Performance tuning your SQL Server applications shouldn’t be delegated to the end of your development process. In order for your SQL Server-based applications to run and scale at their full potential, you should consider performance and scalability during the early stages of the development.
You have probably run across some slow running applications that were SQL server based if you have been an SQL developer or a DBA. Often, when SQL performance problems arise, people point to different causes. For example, you may get one engineer arguing that the problem is with hardware while someone else may say that it’s related to new code. This approach is rarely helpful.
In an ideal scenario, proper architecture design is the best way to ensure that SQL server application performs optimally. This includes careful up front analysis of the functional requirements for database application, design that is highly scalable and following best coding practices.
Performance and scalability need to be built into any SQL Server database application whether it’s small or large. After the application is deployed, it can be very expensive and difficult to resolve performance and scalability issue.
The team responsible for SQL Development needs to have a strong background in design and implementation scalable applications that are optimized from the start.
In addition, performance and scalability testing should be scheduled throughout the software development cycle, long before the application is ready for production. Performance testing needs to be an integral part of the development process, starting in the earliest stages of the design of the database and continuing as is necessary throughout the entire process. Most performance and scalability problems are the result of poor design choices that usually can be caught and prevented early in the design process. If the problems are not addressed early on, to resolve performance issues, one may have to re-write a significant portion of the application.
When you are conducting performance tests, you should always proceed scientifically and test only one variable at a time. For instance, if you suspect that in order to increase performance you need to add an index to a table but you aren’t sure which column permutation is best, you should methodically test configuration at a time and record all execution times individually. If you don’t approach performance testing methodically, you will not be able to isolate the root of the problem. This is applicable to all aspect of performance testing including testing various hardware configurations, making SQL server configuration changes, or adding indexes.
You should always use large data sets when testing. You should also use hardware that is similar to the hardware that will be used when the application goes into production. Not doing this may result in your application failing miserably in the real production environment.
Many performance and scalability problems are not obvious. The reason for this is that many problems related to performance are not the result of a single issue but rather two or more problems. This makes it difficult and time consuming to isolate the root cause of the performance slowdown. To resolve complex performance issues one must isolate and address one problem at a time until achieving a satisfactory performance of their database application.
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