Explaining a query plan starts with the costly work, checks estimates against actual rows, and turns findings into a clear code decision.
SQL SERVER – Actual Execution Plan vs. Estimated Execution Plan
Actual Execution Plan or Estimated Execution Plan? I always use the actual plan because it is accurate. Shortcuts: CTRL+M for actual, CTRL+L for estimated.
Memory Grants: Why a Query Waits for Memory
Memory grants can leave SQL Server queries waiting on RESOURCE_SEMAPHORE; inspect estimates, grants, and spills before adding memory.