How should TiDB (Database Software) balance improving query performance versus maintaining backward compatibility for existing users?

Introduction

Balancing query performance improvements with backward compatibility for TiDB presents a critical trade-off. This scenario involves weighing the benefits of enhanced database performance against the potential disruption to existing users' workflows and systems. I'll analyze this trade-off by examining the product context, stakeholder impacts, and potential strategies for resolution.

Step 1

Clarifying Questions (3 minutes)

• Based on TiDB's market position, I'm thinking this might be a critical decision for our competitive edge. Could you provide more context on our current market share and primary competitors?

Why it matters: Helps prioritize performance vs. compatibility based on competitive landscape Expected answer: TiDB has growing market share but faces stiff competition from established players Impact on approach: Would influence the urgency of performance improvements

• Considering our user base, I'm assuming we have a mix of enterprise and smaller clients. Can you break down our user segments and their typical use cases?

Why it matters: Different segments may have varying needs for performance vs. compatibility Expected answer: Diverse user base with enterprise clients more sensitive to compatibility issues Impact on approach: Would help tailor solutions to prioritize needs of key segments

• Looking at our technical roadmap, I'm curious about the scale of potential performance improvements. What percentage increase in query speed are we targeting?

Why it matters: Helps quantify the potential benefit against the risk of breaking compatibility Expected answer: Targeting 20-30% improvement in query performance Impact on approach: Would influence the cost-benefit analysis of making changes

• Regarding our development resources, I'm wondering about our capacity for supporting multiple versions. How feasible is it to maintain separate branches for performance and compatibility?

Why it matters: Affects our ability to offer flexible solutions to different user needs Expected answer: Limited resources make maintaining multiple versions challenging Impact on approach: Would push towards finding a unified solution that balances both needs

• Thinking about our release cycle, how urgent is the need for these performance improvements? Are we facing any specific deadlines or competitive pressures?

Why it matters: Helps determine the timeline for implementing changes and managing user transitions Expected answer: Aiming for significant improvements within the next two major releases Impact on approach: Would influence the aggressiveness of our performance optimization strategy