PostgreSQL - Transactions and Concurrency
In PostgreSQL, what happens if two concurrent transactions under SERIALIZABLE isolation try to update the same row simultaneously?
In PostgreSQL, what happens if two concurrent transactions under SERIALIZABLE isolation try to update the same row simultaneously?
medium📝 query result Q5 of 15
Step-by-Step Solution
Solution:
Step 1: Understand SERIALIZABLE isolation
SERIALIZABLE prevents concurrent conflicting updates by enforcing strict ordering.Step 2: Analyze concurrent update conflict
One transaction commits; the other fails with serialization error to avoid conflicts.Final Answer:
One transaction will succeed; the other will get a serialization failure error -> Option DQuick Check:
SERIALIZABLE = strict conflict detection [OK]
Quick Trick: Serializable aborts conflicting concurrent transactions [OK]
Common Mistakes:
- Thinking both succeed
- Assuming automatic merge
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