Tausif May 13, 2025

 

Schema for Restoring Consistency in Mobile Database Systems

Mobile database systems often face challenges like intermittent connectivity, limited bandwidth, frequent disconnections, and resource constraints. These issues can lead to inconsistent data states between mobile hosts (MHs) and central databases (fixed hosts or servers). To overcome this, a consistency restoration schema is used to ensure the correctness and reliability of data.

Here’s a structured schema for restoring consistency in mobile database systems:

1. Conflict Detection

Before restoring consistency, the system must identify whether any data conflicts have occurred. This is typically done during:

  • Reconnection after disconnection.

  • Data synchronization between the mobile device and server.

Techniques used:

  • Timestamp comparison.

  • Versioning.

  • Operation logs.

2. Conflict Resolution

Once a conflict is detected, the system applies rules or policies to resolve it. Common conflict resolution strategies include:

  • Last Update Wins – The most recent change is retained.

  • Server Wins/Mobile Wins – One side is prioritized over the other.

  • Merge Policies – Custom logic to combine data (e.g., for calendars or notes).

  • User Intervention – Prompting the user to choose the correct version.

3. Data Synchronization

After resolving conflicts, data is synchronized between the mobile and fixed databases. This involves:

  • Uploading updates from the MH to the server.

  • Downloading updates from the server to the MH.

  • Ensuring ACID properties are respected during synchronization.

4. Transaction Reconciliation

Incomplete or failed transactions are rolled back or re-executed to ensure consistency. This step may use:

  • Mobile Agents.

  • Tentative Transactions that commit only after reconnection.

Conclusion

The schema for restoring consistency in mobile databases involves a systematic process of conflict detection, resolution, synchronization, and transaction reconciliation. It ensures data integrity, reliability, and seamless user experience despite the challenges of mobility.

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