[Solved] How can you modify a recursive CTE to prevent infinite loops caused by cycles in hierarchical data? — Ans: Add a path tracking column and filter out rows already visited in recursion | PostgreSQL

PostgreSQL - Common Table Expressions

How can you modify a recursive CTE to prevent infinite loops caused by cycles in hierarchical data?

ARemove the anchor member to stop recursion

BReplace UNION ALL with UNION to remove duplicates

CAdd a path tracking column and filter out rows already visited in recursion

DUse a LIMIT clause inside the recursive part

Step-by-Step Solution

Solution:

Step 1: Understand cycle prevention
Tracking visited nodes (e.g., with a path array) helps detect and skip cycles during recursion.
Step 2: Evaluate other options
Replacing UNION ALL with UNION does not prevent cycles, removing anchor stops recursion, LIMIT only limits rows but not cycles.
Final Answer:
Add a path tracking column and filter out rows already visited in recursion -> Option C
Quick Check:
Track visited nodes to avoid cycles [OK]

Quick Trick: Track visited nodes to stop cycles in recursion [OK]

Common Mistakes:

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How can you modify a recursive CTE to prevent infinite loops caused by cycles in hierarchical data?