Incremental XML Tree Update via Bud-Cut Query Processing
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Solution Overview
Problem
Current techniques lack methods for incremental evaluation and maintenance of schema-directed XML views, particularly those that support recursion, which is essential for efficiently updating large XML documents in database systems.
Innovation Solution
The proposed solution involves a method and apparatus for incremental update of XML trees defined from recursive XML views of relational databases, utilizing a bud-cut approach that submits incremental queries to the database, determines changes, and applies these changes to the XML tree, minimizing recomputations and optimizing performance through caching and query merging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If full recomputation of XML views is performed when source data changes, then the XML views are kept up-to-date, but the computational overhead and response time deteriorate significantly
Solution Approach 1:
The patent segments the XML view maintenance problem by identifying and tracking only the affected portions (subtrees) of the XML document when source data changes. Instead of recomputing the entire XML view, the system divides the update task into localized subtree modifications based on change propagation analysis through the ATG rules.
Solution Approach 2:
The system performs preliminary actions by pre-computing and caching the ATG rules and their dependencies before data changes occur. When changes happen, the pre-established rule structure enables rapid identification of affected subtrees without requiring full recomputation, thus maintaining consistency while reducing update time.
2Manufacturing precision
If recursive ATG rules are used to generate XML documents, then schema conformance and document structure are ensured, but the complexity of incremental update computation increases
Solution Approach 1:
The patent introduces an intermediary layer consisting of the ATG rule system that mediates between source data changes and XML view updates. The ATG rules act as a formal grammar that systematically translates relational changes into XML subtree modifications, ensuring schema conformance while managing complexity through structured rule application rather than direct complex computation.
Solution Approach 2:
The system employs nested structures where ATG rules are organized hierarchically with parent and child rules corresponding to XML element hierarchies. This nesting allows incremental updates to propagate through the rule structure in a controlled manner, maintaining schema conformance while reducing computational complexity by only activating relevant nested rule levels.
3Speed
If cached XML documents are maintained externally by middleware, then query performance is improved, but incremental update capability is lost
Solution Approach 1:
The system implements feedback mechanisms where the middleware monitors source data changes and automatically triggers incremental update operations on cached XML documents. This feedback loop maintains the cached documents' freshness without requiring full recomputation, preserving both query performance and incremental update capability through continuous change detection and selective refinement.
Solution Approach 2:
The cached XML documents in the middleware perform self-service incremental updates by automatically detecting changes in the source database and applying the appropriate subtree modifications based on ATG rules. This self-service capability maintains document consistency without requiring external full recomputation, thus preserving both speed and adaptability.
Data Source
AI summary
Methods and apparatus are provided for incremental update of an XML tree defined from a recursive XML view of a relational database. A method comprises the steps of detecting at least one change to the relational database; providing one or more queries to the relational database to map the change to the relational database into changes to the XML tree, wherein at least one component of a definition of the one or more queries is executed a plurality of times in traversing a path through the XML tree; and applying the mapped change to the XML tree. A bud-cut method and a reduction approach are presented.