Resolving the Multiple Realm Clients Showing New Information While MongoDB Lags Behind

Описание: Encountering issues with Realm clients displaying updated information while MongoDB shows older data? Discover the cause and solutions to this perplexing problem in our in-depth guide.
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This video is based on the question https://stackoverflow.com/q/69018725/ asked by the user 'Akash Popat' ( https://stackoverflow.com/u/4381080/ ) and on the answer https://stackoverflow.com/a/69264088/ provided by the user 'Akash Popat' ( https://stackoverflow.com/u/4381080/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Introduction

Have you ever experienced a situation where your app's front end shows new information but the backend database still displays outdated values? This frustrating issue was recently encountered by developers working with the Realm SDK and MongoDB. They discovered that their iOS app successfully pushed updates to multiple Realm clients, which reflected the new data. However, these changes didn’t make it to MongoDB immediately, causing confusion and delays in data consistency.

In this post, we will delve into this tricky problem—how it manifested and how it was ultimately resolved. We’ll also explore potential causes and best practices to avoid similar situations in the future.

The Problem

The problem originated from a specific incident where:

An iOS app updated a document using the Realm SDK.

Thorough checks confirmed a successful upload via the forCurrentlyOutstandingWork session, indicating a 100% upload to Realm.

Multiple devices accessing the app displayed the updated information correctly.

In contrast, MongoDB displayed old data and only updated automatically after 15 minutes.

This inconsistency raised questions about the synchronization process between the backend database (MongoDB) and Realm clients.

Insights from the Community

The mentioned issue prompted queries among developers facing similar synchronization issues. Developers sought additional insights on whether this was a common occurrence or if there were underlying bugs requiring reporting.

Diagnosis and Solution

Upon reaching out to MongoDB/Realm support, it became clear that there was an underlying issue that needed addressing. The support team informed the concerned developers that a patch was made available on September 9, 2021, which resolved these synchronization problems.

Issue: Discrepancy in data updates between Realm clients and MongoDB.

Resolution: Implementation of a software update by the MongoDB/Realm support team.

Key Takeaways for Developers

Understanding Data Synchronization

Real-time Data Sync: It's essential to have an understanding of how data syncing works between systems like Realm and MongoDB, as discrepancies can cause user experience issues.

Monitoring Changes: Always monitor your backend changes using tools like logs to validate updates and ensure data integrity.

Best Practices

Version Updates: Keep your SDKs and databases updated to the latest versions to incorporate all fixes from the development team.

Logging: Use comprehensive logging mechanisms to capture what changes are uploaded, integrated, and displayed on different devices.

Community Engagement: Actively participate in communities and forums to share experiences and solutions, which can expedite finding answers to common problems.

Conclusion

In conclusion, the issue of Realm clients showing updated information while MongoDB lagged behind was a known bug that got addressed through timely support intervention. Staying informed, engaged, and proactive can help mitigate such synchronization issues. If you experience similar inconsistencies, don’t hesitate to reach out for support or consult the community for efficient solutions.

By keeping your systems—including both MongoDB and the Realm SDK—up to date and ensuring reliable monitoring of changes, you can create a smoother experience for your users across all devices.