A composite index orders rows by its leading key before the next key. Compare a date-only filter, region restrictions and an isolated date-first index. Verify complete results, including new regions and NULL, before interpreting actual plans.
SQL SERVER – Execution Plan – Estimated I/O Cost – Estimated CPU Cost – No Unit
What is estimated I/O cost, what is estimated CPU cost, and why do these costs in an execution plan have no unit? I answer these common training questions.
SQL SERVER – Fix: Error: 262 : SHOWPLAN permission denied in database
My students got Msg 262, SHOWPLAN permission denied, when they tried to view an execution plan. One GRANT SHOWPLAN statement fixes it.
Finding the Slowest Statement Inside a Stored Procedure
Find the slowest statement inside a stored procedure using query stats offsets, CPU and read totals, then confirm with Query Store.
Finding Single-Use Plans Wasting Memory in the Cache
Find single-use plans, compare their cache memory with the total, and inspect parameterization before discussing server-wide cache settings.
Adaptive Joins: When the Plan Picks Its Join at Run Time
Understand adaptive joins in SQL Server, read their runtime threshold, inspect the actual choice, and test a query hint safely.
Optimize for Ad Hoc Workloads: Shrinking a Bloated Plan Cache
One-off queries can fill your plan cache with plans nobody will reuse. Here is the setting that stores a stub instead, and how to check if you need it.