A developer sets the isolation level using: SET TRANSACTION ISOLATION LEVEL SERIALIZABLE; but still observes phantom reads. What is the most likely cause?

medium📝 Debug Q6 of 15

SQL - Transactions and Data Integrity

AThe command was run outside a transaction

BThe database does not support SERIALIZABLE level

CThe isolation level was set after the transaction started

DPhantom reads are allowed in SERIALIZABLE level

Step-by-Step Solution

Solution:

Step 1: Understand when isolation level applies
Isolation level must be set before transaction begins to take effect.
Step 2: Analyze phantom reads despite SERIALIZABLE
If set after start, previous level remains, allowing phantoms.
Final Answer:
The isolation level was set after the transaction started -> Option C
Quick Check:
Set isolation before transaction starts [OK]

Quick Trick: Set isolation level before starting transaction [OK]

Common Mistakes:

Assuming phantom reads allowed in SERIALIZABLE
Ignoring transaction boundaries

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More SQL Quizzes

A developer sets the isolation level using: SET TRANSACTION ISOLATION LEVEL SERIALIZABLE; but still observes phantom reads. What is the most likely cause?

Step 1: Understand when isolation level applies

Step 2: Analyze phantom reads despite SERIALIZABLE

Final Answer:

Quick Check:

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