Given the query EXPLAIN ANALYZE SELECT * FROM orders WHERE order_id = 10;, which part of the output tells you how many rows were actually returned?

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PostgreSQL - Performance Tuning

Given the query EXPLAIN ANALYZE SELECT * FROM orders WHERE order_id = 10;, which part of the output tells you how many rows were actually returned?

AThe "Buffers" section

BThe "Estimated Rows" value in the output

CThe "Planning Time" value

DThe "Actual Rows" value in the output

Step-by-Step Solution

Solution:

Step 1: Understand EXPLAIN ANALYZE output fields
"Actual Rows" shows the real number of rows returned by each step during execution.
Step 2: Differentiate from other fields
"Estimated Rows" is the planner's guess before running. "Planning Time" is time spent planning. "Buffers" shows disk usage, not row count.
Final Answer:
The "Actual Rows" value in the output -> Option D
Quick Check:
Actual Rows = real returned rows [OK]

Quick Trick: "Actual Rows" shows real returned rows, not estimates [OK]

Common Mistakes:

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