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Author: |
RichardTo |
Created: |
Monday, October 30, 2006 2:28 PM |
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Solving problems in your SQL code, tune queries, and share new tips, tricks, and techniques |
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A New Intelligent Test Run Function is under Research |
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RichardTo
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Friday, June 13, 2008 3:20 AM
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A problem in the area of SQL optimization that has been around for a long time is the inaccuracy of the cost estimation of a SQL statement. A lot of people have the wrong conception that inaccurate cost estimations generated for a SQL statement by the database optimizer are caused by outdated statistics; whereas in fact, outdated or incorrect statistics is only one o ...
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Batch Optimizer Part 4 – Options Settings for the Batch Optimizer |
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RichardTo
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Friday, May 09, 2008 5:53 AM
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Written by Rene Woody
This blog is a continuation of a series about the Batch Optimizer in Quest SQL Optimizer for Oracle. It covers the execution options settings for determining the criteria for selecting the best alternative, for terminating longer running SQL, and eliminating the effect of caching on the comparison ru ...
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Batch Optimizer Part 1 – How the Batch Optimizer Works |
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RichardTo
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Friday, March 28, 2008 4:01 AM
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Written by Rene Woody
We all know that it is important to create SQL statements that perform well in our database environment, but all too often, after creating a SQL statement that retrieves the correct results, the optimizing of the SQL statement is left for another time. Frequently, that time never arrives. Quest SQL ...
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How to use the Quest SQL Optimizer |
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RichardTo
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Tuesday, March 18, 2008 5:31 AM
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Written by Rene Woody
Quest SQL Optimizer can do an extensive transformation of the syntax of a SQL statement while still maintaining the exact same result set. This exhaustive transformation can produce hundreds of SQL alternatives. So it is necessary to have some insight as how to find a SQL alternative that is better than your ...
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What about a Self-learning SQL Optimizer? |
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RichardTo
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Tuesday, October 09, 2007 4:45 AM
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There are at least two database vendors are trying to build self-learning SQL optimizers. The idea is to use actual statistics from executed SQL statements to rectify the future cost estimation of the same or similar SQL statements. It seems like a good idea, but, you will find that their existing self-learning ...
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A SQL Performance History from AWR |
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RichardTo
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Thursday, September 13, 2007 2:51 PM
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I have been working on SQL Tuning research for more than 10 years, but my focus has changed to time-series forecast technology in the last two years. Recently, Oracle’s AWR and other database vendor’s statistics/metrics repository have drawn my attention. The relatively low cost of keeping performance statistics in databases, combined wi ...
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How Quest SQL Optimizer works with Hints |
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RichardTo
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Tuesday, August 14, 2007 10:28 AM
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Today database vendors are more willing to provide a means for the end user to influence the decision of which execution plan to use for a SQL statement. They provide this because database optimizers cannot guarantee that they the will generate the best execution plan for a given SQL statement. However, when you do apply Optimization Hints you ...
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