Optimistic locking
A concurrency-control technique that detects conflicting updates by validating a version or equivalent state when changes are applied, rather than preventing concurrent access in advance.
Java Persistence with Spring Data and Hibernate epub
Optimistic locking detects conflicting concurrent modifications by checking an entity version or equivalent state rather than acquiring exclusive locks in advance.
- How it is used
- Detects conflicting changes during concurrent transactional work.
- How deep it goes
- Identifies versioning and places it in isolation-level decisions, but defers its detailed treatment.
- Examples
- Uses a diagram of two transactions updating the same data without isolation.
- What you can do after
- Evaluate/understand versioning as one consideration when choosing an isolation level for concurrent application work.
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Amazon Web Services in Action, Third Edition: An in-depth guide to AWS
Optimistic locking is a concurrency-control technique in which an update succeeds only when the item's supplied version matches its current version.
- How it is used
- Protects DynamoDB items from stale concurrent updates in a fault-tolerant web service.
- How deep it goes
- Defines version checks, walks through concurrent updates and retries, and notes overhead without detailing retry implementation.
- Examples
- Uses two processes reading version 0, one advancing to version 1, and the other retrying after rejection.
- What you can do after
- Apply it via DynamoDB conditional updates and retry rejected changes after rereading the item.
Related concepts
- concurrency controlkind of · Concurrency control coordinates simultaneous operations accessing shared state or resources to preserve correctness, consistency, and valid system behavior.
- race conditionaddresses · A race condition is a concurrency defect in which program behavior or results depend on the relative timing or ordering of interacting operations.
- consistencyaddresses · Consistency is the property of related data, behavior, outputs, or states agreeing with one another or conforming to defined rules across relevant instances or operations.
- DynamoDBuses · Amazon DynamoDB is a fully managed AWS NoSQL database service for storing and retrieving key-value and document data at scale.
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