Pluggable Database Instantaneous Unplug Transport
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Solution Overview
Problem
Current database consolidation techniques face challenges in efficiently transporting databases between hosts while minimizing downtime and ensuring data consistency, particularly in container database management systems where multiple isolated databases need to be moved with minimal disruption.
Innovation Solution
The approach involves creating a hot copy of a pluggable database at a destination DBMS while allowing transactions to continue at the source DBMS, applying redo records to synchronize the database state, and using local undo logs to manage transaction changes, ensuring the database is 'pluggable-ready' for seamless integration at the destination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a database is copied using traditional shutdown methods, then data consistency is ensured, but downtime increases and productivity decreases
Solution Approach 1:
The system performs preliminary actions by creating a copy of the database at the destination before shutting down the source, and prepares the copy by applying archived redo logs in advance. This allows the database to be made available at the destination before the source is taken offline, minimizing downtime and maintaining data consistency.
Solution Approach 2:
The system maintains continuity of useful action by allowing the destination database to remain open and accepting transactions during the copy process. Archived redo logs are applied continuously to keep the copy synchronized, ensuring that the database remains available and consistent throughout the migration process.
2Productivity
If transactions are allowed to continue during database copying, then productivity is maintained, but data consistency becomes difficult to ensure
Solution Approach 1:
The system uses feedback mechanisms by applying archived redo logs to the destination database copy, which contain information about transactions that occurred at the source. This feedback process ensures that the destination copy remains synchronized with the source, maintaining data consistency even while transactions continue at the source.
Solution Approach 2:
The system creates a copy of the database at the destination and applies redo logs to this copy to maintain consistency. This copying approach allows the original database to continue processing transactions while the copy is being synchronized, resolving the contradiction between maintaining transactions and ensuring consistency.
3Adaptability or versatility
If the database is unplugged from one container and plugged into another, then adaptability is improved, but system complexity increases
Solution Approach 1:
The system segments the database into a portable pluggable database structure that can be independently moved between container databases. This segmentation allows the database to be unplugged from one container and plugged into another without affecting the container structure, improving portability while managing complexity through modular design.
Solution Approach 2:
The pluggable database structure is designed with universality, allowing the same database to be plugged into different container databases without modification. This multi-functionality enables the database to adapt to different container environments, improving versatility while the standardized interface reduces management complexity.
Data Source
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AI summary
A pluggable database is transported between a source DBMS and a destination DBMS, in a way that minimizes downtime of the pluggable database. While a copy of the pluggable database is being made at the destination DBMS, transactions continue to execute against the pluggable database at the source DBMS and change the pluggable database. Eventually, the transactions terminate or cease executing. Redo records generated for the transactions are applied to the copy of the pluggable database at the source DBMS. Undo records generated for at least some of the transactions may be stored in a separate undo log and transported to the destination DBMS. The transported pluggable database is synchronized at a destination DBMS in a "pluggable-ready state", where it may be plugged into the destination container DBMS.