Evaluate Efficiency of Aggregation Operations

Analyzing Aggregation Queries with EXPLAIN ANALYZE

Write a PostgreSQL query to analyze the performance of a query that groups and aggregates data using EXPLAIN ANALYZE.

Solution:

-- Analyze the execution plan of a query that groups employees by department.
EXPLAIN ANALYZE 
SELECT department, COUNT(*) AS total_employees 
FROM Employees 
GROUP BY department;

Explanation:

• Purpose of the Query:
• To inspect the performance of aggregation and grouping operations.
• Reveals how PostgreSQL handles grouping and counting operations.
• Key Components:
• GROUP BY department : Groups data for aggregation.
• EXPLAIN ANALYZE : Provides both the query plan and actual execution times.
• Real-World Application:
• Useful when optimizing reporting queries that involve heavy aggregation.

Notes:

• Look for details on whether parallel processing is utilized in the plan.

For more Practice: Solve these Related Problems:

• Write a PostgreSQL query using EXPLAIN ANALYZE to analyze a query that groups by "department" in the "Employees" table and counts the number of employees.
• Write a PostgreSQL query using EXPLAIN ANALYZE to evaluate the performance of an aggregation query that sums "sales" in the "Sales" table, grouped by "region".
• Write a PostgreSQL query using EXPLAIN ANALYZE to display the execution plan for a query that calculates the average "price" from the "Products" table grouped by "category".
• Write a PostgreSQL query using EXPLAIN ANALYZE to analyze a query that performs multiple aggregations (SUM, AVG, COUNT) on the "Orders" table grouped by "customer_id".

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