Saturday, February 7, 2026
Database Query Optimization Under Load
You are tasked with optimizing a database query that is currently experiencing performance bottlenecks due to high load. The objectives are to reduce latency, increase throughput, and ensure the system can handle anticipated growth in traffic. You need to identify the root causes of the bottleneck, propose optimizations, and provide a capacity plan for scaling the system.
00The Situation
Currently, the service is experiencing average latency of 500ms, with p95 latency at 800ms and p99 latency at 1200ms. The database handles around 1000 QPS, and query execution times have been increasing due to a growing dataset. The traffic is expected to increase by 10x in the next 6 months, and the current CPU utilization is at 85% during peak times, with memory usage at 70%. You need to come up with a strategy to optimize the query performance and plan for capacity expansion.
Let's break this down step by step. How would you start?
Clarify Requirements
5 minutes
Identify the specific goals for query optimization, including acceptable latency and throughput targets, as well as growth projections.
Think about this first
What specific metrics should we focus on for optimization?
Estimate Scale
10 minutes
Calculate the required resources based on traffic growth and existing performance metrics, considering storage, throughput, and bandwidth needs.
Think about this first
What calculations would you perform to estimate the resources needed?
High-Level Architecture
15 minutes
Design a high-level architecture that addresses the performance bottlenecks and scales with the anticipated load, considering database optimization techniques, caching strategies, and load balancing.
Think about this first
How would you architect the system to handle the anticipated growth and performance issues?
Failures & Bottlenecks
10 minutes
Discuss potential failure scenarios, how they might affect system performance, and propose strategies for mitigation.
Think about this first
What failure scenarios should we consider and how would they impact performance?