Database Snapshot Management via Converter Mapping
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing database management systems face challenges in performing management tasks like integrity checks and optimizer statistics calculation without causing system downtime or performance issues, as current methods either deny client access or use locks that conflict with client requests.
Innovation Solution
The system creates a database snapshot by marking 'last known good' pages as non-overwriteable, allowing management tasks to access previous database states while maintaining system responsiveness and performance by using converter pages to map logical page numbers to physical locations and generating snapshot-specific file identifiers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If database objects are locked prior to execution of a management task, then the management task can operate on the database objects, but the locks conflict with client application requests and negatively impact system performance
Solution Approach 1:
The patent segments the database system into multiple components: the original database system, a snapshot subsystem, and a converter table. The snapshot contains a copy of database objects at a specific point in time, while the converter table maps logical page numbers to physical locations in both the original and snapshot data areas. This segmentation allows management tasks to operate on snapshots independently without locking the live database, thus maintaining system performance while enabling reliable management task execution.
2Reliability
If client applications are denied access to the database system during management task operation, then changes to database objects are prevented, but system downtime becomes unacceptable
Solution Approach 1:
The patent creates a snapshot of the database objects before executing the management task. This preliminary action captures the state of database objects at a specific point in time, allowing the management task to operate on this static copy without affecting the live database. Client applications continue to access and modify the original database objects while the management task runs independently on the snapshot, eliminating system downtime while ensuring data integrity during the management operation.
3Productivity
If the database system allows concurrent access during management tasks, then system responsiveness is maintained, but conflicts arise between management tasks and client requests
Solution Approach 1:
The patent introduces a converter table as an intermediary component that resolves conflicts between management tasks and client requests. The converter table contains mappings between logical page numbers and physical locations in both the original and snapshot data areas. When a management task needs to access a database object, the converter table directs access to the appropriate snapshot copy, preventing conflicts with client requests accessing the original database. This intermediary mechanism maintains system responsiveness while ensuring conflict-free operation.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
An executing database instance includes a first plurality of database pages associated with a previous state of the database instance, a cache storing a current converter of the executing database instance, the current converter not representing the first plurality of database pages, and a database management system. The database management system is to receive a request for access to the first plurality of database pages, and perform a database task using one or more of the first plurality of database pages while the database instance is executing.