In-Place XML Schema Evolution for Database Compatibility
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Solution Overview
Problem
Copy-based evolution in XML schema management is resource-intensive and time-consuming, particularly in large database systems, as it requires backing up, transforming, and restoring entire XML documents, even for minimal changes, leading to long downtimes and increased complexity in storage operations.
Innovation Solution
The implementation of in-place XML schema evolution mechanisms that evaluate compatibility between existing and new schemas, allowing for backward compatible changes without requiring the entire dataset to be transformed, and maintaining document ordering by updating mapping information on disk, thereby reducing resource usage and execution time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If copy-based evolution is used to update XML schema, then the schema can be updated to maintain compatibility with changed client applications, but the entire set of XML documents must be backed up, transformed, and restored even for minimal changes, leading to long downtimes and high resource consumption
Solution Approach 1:
The patent segments the XML document data into two parts: conforming documents that match the new schema and non-conforming documents that require transformation. Instead of copying and transforming the entire dataset, only the non-conforming segment is processed. This is achieved by evaluating each document against the new schema and applying transformation only where necessary, thereby reducing downtime and resource consumption while maintaining schema update capability.
2Adaptability or versatility
If copy-based evolution is used to update XML schema, then the schema can be updated, but the entire set of XML documents must be transformed and copied into memory before inserting new information, making the transformation process time-consuming
Solution Approach 1:
The patent applies partial action by transforming only the portion of XML documents that are non-conforming to the new schema, rather than transforming the entire dataset. The system evaluates each document against the new schema and applies transformation selectively. This partial transformation approach significantly improves productivity by avoiding unnecessary copying and transformation of already conforming documents, while still achieving complete schema evolution.
3Adaptability or versatility
If copy-based evolution is used, then XML documents can be transformed to conform to the new schema, but the documents must be copied as a whole back into the updated database, increasing complexity in storage operations
Solution Approach 1:
The patent extracts only the necessary transformation operations from the complete copy-based evolution process. Instead of copying entire documents back into the database, the system extracts and applies only the minimal changes needed to make non-conforming documents conform to the new schema. This extraction approach simplifies storage operations by eliminating unnecessary data movement while maintaining schema compatibility.
Data Source
AI summary
In-place XML schema evolution occurs by evaluating an existing XML schema in a database system to see if it is compatible with a new XML schema. To determine if the old schema is compatible with the new schema, a lock-step traversal is performed on the two schemas. Each instruction in the old schema is compared to instructions in the new schema. Detected differences between the two schemas are evaluated to determine if existing XML documents are still compatible with the new schema. If they are, then an in-place schema evolution operation can take place. The in-place schema operation basically, involves appending the updated object information to the underlying object type and preserving the order of elements in a document by storing element mapping information on disk.