Why might a GIN index on a JSONB column not improve performance for queries checking for existence of a single key?

hard📝 Conceptual Q10 of 15

PostgreSQL - Indexing Strategies

ABecause PostgreSQL disables GIN indexes for small tables

BBecause JSONB columns cannot be indexed for key existence

CBecause GIN indexes only work on arrays, not JSONB

DBecause GIN indexes are optimized for containment, not simple key existence

Step-by-Step Solution

Solution:

Step 1: Understand GIN index optimization
GIN indexes are optimized for containment queries (like @>), not for simple key existence checks.
Step 2: Analyze why performance may not improve
Existence checks may require scanning or different index types; GIN may not help much for single key existence.
Final Answer:
Because GIN indexes are optimized for containment, not simple key existence -> Option D
Quick Check:
GIN best for containment, not key existence = Because GIN indexes are optimized for containment, not simple key existence [OK]

Quick Trick: GIN excels at containment, not single key existence checks [OK]

Common Mistakes:

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