[Solved] Why does PostgreSQL require INSTEAD OF triggers to update views with joins or aggregates? — Ans: Because the database cannot automatically map updates to multiple underlying... | PostgreSQL

PostgreSQL - Views and Materialized Views

Why does PostgreSQL require INSTEAD OF triggers to update views with joins or aggregates?

ABecause aggregates require recalculating indexes.

BBecause the database cannot automatically map updates to multiple underlying tables.

CBecause INSTEAD OF triggers improve query performance.

DBecause views with joins are always read-only by design.

Step-by-Step Solution

Solution:

Step 1: Understand view update complexity
Views with joins or aggregates combine data from multiple tables or summarize data.
Step 2: Reason about update mapping
PostgreSQL cannot guess how to update multiple tables or aggregated data automatically.
Final Answer:
Because the database cannot automatically map updates to multiple underlying tables. -> Option B
Quick Check:
Complex views need triggers for update mapping [OK]

Quick Trick: Triggers map complex view updates to base tables [OK]

Common Mistakes:

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Why does PostgreSQL require INSTEAD OF triggers to update views with joins or aggregates?