技术/技能面试

Good morning, thanks for coming in today. Let's start with a technical question. Can you walk me through the process of optimizing a database query for performance?

Good morning. Of course. Typically, I'd begin by analyzing the current query execution plan using `EXPLAIN`. This helps identify bottlenecks like full table scans or inefficient joins. From there, I'd consider adding appropriate indexes, rewriting complex subqueries, and ensuring proper normalization.

Excellent. What if indexing isn't sufficient? Are there any other strategies you'd employ to improve query speed?

Definitely. Beyond indexing, I'd look into denormalization for read-heavy tables, especially if joins are causing significant overhead. Caching frequently accessed data at the application layer or using a dedicated caching system like Redis or Memcached can also drastically improve response times. Lastly, optimizing server configuration, such as increasing RAM or adjusting buffer sizes, plays a role.

That's a comprehensive answer. Now, let's move on to a practical scenario. Imagine you're presented with a bug report where an application is experiencing slow load times on a specific page. How would you approach debugging this, assuming you suspect a frontend performance issue?

I'd start by using browser developer tools, specifically the Network and Performance tabs. The Network tab would help identify large assets, slow API calls, or excessive requests. The Performance tab would allow me to record a session to analyze CPU usage, rendering bottlenecks, and long-running scripts.

And once you've identified a potential bottleneck, what are some common frontend optimizations you'd consider implementing?

Common optimizations include image optimization and lazy loading, minifying and compressing CSS/JavaScript files, debouncing or throttling expensive event handlers, and leveraging browser caching through proper HTTP headers. If it's a JavaScript-heavy application, code splitting and tree shaking can also be very effective.

Excellent. That's a solid approach. Thank you for your detailed responses.

You're welcome. I appreciate the opportunity.