11 Mistakes To Avoid On A Technical Interview

You’re in for a technical interview. They ask you a question, and you have to build a system or to write some code, either on a whiteboard (brr!), on a piece of paper, or on a laptop at home. And then you discuss it with the interviewer.

Some enjoy it, and some dread it. But if you are going through it, it means the end of the process is near! And you really want to show the best side of yourself.

I led more than 120 interviews. Here are some common mistakes I noticed the candidates make.

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Unit testing: best practices

I have been unit testing my code for many years.

While building a GIS-system, we really cared about our product quality. Our users’ needs demanded the app to work properly. I had all critical and/or complex parts of code 100% test-covered, with multiple paths and corner cases. It was such a pleasure to find a bug, fix it, write a couple of tests for this surprise scenario, and be sure it won’t break again. Ah, good times.

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Seeing The Big Picture: One Important Aspect Of Being A Senior Developer

Many developers tell what they have done. They used Kafka, RabbitMQ and Kubernetes. They sharded, scaled and clustered. They moved the logic from monoliths to microservices. They built castles and teared down mountains.
What they often don’t say is why they did it.

I often ask this question on interviews:

“What is the most interesting or challenging task you have ever done?”

The answer tells me a lot.

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Little Geo Stories: Square Miles

How I sensed a bug while not seeing any, and what came of it.

Dear reader,

Today I found a place on our website where we display the size of a recreational area in square kilometers.

199 km²

I cannot fully explain what happened next, but I had a hunch something must be wrong with this feature.

Narrator: there was.

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Little Geo Stories: A Tale Of 180th Meridian

A little story about a very common mistake when working with Earth coordinates around 180th meridiane.

Several days ago, I got a bug request: no airports around a certain hotel were being displayed.

There certainly were some airports relatively close to the hotel, and judging by all conditions they should have been there. This hotel’s page could boast with very good air connections, but it did not.

Like a proper seasoned Geo-expert should do in this case, first thing I did – was checking the location of the hotel.

Of course, it was located on Fiji.

The problem immediately became absolutely clear to me.

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A/B testing: introduction

I’ve been running A/B tests for 2 years now, and during this time I have run more than 300 experiments.
I will share with you my knowledge: I will explain what A/B testing is, when do you need it (and when you don’t), and how to utilize it to the greatest extent.

This article is based on my conference talk about A/B testing – check out the slides.

What is A/B testing, anyway?

Let’s imagine you own a webpage for selling flowers, and you have a red “buy” button in there.

Now let’s imagine your new designer tells you: hey, green buttons are a new trend in the flower selling industry. People like green more than red, red is aggressive, green is soft and persuading. Green button will be more visible on the page. Let’s make it green.

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