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Performance Tuning – The wrong way

02 September,2015 by Tom Collins

Example 1: There are no performance requirements. No one has set any expectations. Job Done! It is very common for performance requirements to be an afterthought.

Setting some performance criteria as part of the planning phase , will help DBAs focus on server architecture and implementation.

Example 2: Tuning with the power of mysticism or relying on religion . Performance Tuning is all about understanding the applications and setting  performance expectations . This requires measuring .  You can read all the  performance manuals  – they won’t give you the power of context. To paraphrase Malcolm Gladwell “SQL Servers  are sensitive to the conditions and circumstances of the times and places in which they occur".

Every decision should be made with measurements. Avoid guesswork and learn to rely on measurable improvements

Example 3 :Google is my best friend. Applying random code from Google, without any testing.


Example 4 : “But my system works this way”

Often in this situation a quick diagnosis will reveal the root cause . It’s more difficult to  convince the application owner or developer that implementation is the root of the problem

Example 5: Not listening to the system. The signals are coming from SQL Server – you just need how to read and interpret the signals

Example 6: Not profiling in Production system . Profiling – is a statistical sampling technique. Lots of tools hide the real detail with lots of useless data. Useless data can lead you to false assumptions or creating new problems

Also it is expensive to capture the data

SQL Performance tuning - Drilling into the problem - SQL Server DBA

Example 7: Going straight into the code. As a Production DBA it’s often easier to assume the local knowledge is the correct interpretation.Developers have a different mindset .  Sometimes you can tell developers what to avoid – but they can’t help themselves. The keep repeating the same mistakes

5 things SQL Server developers should know about SQL Server

Example8: Poor system visibility . What does monitoring give you? Yes , loads of data but does it offer clarity. Most application logs are focused on delivering useful information for developers and the development process.  

Reason 9:Kill it with iron. Find first understand the bottleneck. Leave the hardware solution as last resort

The future of the SQL Server Performance Tuning Expert - SQL ...

Readon 10: Performance Tuning by committee. Usually means technology used is not understood by anyone. Tribal behaviour can lead to deep misunderstandings and to a solution not fit for purpose.



Read More on effective DBA practises and common DBA mistakes

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Author: Tom Collins (


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