Database Recycle Bin for Object Recovery Without Shutdown
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Solution Overview
Problem
Current database systems require database shutdown during the retrieval of purged objects due to time-consuming rollback and rollforward processes, which prevents new transactions from being executed.
Innovation Solution
Implementing a recycle bin mechanism where objects and dependent objects are moved to a repository upon a drop command, allowing for fast retrieval without shutting down the database by moving them back out when needed, and purging objects to reclaim storage space as required.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If database rollback and rollforward is used to retrieve purged objects, then objects can be retrieved, but database shutdown is required and new transactions cannot be executed
Solution Approach 1:
The patent divides the database object lifecycle into distinct segments: active state, recycle bin state, and purged state. Objects are moved to a recycle bin rather than permanently deleted, allowing retrieval without full database rollback. This segmentation enables object recovery while maintaining database availability for new transactions.
Solution Approach 2:
The recycle bin serves as an intermediary repository between the active database and permanent deletion. Objects temporarily stored in the recycle bin can be restored without requiring database shutdown, acting as a buffer that enables retrieval operations while maintaining system availability.
2Reliability
If database rollback is performed to retrieve purged objects, then objects can be retrieved, but the process is time consuming
Solution Approach 1:
Objects are moved to the recycle bin immediately upon drop, preserving their state before permanent deletion. This preliminary action allows rapid retrieval by simply moving objects from the recycle bin back to the active database, avoiding time-consuming rollback operations.
Solution Approach 2:
The recycle bin creates a logical copy of dropped objects, maintaining their state and metadata. This copy enables fast retrieval operations without requiring reconstruction or rollback, significantly reducing retrieval time compared to traditional methods.
3Quantity of substance
If objects are permanently deleted to free storage space, then storage space is reclaimed, but object retrieval is no longer possible
Solution Approach 1:
The recycle bin implements a temporary discarding mechanism where objects are moved rather than permanently deleted. This allows objects to be recovered from the recycle bin if needed, while still freeing storage space in the active database. The system balances space reclamation with retrieval capability.
Solution Approach 2:
The patent introduces dynamic object status management where objects can transition between active, recycled, and purged states. This dynamic approach allows the system to adapt between space reclamation mode and object retrieval mode, providing flexibility in managing storage and data availability.
Data Source
AI summary
Techniques for undropping objects (e.g., tables) and dependent objects in a database systems are provided. When an object is dropped, the object is moved to a recycle bin where it resides until the user undrops the objects or the object is purged. Dependent objects are also moved into the recycle bin with the object to which they depend. The object can be purged from the recycle bin explicitly by a user or when more storage space is needed. Purging of dependent objects and partitions can be deferred if not required to obtain more storage space.