This post is the first in a series about physical join operators,
please be sure to check out:
I thought to jump directly to talk about the physical operators, but I do believe this series deserve a good foundation.
The confession.
Some time ago, I interviewed at a well-known tech company for a position that seemed to be my dream job, the responsibilities for this position were a perfect match (60 % SQL Developer and 40% .NET Developer). During the interview, they asked a bunch of technical questions about .NET, web services and other stuff but nothing related to SQL Server.
After several hours of interviewing with several different people, the Head of Development came into the conference room, he told me that DBA team is working on some urgent stuff and they are not able to finalize the interview that day, but he would like to schedule a phone call to finalize the interview, I agreed and left the place with a piece of paper that somebody handed to me, it was the schedule for final interview.
The three questions.
Next day, DBA Team called me, they apologized for previous day, one of the DBAs told me that in compensation they only have three questions for me, I smiled and agreed (I was thinking “easy peasy lemon squeezy”)… I was so wrong and I will never forget the two questions they asked me, yes two since I did not make it to the third one.
Please see below and try to do not laugh too loud =P.
DBA: Are scans bad? Question #1
Silly Victor: It depends! Yes I used that one and worked like charm, but I did not know the answer.
DBA: Yes, I depends.
DBA: What are the three physical join operators? Question #2
Silly Victor: Three?
DBA: Yes, three.
Silly Victor: Inner Join…
DBA: Physical join operators!
Silly Victor: Left Join…
DBA: Thank you Victor, that’s all the questions that I have for you. Do you have any questions for me?
Silly Victor: No, thank you.
Postmortem.
How did I feel after all?
A bad interview can leave you feeling frustrated and upset, I truly was very upset and angry with myself, but this was nothing compared to how stupid I felt that day.
Why do I failed?
Because I was not humble, I thought that since I was able to write complex queries, I had mastered SQL Server.
Can I fix it?
No, we cannot change the past, but we can prevent it in the near future.
What was the third question?
I have no idea and I am not sure if I am ready to answer that one, but I am doing my best every day.
Conclusions.
Be humble and help others as much as you can.
If you don’t know the answer, please do not try to make up stuff, is better to said something like “I don’t know, but I am willing to learn”
Never give up, no matter how you feel, please never give up.
Keep learning, you never stop learning.
SQL Server is kind of Science.
I promise that in next series I am going to talk about Nested Loop Join.
Enjoy!!
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