Improve an application performance by adding indexes to a database

Question

I\'ve got an old web application with a lot of legacy code and I need to improve performance for some reports. I want to avoid reports rewrite, because it\'s standard legacy app

Answer 1

1. It's a good idea to improve application performance by improving SQL queries performance if DB is a bottleneck. From information provided above I can say that in your case DB performance is important and worth to improve.

2. It's possible to significantly improve performance of reports which execute a lot of queries by adding indexes. Especially if tables itself contain tons of records (10 000 and more). But, indexes have their own drawbacks:

   • they slowdown insertions/updates/deletions
   • they influence query execution plan. As a result in some cases DB manager chooses to use index when it would be more appropriate to perform full table scan. Which in turn causes performance degradation.