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Amazon DynamoDB Unlocked (2025): Mastering Core Components ...
Excerpt
3. **Pitfall: Misunderstanding Consistency Models.** - **Problem:** Not realizing that reads from GSIs and default table reads are eventually consistent. This can lead to stale data if an immediate read follows a write. - **Best Practice:** Understand the trade-offs. For reads that require absolute up-to-date data, use strongly consistent reads on the base table (doubles RCU cost). For GSIs, design your application to tolerate eventual consistency or implement read-after-write patterns with retries/delays if strong consistency is critical on GSI data. 4. **Pitfall: Over/Under-provisioning Capacity (Provisioned Mode).** - **Problem:** Setting RCUs/WCUs too low leads to throttling and errors. Setting them too high wastes money. - **Best Practice:** Monitor `Consumed*CapacityUnits` and `ThrottledRequests` metrics in CloudWatch. Implement DynamoDB Auto Scaling to adjust provisioned capacity automatically based on demand. Consider On-Demand mode if workloads are highly unpredictable. … - **Problem:** Applying relational database design principles (multiple normalized tables) directly to DynamoDB can lead to many tables and complex application-side joins, negating NoSQL benefits. - **Best Practice:** For simple use cases, separate tables are fine. For complex, related data, explore **Single Table Design (STD)**. This involves storing different but related entity types in a single table, using generic primary key attributes (e.g., `PK`, `SK`) and GSIs to model one-to-many and many-to-many relationships. This is an advanced topic but incredibly powerful.
Related Pain Points
MongoDB eventual consistency breaks real-time data accuracy
7MongoDB uses eventual consistency for replica sets, which can cause situations where different users read different data at the same time. Applications requiring strong consistency and real-time data accuracy face serious issues.
Unpredictable and difficult cost management
6DynamoDB's on-demand pricing model can lead to unexpected expenses with variable workloads. Provisioned mode requires careful capacity planning to avoid throttling or waste, and cost monitoring is complex without proper tooling configuration.