How does PostgreSQL's default CTE materialization behavior affect query optimization in versions before 12 compared to version 12 and later?

hard📝 Application Q9 of 15

PostgreSQL - Common Table Expressions

ABefore v12, CTEs are inlined by default; from v12, always materialized

BBefore v12, CTEs are always materialized; from v12, they can be inlined by default

CCTE materialization behavior is unchanged across versions

DCTEs are deprecated in v12 and later

Step-by-Step Solution

Solution:

Step 1: Recall PostgreSQL version changes
Before version 12, CTEs were always materialized, preventing some optimizations.
Step 2: Understand v12+ behavior
From version 12, PostgreSQL can inline CTEs by default unless forced MATERIALIZED.
Final Answer:
Before v12, CTEs are always materialized; from v12, they can be inlined by default -> Option B
Quick Check:
PostgreSQL v12+ allows CTE inlining by default [OK]

Quick Trick: PostgreSQL v12+ inlines CTEs by default [OK]

Common Mistakes:

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