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Oracle SQL Tuning with Oracle SQLTXPLAIN: Oracle Database 12c Edition, Second Edition
book

Oracle SQL Tuning with Oracle SQLTXPLAIN: Oracle Database 12c Edition, Second Edition

by Stelios Charalambides
April 2017
Intermediate to advanced
436 pages
12h 7m
English
Apress
Content preview from Oracle SQL Tuning with Oracle SQLTXPLAIN: Oracle Database 12c Edition, Second Edition

© Stelios Charalambides  2017

Stelios Charalambides, Oracle SQL Tuning with Oracle SQLTXPLAIN, 10.1007/978-1-4842-2436-6_5

5. How Skewness Can Make Your Execution Times Variable

Stelios Charalambides1 

(1)New Hampton, New Hampshire, USA

Skewness is one of those topics that for some reason is often ignored, or misunderstood. Skewness is an important part of data handling for the cost-based optimizer. It makes a difference as to what the optimizer decides to do. It is so important that Oracle created new features such as Adaptive Cursor Sharing just to handle the consequences of skewness. Skewness and the types of skewness are so important that in 12c there are more types of histograms to take account of the different ways in which data can be skewed. ...

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Publisher Resources

ISBN: 9781484224359Purchase book