KOMAL👩‍💻

Data Engineer @PwC 🇩🇪
Building in public 👩‍💻
SQL • Python • AWS • Data Engineering
Experiments, lessons, interview prep & tech thoughts

[KOMAL👩‍💻 @KomalWCode]

As a Data Engineer in Germany 🇩🇪 one thing I learned: companies care more about what you can BUILD than what you can list on a CV.

If you’re serious about Data Engineering, build these 5 projects:

Batch ETL Pipeline
Real-time Kafka Pipeline
Spark Data Processing Project
Cloud Data Warehouse
End-to-end Analytics Pipeline

5 strong projects > 50 certificates.

[KOMAL👩‍💻 @KomalWCode]

Interviewer:

YOUR DATABASE INDEX IS USED, BUT PERFORMANCE IS STILL TERRIBLE.

Index scan: 5ms. Total query: 4 seconds.

Where is the remaining time going?

[KOMAL👩‍💻 @KomalWCode]

@DeyRitoja Ek din meri last moment ki vajah se lag jayegi 😭

[KOMAL👩‍💻 @KomalWCode]

We can send 10GB files across the world in minutes.

But why do some banks still take 2–3 days to transfer money?

[KOMAL👩‍💻 @KomalWCode]

Which technology feels like pure magic?

[KOMAL👩‍💻 @KomalWCode]

Interviewer:

YOUR SQL QUERY RETURNS 1,000 ROWS IN 50ms BUT TAKES 8 SECONDS IN THE APP.

Database execution is fast. Users still wait.

Where would you investigate first?

[KOMAL👩‍💻 @KomalWCode]

We have AI that can generate a 10-page report in seconds.

But why does a printer still take 5 minutes to print it?

[KOMAL👩‍💻 @KomalWCode]

Interviewer:

YOUR SQL QUERY GOT 30X SLOWER AFTER ADDING A JOIN.

Before: 100ms. After: 3 seconds.

The joined table has only 100 rows. Why?

[KOMAL👩‍💻 @KomalWCode]

Why can a website handle 1 million visitors but crash with just 1,000 simultaneous users?

What’s the real bottleneck?

[KOMAL👩‍💻 @KomalWCode]

Interviewer:

YOUR AI MODEL’S ACCURACY IMPROVED, BUT BUSINESS LOSSES TRIPLED.

Accuracy: 94% → 99%. Same evaluation dataset.

What critical metric might accuracy be hiding?

[KOMAL👩‍💻 @KomalWCode]

What’s the most addictive technology ever?

[KOMAL👩‍💻 @KomalWCode]

Real luxuries in life ☘️🤌🏻

1. Working from home
2. Living 5 mins from the gym
3. Having quiet neighbors
4. Having money left at the end of the month
5. Peace at home

6. Drinking coffee without rushing
7. Sleeping with a clear conscience
8. Laughing with people who truly get you
9. Traveling often
10. Waking up with no alarm

11. Enjoying a home-cooked meal with loved ones
12. Having time to read a book in one sitting
13. Finding joy in daily routines
14. Having pets that greet you at the door

[KOMAL👩‍💻 @KomalWCode]

Why can adding an index make a SQL query go from 200ms to 2 seconds?

Shouldn’t indexes always make queries faster?

[KOMAL👩‍💻 @KomalWCode]

AI CAN WRITE CODE FASTER THAN YOU CAN TYPE.

Does that mean typing speed is becoming the least important skill in programming?

[KOMAL👩‍💻 @KomalWCode]

Why do software updates sometimes turn a 2-second app launch into 5 seconds?

Shouldn’t newer versions be faster?

[KOMAL👩‍💻 @KomalWCode]

Interviewer:

YOUR SQL QUERY GOT 50X SLOWER AFTER ADDING LIMIT 1.

Without LIMIT: 200ms. With LIMIT: 10 seconds.

How can fetching ONE row take longer?

[KOMAL👩‍💻 @KomalWCode]

Why can adding an index make a SQL query go from 200ms to 2 seconds?

Shouldn’t indexes always make queries faster?

[KOMAL👩‍💻 @KomalWCode]

Why can 100 concurrent users slow down an API more than 10,000 requests sent one after another?

Isn’t the total workload what matters?

[KOMAL👩‍💻 @KomalWCode]

Why does a 6-digit OTP expire in 30 seconds?

Why not 5 minutes or 10 minutes?

[KOMAL👩‍💻 @KomalWCode]

Why does a 5GHz Wi-Fi network sometimes perform worse than 2.4GHz?

Isn’t 5 supposed to be faster?

[KOMAL👩‍💻 @KomalWCode]

Interviewer:

YOUR DATABASE GOT SLOWER AFTER DOUBLING RAM.

Before: 300ms. After: 2.4 seconds.

No query changes. What would you investigate?