[Solved] Given the table users with a JSONB column preferences and a GIN index on it, what will this query return?SELECT * FROM users WHERE preferences @> '{"theme": "dark"}'; | PostgreSQL

PostgreSQL - Indexing Strategies

Given the table users with a JSONB column preferences and a GIN index on it, what will this query return?

SELECT * FROM users WHERE preferences @> '{"theme": "dark"}';

AAll rows where preferences JSONB contains key "theme" with value "dark"

BAll rows where preferences JSONB contains key "dark"

CAll rows where preferences JSONB equals exactly '{"theme": "dark"}'

DNo rows, because @> operator is invalid for JSONB

Step-by-Step Solution

Solution:

Step 1: Understand @> operator on JSONB
The @> operator checks if the left JSONB contains the right JSONB as a subset.
Step 2: Interpret the query condition
The query finds rows where preferences contain the key "theme" with value "dark" anywhere inside.
Final Answer:
All rows where preferences JSONB contains key "theme" with value "dark" -> Option A
Quick Check:
@> operator means contains = All rows where preferences JSONB contains key "theme" with value "dark" [OK]

Quick Trick: Use @> to check JSONB containment [OK]

Common Mistakes:

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Given the table users with a JSONB column preferences and a GIN index on it, what will this query return?