Database Sequence Replication via Log Reader Module
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Solution Overview
Problem
Database replication systems face challenges in replicating Oracle sequences effectively, particularly due to issues with cached sequence values being lost or skipped, which can lead to gaps and inconsistencies across multiple sites, especially in standby implementations where a precise replica is crucial.
Innovation Solution
A replication system that monitors changes to table data in the primary database, logs these changes, and applies them to a replicate database to reconstruct and maintain identical sequence objects, using a log reader module to ensure accurate replication of sequence objects across sites.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If database replication is implemented to ensure data availability and consistency across sites, then data reliability is improved, but sequence object replication becomes complex due to cached values being lost or skipped
Solution Approach 1:
The patent introduces an intermediary mechanism (log reader module and replication system) that mediates between the primary database and replicate database to handle sequence object replication. This intermediary captures sequence generation events through logging and applies them to the replicate database, resolving the complexity of directly replicating cached sequence values while maintaining data reliability across sites
Solution Approach 2:
The patent implements preliminary action by logging sequence generation events at the primary database before they are replicated to the replicate database. The log reader module reads these pre-captured events and applies them to the replicate database, ensuring that sequence objects are replicated accurately without the complexity of handling cached value losses or skips during the replication process
2Stability of the object's composition
If sequence objects are replicated to standby databases to maintain consistency, then data consistency is improved, but gaps and inconsistencies occur due to cached sequence values being lost or skipped
Solution Approach 1:
The patent implements feedback by having the log reader module continuously monitor and read sequence generation events from the primary database log, then apply these events to the replicate database. This feedback mechanism ensures that the replicate database receives accurate sequence value information, preventing gaps and inconsistencies that would otherwise occur due to cached value losses or skips
Solution Approach 2:
The patent uses copying by creating a replicate database that is a precise copy of the primary database, including sequence objects. The log reader module copies sequence generation events from the primary database log and applies them to the replicate database, ensuring that the replicate database maintains data consistency without suffering from cached sequence value losses or skips
3Measurement precision
If log reading is implemented to capture sequence changes, then replication accuracy is improved, but processing time increases due to monitoring and applying log changes
Solution Approach 1:
The patent implements continuity of useful action by having the log reader module continuously monitor and read sequence generation events from the primary database log in real-time. This continuous operation ensures that sequence changes are captured accurately and applied to the replicate database without interruption, maintaining high replication accuracy while minimizing processing delays through efficient continuous log reading
Data Source
AI summary
Replication system with methodology for replicating database sequences is described. In one embodiment, for example, in a database system, a method of the present invention is described for replicating a sequence object from a primary database to a replicate database, the method comprises steps of: monitoring changes to table data at the primary database for capturing information sufficiently characterizing the sequence object to allow its replication, the table data being logged to a log file; reading the log file, for determining changes to apply to the replicate database for replicating the sequence object; and reconstructing the sequence object at the replicate database based on the determined changes.