"Getting a Plan and Reading It Right to Left"

1. What is an estimated execution plan in SQL Server?

A plan that shows the sequence of operations after executing the query. A plan that compiles the query without running it. A visual representation of the graphical plan in SSMS. A plan that automatically optimizes queries in real-time.

2. Which of the following methods is most useful for diagnosing slow queries?

Live query statistics Estimated plan Actual plan Cached plan retrieval

3. Why should you read execution plans from right to left?

Because the leftmost operator returns the final rows to the client. Data flows from the left to the right, making it easier to analyze. The rightmost operators directly access the data source, impacting performance. It follows the SQL execution order.

4. What is a key reason to use actual rows over cost percentages when analyzing a query plan?

Cost percentages are always accurate on an actual plan. Actual rows provide real performance evidence, while cost numbers are estimates. Cost percentages are a definitive measure of query efficiency. Actual rows are the only part of a plan that can be trusted.

Continue: "Estimated vs Actual, and Why Actual Matters" → Review this lesson Retake quiz