[Solved] What will the following query return?SELECT query, calls, mean_time FROM pg_stat_statements WHERE calls > 100 ORDER BY mean_time DESC LIMIT 2; | PostgreSQL

PostgreSQL - Performance Tuning

What will the following query return?

SELECT query, calls, mean_time FROM pg_stat_statements WHERE calls > 100 ORDER BY mean_time DESC LIMIT 2;

AAll queries with mean_time less than 100

BTop 2 queries with the fewest calls

CQueries executed exactly 100 times

DTop 2 slowest queries with more than 100 calls

Step-by-Step Solution

Solution:

Step 1: Understand the WHERE clause
It filters queries with more than 100 calls.
Step 2: Order by mean_time descending and limit 2
This returns the top 2 slowest queries by average execution time among those filtered.
Final Answer:
Top 2 slowest queries with more than 100 calls -> Option D
Quick Check:
WHERE calls > 100 + ORDER BY mean_time DESC LIMIT 2 = top 2 slowest frequent queries [OK]

Quick Trick: Filter by calls > 100 then order by mean_time DESC [OK]

Common Mistakes:

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What will the following query return?