perpetual
发表于 2025-3-25 04:26:38
How Skewness Can Make Your Execution Times Variable,ased 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.
顽固
发表于 2025-3-25 07:54:47
Troubleshooting Query Transformations,ate execution plans that are both easy to generate and that run fast. The optimizer uses a number of “tricks” along the way to improve the speed of execution and implements the execution plan in a way that gives the same results as your unmodified SQL. These “tricks” (or heuristics) sometimes includ
附录
发表于 2025-3-25 13:43:33
Forcing Execution Plans Through Profiles,ion time pressures to get something done, any way that works is good enough. The idea is to get the business back up and running, then sit at your leisure and work out what went wrong, figure out how to stop it from happening again, and develop a plan to implement the permanent fix in a controlled m
软弱
发表于 2025-3-25 18:21:33
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勤劳
发表于 2025-3-25 22:10:28
Dynamic Sampling and Cardinality Feedback,been told there are 2 or 3 books in the study, and that there is an index in the desk if you need it. Naturally with 2 or 3 books or even a dozen books, there’s no point in using the index in the desk, you’ll just look at the book titles one by one and quickly find all of the books with “Vienna” in
antiandrogen
发表于 2025-3-26 03:10:23
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conduct
发表于 2025-3-26 07:39:55
Comparing Execution Plans,t plan as a guide to bring the bad execution plan into compliance. In Chapter 6 we talked about using SQL Profiles to apply a plan onto another database’s SQL, in order to have an emergency option. Suppose, however, you have more time to consider the difference and try to fix it properly, rather tha
放纵
发表于 2025-3-26 11:08:56
Building Good Test Cases,spects have been eliminated and a more thorough investigation may be required. In cases like these it is useful to build a test case to allow experimentation away from the main environment. If you are investigating a problematic SQL in a test environment, normally you would try and make the environm
impale
发表于 2025-3-26 13:37:50
Using XPLORE to Investigate Unexpected Plan Changes,the test case utility and how that could build an entire environment for testing SQL, system parameter, optimizer settings, objects statistics, enough of the settings in fact to make the optimizer behave as if it was on the source system. Once you achieve that state you have a superb environment to
破裂
发表于 2025-3-26 20:10:34
Trace Files, TRCANLZR and Modifying SQLT behavior,ret 10046 files is outside the scope of this book. The standard guide for this is Cary Millsap’s book . (O’Reilly 2003). (This book is a little dated now, but still contains useful information on 10046 trace files.) How to more easily collect these trace files, however, and format them so they are e