Migrating Temporary Session Data via External Tables
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Solution Overview
Problem
Current testing approaches for database systems fail to accurately replicate the real-world workload of production systems, leading to inadequate validation of changes before they are implemented in production, particularly due to the loss of temporary data when sessions are terminated.
Innovation Solution
A method for migrating temporary data from one session to another, including the creation of an external table for storing temporary data in a separate storage container and providing location information to the second session process, ensuring that all session state is preserved and accessible during migration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If session state is stored in temporary segment on disk, then session data can be preserved beyond memory, but data is lost when session terminates and cannot be migrated
Solution Approach 1:
The patent extracts temporary data from the session-specific temporary segment and stores it in a separate, persistent location (such as a permanent table or external storage). This separation allows the data to be preserved independently of the session lifecycle, enabling migration to new sessions while the original session terminates.
Solution Approach 2:
The patent performs preliminary action by migrating temporary data to a persistent storage location before the session terminates. This ensures that when the session ends and temporary data would normally be lost, the data has already been safely transferred to a location that can be accessed by new sessions.
2Adaptability or versatility
If traditional session migration is performed, then session state can be transferred, but temporary data stored on disk is not included and is lost
Solution Approach 1:
The patent creates a universal storage mechanism that serves multiple functions: it stores temporary data during active sessions, preserves it across session boundaries, and enables migration to new sessions. This multi-functional approach allows the same data storage infrastructure to support both traditional and persistent temporary data requirements.
Solution Approach 2:
The patent introduces an intermediary storage layer (such as a permanent table or external storage system) that acts as a mediator between the temporary segment and new sessions. This intermediary receives temporary data from terminating sessions and makes it available to new sessions, enabling seamless migration without direct session-to-session transfer.
3Reliability
If workload is replicated from production to test system, then realistic testing can be performed, but temporary data is lost when test sessions terminate
Solution Approach 1:
The patent implements a copying mechanism where temporary data from production sessions is copied to persistent storage, and then copied again to test sessions. This multi-stage copying ensures that temporary data survives the session lifecycle in both production and test environments, maintaining workload replication accuracy throughout the testing process.
Data Source
AI summary
A technique for migrating (e.g., “copying” or “moving”) temporary data from one session to another session is provided. While executing a workload associated with a particular session, session state is created. A subset of the session state comprises large objects that are referred to as “temporary data.” Thus, temporary data is stored in a database (instead of in the database server) and is normally deleted when the particular session is deleted. To avoid this deletion when the session state is migrated to a different session, the temporary data, in one embodiment, is saved in an external storage that is separate from the database. An external table is created in the external storage and stores the temporary data. Location information to access the external table is provided to the other session.