Unified Framework for Global Table Replica Data Freshness

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Solution Overview

Problem

Existing databases lack flexibility and efficiency in providing multiple levels of database support, particularly in accommodating different levels of data freshness and disaster recovery requirements, often resulting in inadequate service and potential data disruption during operations like moving data between Paxos/RAFT groups.

Innovation Solution

A unified framework for a distributed database that allows for different levels of database support by using policies based on flushed log sequence numbers (LSN), applied LSN, and transaction timestamps to manage transactions across replica nodes, enabling efficient switching between support levels without bulk data movement and ensuring data freshness and availability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If data is moved between Paxos/RAFT groups to change database support levels, then database support flexibility is improved, but data availability and service continuity deteriorate due to substantial copying operations and potential data non-availability

Engineering Contradiction:
Improvedatabase support flexibilityVSAvoiddata availability
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The system segments database support levels into distinct policies (first policy, second policy, etc.) that can be independently applied to different tables. Each policy defines specific requirements for transaction commitment based on replica node status, allowing flexible configuration without moving data between groups.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent creates a universal framework where a single Paxos/RAFT group can serve multiple database support levels through policy configuration. The primary node can manage multiple tables with different policies within the same group, eliminating the need for separate groups for different support levels.

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Adaptability or versatility

If multiple Paxos/RAFT groups are used to provide different database support levels, then service quality is improved, but system complexity and operational overhead worsen due to managing multiple groups and data copying

Engineering Contradiction:
Improvemultiple support levelsVSAvoidsystem complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent merges multiple database support levels into a single Paxos/RAFT group by implementing policy-based management. Different tables within the same group can have different policies applied, combining the functionality of multiple groups while reducing system complexity and eliminating data copying operations.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The system implements dynamic policy assignment where tables can be assigned to different database support policies without structural changes to the Paxos/RAFT group. Policies can be modified, added, or removed dynamically through metadata updates, allowing flexible adaptation without system reconfiguration.

Inventive Principle:
Principle #15Dynamics

3Reliability

If strict data freshness guarantees are implemented across all replica nodes, then data consistency is improved, but transaction commit speed and system performance worsen due to waiting for all replicas to catch up

Engineering Contradiction:
Improvedata consistencyVSAvoidtransaction commit speed
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The patent applies different freshness guarantee requirements to different tables based on their specific needs. Critical tables can have strict consistency requirements (waiting for all replicas), while non-critical tables can tolerate looser consistency (faster commit). Each table's policy is customized to its local quality requirements.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The system changes the consistency parameter dynamically based on policy configuration. Policies define different thresholds for replica synchronization (e.g., flushed LSN, applied LSN, transaction timestamps), allowing the system to adjust the strictness of consistency guarantees to optimize between data consistency and transaction commit speed.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentUS20240028580A1Methods and systems related to a unified framework for global table with guarantee on replica data freshness
Publication Date: 2024.01.25 HUAWEI TECH CO LTD
  • US20240028580A1 patent drawing
  • US20240028580A1 patent drawing
  • US20240028580A1 patent drawing

AI summary

The present disclosure provides for methods and systems related to a unified framework for global table with guarantee on replica data freshness. According to a first aspect, a method is provided. The method includes receiving a first transaction for updating a first table and a second transaction for updating a second table. The first and the second table being respectively associated with a first and second policy. The method further includes generating a first queue indicating the first transaction and a second queue indicating the second transaction. The method further includes receiving from a set of replica nodes information indicating a status of each replica with respect to the first transaction and the second transaction. The method further includes determining that at least one of policies is satisfied based on the received information and committing one of the transactions based on the determining