgrade headaches453
App. BOptimizer parameters465

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