Database Recovery with Dynamic Volume Catalog
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Solution Overview
Problem
Database recovery processes face challenges in selecting appropriate log backups due to the existence of multiple log sequences and volume management, especially when volumes are added or removed during operation, leading to inconsistencies in restoring the database to a specific point in time.
Innovation Solution
A backup catalog system is implemented to manage data and log backups independently for each volume, associating them with unique identifiers and timestamps, allowing for accurate selection and recovery of log backups based on specified points in time, even when volumes are dynamically added or removed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If log backups are selected from multiple log sequences after volume changes, then the database can be recovered to a specified point in time, but selecting the correct log backups becomes difficult and error-prone
Solution Approach 1:
The patent introduces a backup catalog as an intermediary data structure that tracks and manages log backup information across multiple volumes and log sequences. The catalog stores metadata including volume identifiers, log sequence numbers, and timestamps, allowing the recovery process to automatically identify the correct log backups without manual selection. This intermediary resolves the contradiction by making the complex selection process transparent and automated.
Solution Approach 2:
The system implements feedback mechanisms where the backup catalog continuously updates with information about volume changes, log sequence transitions, and backup operations. During recovery, the system uses this feedback information to automatically determine which log backups are needed, eliminating manual selection errors and ensuring consistent recovery even after volumes are added or removed.
2Adaptability or versatility
If volumes are dynamically added or removed during database operation, then the database system is more flexible and adaptable, but maintaining consistent database state across volumes becomes more complex
Solution Approach 1:
The patent segments the backup management system by volume, creating independent backup catalogs for each volume while maintaining a global view through parent-child relationships. Each volume's backup operations are managed independently, allowing volumes to be added or removed without affecting others. The segmentation is reflected in the catalog structure where each volume has its own backup records but links to the global database state through consistent timestamps and log sequences.
Solution Approach 2:
The patent adds a new dimension to volume management by introducing volume identifiers and hierarchical relationships in the backup catalog. Instead of treating volumes as a flat set, the system organizes them in a hierarchical structure with parent-child relationships, allowing dynamic addition and removal while maintaining global consistency. This dimensional organization enables flexible volume management without compromising backup integrity.
3Ease of manufacture
If separate data backups and log backups are generated for each volume independently, then backup operations are simpler and more modular, but selecting backups that result in a consistent overall database state becomes difficult
Solution Approach 1:
The patent merges the independent volume-level backup catalogs into a unified recovery selection process. While backups are generated independently for each volume (maintaining simplicity), the backup catalog structure combines information from all volumes, including cross-volume dependencies and consistency requirements. During recovery, the system merges this information to select a consistent set of backups across all volumes, ensuring database state consistency while preserving the simplicity of independent backup generation.
Data Source
AI summary
A system includes reception of a command to recover a database to a point in time, determining a log backup which covers the point in time, determination of a sequence identifier associated with the log backup, collection of log backups which are older than the determined log backup and associated with the sequence identifier, and a data backup associated with the sequence identifier, and execution of a recovery of the database based on the determined log backup and the collected log backups and data backup.