Correcting errors/root cause analysis

Mistakes happen, that is normal and perfectly acceptable.

The same mistake happening again is not acceptable.

There are many well established techniques for preventing the same mistake happening again. I like the sites below. Remember these key points

• Processes fail, not people.
• back to standard fixes are just fire fighting. e.g. fix a puncture
• improving the standard is what you want. e.g. puncture proof tyres, new route with less debris.

SQL server cached plans

If you are using OpenQuery or sp_execute_sql a lot then your server is probably loaded with cached execution plans, for adhoc queries that will never be used again.

These two grate blogs deal with the issue nicely
http://sqlmag.com/database-performance-tuning/sql-server-plan-cache-junk-drawer-your-queries 
http://www.sqlskills.com/blogs/kimberly/plan-cache-and-optimizing-for-adhoc-workloads/