I love SQL Server execution plans. It is often easy to spot the cause of a performance problem just by looking at one. The task is considerably easier if the plan includes run-time information (a so-called ‘actual’ execution plan), but even a compiled plan can be very useful. Nevertheless, there are still times where the execution plan does not ...

You probably already know that it’s important to be aware of data types when writing queries, and that implicit conversions between types can lead to poor query performance.  Some people have gone so far as to write scripts to search the plan cache for CONVERT_IMPLICIT elements, and others routinely inspect plans for that type of thing when ...

If you look up Table Hints in Books Online, you’ll find the following statement: If a clustered index exists, INDEX(0) forces a clustered index scan and INDEX(1) forces a clustered index scan or seek. If no clustered index exists, INDEX(0) forces a table scan and INDEX(1) is interpreted as an error. The interesting thing there is ...