[Solved] What does the REPEATABLE READ isolation level guarantee in PostgreSQL? — Ans: It ensures all queries in a transaction see the same data snapshot. | PostgreSQL

PostgreSQL - Transactions and Concurrency

What does the REPEATABLE READ isolation level guarantee in PostgreSQL?

AIt ensures all queries in a transaction see the same data snapshot.

BIt allows reading uncommitted changes from other transactions.

CIt locks all rows in the database for the transaction duration.

DIt automatically commits after each query in the transaction.

Step-by-Step Solution

Solution:

Step 1: Understand Repeatable Read isolation
Repeatable Read ensures that all queries in a transaction see the same snapshot of data, preventing changes made by others from appearing during the transaction.
Step 2: Compare options with definition
It ensures all queries in a transaction see the same data snapshot. matches this definition exactly. Options B, C, and D describe behaviors not related to Repeatable Read.
Final Answer:
It ensures all queries in a transaction see the same data snapshot. -> Option A
Quick Check:
Repeatable Read = Same snapshot [OK]

Quick Trick: Repeatable Read = stable snapshot during transaction [OK]

Common Mistakes:

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What does the REPEATABLE READ isolation level guarantee in PostgreSQL?