Answer
Pessimistic uses locks to avoid conflicts. Optimistic uses row versioning to detect conflicts at commit without blocking readers.
Quick Answer
Pessimistic concurrency uses locks upfront — a transaction locks data before reading or writing to prevent conflicts. Optimistic concurrency assumes conflicts are rare — it reads without locking and checks at commit time if someone else changed the data. SQL Server supports both via isolation levels and snapshot isolation.
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SugharaIQ Editorial Team
Verified Answer
This answer has been peer-reviewed by industry experts holding senior engineering roles to ensure technical accuracy and relevance for modern interview standards.
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Source: SugharaIQ