Database Rewinding with Minimal Event Retention and Time Windows
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Solution Overview
Problem
Existing database systems face challenges in efficiently managing time-based events for fast iterative rewinding, dealing with irrelevant data, conflicting data due to time paradoxes, and balancing historical data retention with storage efficiency and performance.
Innovation Solution
The system identifies and maintains relevant log records, anchor snapshots, and recovery checkpoints to reconstruct database states at different points in the past, using clock sampling records and backtracking information records to determine necessary LSN and storage offset ranges, and manages a minimum set of events within a defined backtracking window.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If comprehensive historical data is retained to support backtracking, then backtracking capability is improved, but storage size increases
Solution Approach 1:
The patent extracts only the necessary historical data (log records, anchor snapshots, recovery checkpoints) required for backtracking to a specific target timepoint, rather than retaining all historical data. The system determines relevant LSN ranges and storage offset ranges to identify precisely which data segments are needed, discarding irrelevant historical data to minimize storage overhead while maintaining backtracking capability.
Solution Approach 2:
The patent applies local quality by differentiating between relevant and irrelevant historical data based on the target timepoint. Different data segments are retained with different retention periods - data within the backtracking window is preserved, while data outside the window is discarded. This selective retention strategy optimizes storage by maintaining only the quality and quantity of historical data locally required for each backtracking operation.
2Duration of action of stationary object
If data is held for extended periods to support backtracking, then backtracking window is extended, but resource utilization decreases
Solution Approach 1:
The patent implements dynamic data retention by adjusting the backtracking window based on actual needs. The system periodically evaluates which historical data remains relevant and dynamically extends or contracts the retention period. Data is held for extended periods only when necessary to support the defined backtracking window, and discarded once no longer needed, optimizing resource utilization while maintaining the required backtracking duration.
3Measurement precision
If all historical log records are retained for reconstruction, then reconstruction accuracy is improved, but processing time increases
Solution Approach 1:
The patent applies preliminary action by pre-organizing historical data into structured formats with metadata including LSN ranges, storage offsets, and timestamps. Log records, anchor snapshots, and recovery checkpoints are预先 organized and indexed, enabling the system to quickly identify and retrieve only the relevant data segments needed for reconstruction without scanning all historical data, thus maintaining accuracy while reducing processing time.
Solution Approach 2:
The patent segments historical data into distinct units (log records, anchor snapshots, recovery checkpoints) with clear boundaries and metadata. By dividing the historical data into manageable segments organized by LSN ranges and storage offsets, the system can efficiently retrieve only the specific segments needed for reconstruction rather than processing all historical data sequentially, improving both accuracy and processing efficiency.
Data Source
AI summary
Support for distributed database backtracking, in which the database is reverted or iteratively reverted to a previous state, is provided. Log sequence number ranges and storage offset ranges for use in reconstructing the previous state are determined and used in the reconstruction. Clock sampling records can be generated indicating a feasible backtracking window with time points indicating allowable times to which backtracking can be performed. Appropriate log records, snapshots and checkpoints for database states are identified and organized with backtracking information record and timeline. A minimal and necessary set of log records, snapshots and checkpoints enabling database reconstruction within a time window is maintained. Measures are taken to maintain the necessary data to support backtracking even after prior backtrackings have occurred in the backtracking time window.