Database Recovery Log Record Reordering for Faster Recovery
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Solution Overview
Problem
Conventional database recovery techniques require significant time and resources due to the inefficient application of log records, leading to prolonged recovery times and resource consumption, especially in large systems.
Innovation Solution
The described techniques identify and classify log records during database recovery, sorting them to eliminate the need for applying earlier records that are obviated by later records, thereby reducing the total number of records and resources needed for recovery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional database recovery techniques are used to apply all log records sequentially, then data integrity is maintained, but recovery time and resource consumption increase significantly
Solution Approach 1:
The system performs preliminary identification and classification of log records before the actual recovery process. By pre-analyzing the captured sequence of log records to identify obviating records (those that supersede earlier records), the system prepares an optimized application sequence that eliminates redundant operations during recovery, thereby reducing recovery time while maintaining data integrity
Solution Approach 2:
The invention extracts and removes obviating log records from the recovery sequence. By identifying log records that are superseded by later records (where a later record completely replaces an earlier one), the system extracts these redundant records from the recovery process, reducing the total number of records that need to be applied while preserving the essential data integrity through the remaining non-obviating records
2Reliability
If all log records are applied during recovery to ensure complete data updates, then data accuracy is maintained, but resource consumption increases
Solution Approach 1:
The system extracts and eliminates obviating log records from the recovery process. By identifying records where a later log record completely replaces an earlier one, the system removes the redundant earlier records from processing, thereby reducing CPU cycles, I/O operations, and memory usage while maintaining data accuracy through the essential non-obviating records
Solution Approach 2:
The invention discards obviating log records that are superseded by later records, recognizing that applying these redundant records would waste resources without adding value. The system recovers data accuracy by selectively applying only the non-obviating records that contain essential information, thus optimizing the balance between data accuracy and resource consumption
3Ease of operation
If log records are applied in captured sequence order, then processing simplicity is maintained, but recovery efficiency decreases due to redundant record application
Solution Approach 1:
The system performs preliminary classification of log records into obviating and non-obviating categories before the recovery process. This pre-processing step organizes the records into two distinct groups, enabling the recovery process to efficiently apply only non-obviating records while maintaining simplicity through a clear, two-stage processing approach
Solution Approach 2:
The invention extracts obviating records from the recovery sequence, creating a streamlined recovery process that applies only essential non-obviating records. This extraction creates a simpler, more efficient recovery process that maintains ease of operation by using clear classification logic while significantly improving productivity by eliminating redundant record applications
Data Source
AI summary
A captured sequence of log records for a copy of a database may be inspected to identify an obviating log record at a captured sequence position of the captured sequence and related to a page of the plurality of pages, the obviating log record corresponding to an obviating change that replaces an earlier change of an earlier log record. The captured sequence of log records may be sorted into an applied sequence of log records for applying changes of the sequence of changes, in which the obviating log record is moved from the captured sequence position to an applied sequence position that is prior to the earlier sequence position of the earlier log record. The database may then be recovered using the applied sequence of log records.