Assess Performance of Recursive Queries with Detailed Analysis

Analyzing Recursive CTE Performance with EXPLAIN ANALYZE

Write a PostgreSQL query to analyze the execution plan of a recursive common table expression (CTE) using EXPLAIN ANALYZE.

Solution:

-- Analyze the performance of a recursive CTE that calculates a hierarchical path.
EXPLAIN ANALYZE 
WITH RECURSIVE OrgChart AS (
    SELECT employee_id, manager_id, name, 1 AS level
    FROM Employees
    WHERE manager_id IS NULL
  UNION ALL
    SELECT e.employee_id, e.manager_id, e.name, oc.level + 1
    FROM Employees e
    INNER JOIN OrgChart oc ON e.manager_id = oc.employee_id
)
SELECT * FROM OrgChart;

Explanation:

• Purpose of the Query:
• To inspect how PostgreSQL handles recursive CTEs and assess their performance.
• Useful for understanding the execution of hierarchical queries.
• Key Components:
• WITH RECURSIVE OrgChart AS (...) : Defines the recursive CTE.
• EXPLAIN ANALYZE : Executes the query and provides detailed runtime metrics..
• Real-World Application:
• Ideal for applications like organizational charts or tree structures where recursion is required.

Notes:

• Recursive queries can be complex; the plan helps identify potential performance bottlenecks and optimization areas.

For more Practice: Solve these Related Problems:

• Write a PostgreSQL query using EXPLAIN ANALYZE to evaluate a recursive CTE that generates an organizational hierarchy from the "Employees" table.
• Write a PostgreSQL query using EXPLAIN ANALYZE to analyze a recursive CTE that computes the Fibonacci sequence.
• Write a PostgreSQL query using EXPLAIN ANALYZE to assess the performance of a recursive CTE that traverses a category tree in the "Categories" table.
• Write a PostgreSQL query using EXPLAIN ANALYZE to analyze a recursive CTE that calculates the transitive closure for relationships in the "Graph" table.

Have another way to solve this solution? Contribute your code (and comments) through Disqus.

Previous PostgreSQL Exercise: Comparing Query Plans with and without Indexes.