7 ms·

Well, I need to interview candidates because I need to know if they are up for the job when systems breaks. If a table query fails because it needs a btree inde

by TeeWEE 13y ago

Well, I need to interview candidates because I need to know if they are up for the job when systems breaks. If a table query fails because it needs a btree index due to range searches, I want the candidate to know how a btree index works and why it fixes the issue. Also If somebody cant tell me the difference between http udp and tcp, its a no hire for me. So for me, I really want to interview somebody before he can work with me.

tocomment 13y ago
If only there were some way an employee could learn about btree's after taking a job...
- hvs 13y ago
  I don't want my employees to have to learn everything just-in-time. By that logic, the people you hire wouldn't need to know anything. In addition, they don't know what they don't know, so they may not even know that they need a btree index.
  - Tichy 13y ago
    Except that in my experience, software development is mostly about learning things just-in-time. Most projects pose new challenges, or you want to use new technologies, and so on. Imagine you hired some Cobol developers some decades ago, and therefore you would still be stuck using Cobol on your projects.
    - MartinCron 13y ago
      No, you would just fire all of the Cobol developers to bring in the experienced Pascal developers. How does one become an experienced Pascal developer? That's somebody else's problem.
  - marknutter 13y ago
    > I don't want my employees to have to learn everything just-in-time What about just some things. And in most cases, it's not learning for the first time but brushing up on the topic. To expect people to have encyclopedic knowledge of every edge-case problem your company deals with on a day-to-day basis is ridiculous.
    - dmatlack 13y ago
      As OP said, you would not be able to google the specific B-Tree question because if you don't know about B-Trees you wouldn't know that you need to google it. There's a difference between things you know you don't know (and therefore can google), and things you don't know you don't know (and therefore will not google).
      - marknutter 13y ago
        "I can see you're a bright individual and you have a great track record for writing and shipping good software, which is clear from your github account and your previous employers' endorsements. I have no doubt you'll be able to come up to speed on <insert obscure discipline> which is something we use a lot around here. We're looking for people who can learn quickly. Welcome aboard!"
  - toomuchtodo 13y ago
    I hire people based on their ability to learn, not what they know. If you're asking interview questions that can be googled in 20-30 seconds, you're wasting your time and theirs.
    - hvs 13y ago
      You have a pretty low opinion of our field if you think everything that you need to know about our field can be googled in 20-30 seconds. I'm not arguing about minutia questions, but if you can't be bothered to understand how and why to optimize a database or the difference between TCP and UDP (really?) and that's what the job requires, then I don't want to hire you.
      - toomuchtodo 13y ago
        My argument is don't play puzzles, don't ask stupid questions about "What does this command do with these flags?". An interview should be the same as a discussion about concepts you'd have with a colleague. Does the person know the concepts? That's all that matters.
    - bqe 13y ago
      Basic computer science knowledge (and yes, B-Trees qualifies) cannot be learned in 20 seconds. Most of this knowledge is actually a prerequisite to being able to search Google properly.
      - bobbbinsIII 13y ago
        how often does a normal software developer find himself in a situation where he has to know about B-Trees in depth?
        dmatlack 13y ago
        When he works for the company that this whole conversation is stemming from.
        bqe 13y ago
  - kevingibbon 13y ago
    This is a popular opinion which still makes hiring an art. The best people I have ever worked with are the people who are fast to learn, have amazing problem solving skills and are socially intelligent. That's it. No knowledge of btree required.
  - nawitus 13y ago
    >I don't want my employees to have to learn everything just-in-time. You can require knowledge without using dealbreakers like "you must know b-trees". A better alternative would be to say "you need to know 30% of the following group of things: b-trees, tcp/ip vs udp, ..." and so on.
    - bcoates 13y ago
      This is a lot like what I try to do in interviews, because I'm mostly just trying to filter out liars. I pick projects out of the candidate's resume and ask them about things they had to have learned to do the job they did.
  - geebee 13y ago
    What if they could explain what a b-tree is, and why they are useful, but that they'd have trouble implementing one on the spot. If they told you the name of a good book they know that has an explanation of b-trees. That they read the chapter a while ago, which is why they can generally explain what a b-tree is, and that that's where they'd go if b-trees came up and they needed to write/implement one? I don't mean to imply that this wouldn't be acceptable to you. I do "know" that I've been screened out after giving an answer like this (to the extent that I can really know the reason, legally they aren't allowed to say).
- arjie 13y ago
  The truth of the matter is that, for most of us, when faced with a problem we work with what we know. If you ensure breadth of knowledge, you can get better at each aspect, but if you only know a few fundamental ideas, that means that you have to be capable of looking at a problem and rediscovering the right data structure to handle it with. Essentially, you have to be as smart as the guys who came up with it in the first place and more. Better to know the data structures and how they work. Recognition is easier than rediscovery.
- falcolas 13y ago
  On the job training? Heresy! Shun the unbeliever, shun! In my own current position, I would not have gotten the job if they had interviewed me then like they interview new hires now. Don't know how to find and recover active but deleted files? Goodbye. Don't know how to follow strace around a distributed environment? See ya. No idea how the elevator works? Why are you even applying? I know how to do all of those things now, because I asked questions of my colleagues and the internet. I'm now the lead developer, not because I knew everything coming in, but because I am able to learn.
joyeuse6701 13y ago
I suppose if you're a network engineer http/udp/tcp is necessary to know maybe off hand but not really, http isn't even in the same network layer so I'd find it strange to even ask about the 'difference'. UDP and TCP differences are more or less a well known question but even then I've had some ask the question expecting the most basic of differences and others with the minutiae. btree index is also something that can be learned conceptually in about 10 minutes. It is far more important for me to see that someone can explain a project that they've worked on in the past with enough details to demonstrate sufficient technical knowledge than a litmus test based on somewhat arbitrary facts. 'don't know what lsof is? Not hired, I don't want someone who can't use shell'
- jlgreco 13y ago
  "http isn't even in the same network layer so I'd find it strange to even ask about the 'difference'" Why? You just answered it well enough. There are people who could not say what you just said; you don't want to waste your time on them.
- com2kid 13y ago
  Actually UDP and TCP are the prototypical examples of a reliable versus an unreliable protocol. Being familiar with protocol design is important no matter what type of programming one is doing, the ideas of ACKs, NACKs, and flow control pop up all over the place!
mscottmcbee 13y ago
I never understood the fascination with asking an applicant about minutia of data structures and algorithms. Isn't that the domain of reference material? I gain much more insight into a person by asking them to describe a large system they've designed, what choices they made, the effects those choices had, ect. How did their initial assumptions hold up through the course of the project? How did they adapt to changing requirements? These are the things you can't find the answer to in 30 seconds on stack overflow.
- taopao 13y ago
  Put yourselves in the shoes of an employer. There are a hundred candidates applying to your position. Would the answer of "just trust me" convince you to hire one person above the 99 other applicants? If only one of those 100 applicants showed they had the skills you wanted, right out of the box, wouldn't you feel better about hiring him? I think the attitude of "they should hire me, since I can learn anything" is self-centered. There are a lot more people that can't learn. Without testing methods available there is no way to distinguish the self-starters from the frauds.
  - bcoates 13y ago
    The problem is that most companies make terrible decisions about which skills they want right out of the box. They can't get people that are 100% on everything they actually need (as such people are unhireable for the job/pay they're offering), so they settle for people who know a lot about B+ trees (or more likely, how to reverse a linked list and do a bad version of quicksort on a whiteboard) because that's what the folks who have been studying their "how to get hired at a tech company" webpage know.
- PaulHoule 13y ago
  The answers of "look it up in a hashtable" and "look it up in the literature" will get you through a lot of interviews
- mlashcorp 13y ago
  I get your point, but knowing the differences between http, udp and tcp isn't minutia ... it's cornerstone knowledge for anyone working with distributed systems.
gtrubetskoy 13y ago
I don't know what kind of work you're in, but "knowing how a btree index works" (i mean how it really works, not just knowing the word "b-tree", if that's what you meant, nm) ranks pretty high in my book, it'd be outright bizarre if that same person didn't know the difference between udp and tcp?
jnbiche 13y ago
Can you not understand that there might be people who can complete your task easily, yet who have extreme anxiety about interviews? I actually understand this issue -- I've been trying to switch careers into programming for the past year. I've know several languages well (Python, JavaScript, some C), can use git, and have a few decently impressive projects on my Github profile. I also contribute to a pretty well-known open source project. As a result, it's not hard for me to get an interview. Nonetheless, I've discovered that despite being very good at interviewing in my prior (well, still current) career, I completely freeze when I interview for programming jobs. Programming interviews seem incredibly confrontational compared to my current profession. Interviewers seem to be out to trick you at something, or else to prove how much smarter they are than you. So I predictably freeze in these types of situations, to the point where I blank on things that I can usually do, even under pressure. It's been a big shock for me, since I did very well in school and went over a decade without "failing" an interview (i.e., taking an interview and not getting an offer) before attempting to transition into programming. But I love programming languages and software development, so I do contracts from time to time, which always go well. Unfortunately, I've not yet done a contract that was actually for a company that was actively hiring employees (most were for small businesses with no full-time developers). But this post has given me some hope. If there are companies willing to let a candidate work on short-term contracts to prove their worth, that means there's hope for me yet to be able to move into software development full-time.
- VladRussian2 13y ago
  >Programming interviews seem incredibly confrontational compared to my current profession. Interviewers seem to be out to trick you at something, or else to prove how much smarter they are than you. well, welcome to software engineering. The interviews are for the reason, they let you peek into your future job. If you can't manage that environment for 4 hours of the interviews, how you're expecting to manage it for many years if/when you get into software engineering? I'm not trying to be mean, i'm just warning that something like having a fresh out-of-college arrogant Millenial reviewing your code means - well suffice it to say that at my previous job it drove 6 out of 8 person team in 1 year, all from mid to senior engineers, me being 7th, to either change the team (3) or leave the company (4). The guy is a pest, smart, driven, high GPA from top University...
zura 13y ago
Believe me, your DBA or the person who writes queries doesn't need to know how exactly B-tree index works. Or even "B-tree" term. Just being aware about indexes and knowing when and where to add it would be sufficient.
- ibejoeb 13y ago
  I agree in principle that not everyone needs his entire algorithms curriculum resident in his head all the time. However, a DBA should understand the characteristics of the type of index he is implementing. B-tree isn't the only game in town.

by TeeWEE 13y ago

tocomment 13y ago

If only there were some way an employee could learn about btree's after taking a job...

hvs 13y ago
I don't want my employees to have to learn everything just-in-time. By that logic, the people you hire wouldn't need to know anything. In addition, they don't know what they don't know, so they may not even know that they need a btree index.
- Tichy 13y ago
  Except that in my experience, software development is mostly about learning things just-in-time. Most projects pose new challenges, or you want to use new technologies, and so on. Imagine you hired some Cobol developers some decades ago, and therefore you would still be stuck using Cobol on your projects.
  - MartinCron 13y ago
    No, you would just fire all of the Cobol developers to bring in the experienced Pascal developers. How does one become an experienced Pascal developer? That's somebody else's problem.
- marknutter 13y ago
  > I don't want my employees to have to learn everything just-in-time What about just some things. And in most cases, it's not learning for the first time but brushing up on the topic. To expect people to have encyclopedic knowledge of every edge-case problem your company deals with on a day-to-day basis is ridiculous.
  - dmatlack 13y ago
    As OP said, you would not be able to google the specific B-Tree question because if you don't know about B-Trees you wouldn't know that you need to google it. There's a difference between things you know you don't know (and therefore can google), and things you don't know you don't know (and therefore will not google).
    - marknutter 13y ago
      "I can see you're a bright individual and you have a great track record for writing and shipping good software, which is clear from your github account and your previous employers' endorsements. I have no doubt you'll be able to come up to speed on <insert obscure discipline> which is something we use a lot around here. We're looking for people who can learn quickly. Welcome aboard!"
- toomuchtodo 13y ago
  I hire people based on their ability to learn, not what they know. If you're asking interview questions that can be googled in 20-30 seconds, you're wasting your time and theirs.
  - hvs 13y ago
    You have a pretty low opinion of our field if you think everything that you need to know about our field can be googled in 20-30 seconds. I'm not arguing about minutia questions, but if you can't be bothered to understand how and why to optimize a database or the difference between TCP and UDP (really?) and that's what the job requires, then I don't want to hire you.
    - toomuchtodo 13y ago
      My argument is don't play puzzles, don't ask stupid questions about "What does this command do with these flags?". An interview should be the same as a discussion about concepts you'd have with a colleague. Does the person know the concepts? That's all that matters.
  - bqe 13y ago
    Basic computer science knowledge (and yes, B-Trees qualifies) cannot be learned in 20 seconds. Most of this knowledge is actually a prerequisite to being able to search Google properly.
    - bobbbinsIII 13y ago
      how often does a normal software developer find himself in a situation where he has to know about B-Trees in depth?
      - dmatlack 13y ago
        When he works for the company that this whole conversation is stemming from.
      - bqe 13y ago
- kevingibbon 13y ago
  This is a popular opinion which still makes hiring an art. The best people I have ever worked with are the people who are fast to learn, have amazing problem solving skills and are socially intelligent. That's it. No knowledge of btree required.
- nawitus 13y ago
  >I don't want my employees to have to learn everything just-in-time. You can require knowledge without using dealbreakers like "you must know b-trees". A better alternative would be to say "you need to know 30% of the following group of things: b-trees, tcp/ip vs udp, ..." and so on.
  - bcoates 13y ago
    This is a lot like what I try to do in interviews, because I'm mostly just trying to filter out liars. I pick projects out of the candidate's resume and ask them about things they had to have learned to do the job they did.
- geebee 13y ago
  What if they could explain what a b-tree is, and why they are useful, but that they'd have trouble implementing one on the spot. If they told you the name of a good book they know that has an explanation of b-trees. That they read the chapter a while ago, which is why they can generally explain what a b-tree is, and that that's where they'd go if b-trees came up and they needed to write/implement one? I don't mean to imply that this wouldn't be acceptable to you. I do "know" that I've been screened out after giving an answer like this (to the extent that I can really know the reason, legally they aren't allowed to say).
arjie 13y ago
The truth of the matter is that, for most of us, when faced with a problem we work with what we know. If you ensure breadth of knowledge, you can get better at each aspect, but if you only know a few fundamental ideas, that means that you have to be capable of looking at a problem and rediscovering the right data structure to handle it with. Essentially, you have to be as smart as the guys who came up with it in the first place and more. Better to know the data structures and how they work. Recognition is easier than rediscovery.
falcolas 13y ago
On the job training? Heresy! Shun the unbeliever, shun! In my own current position, I would not have gotten the job if they had interviewed me then like they interview new hires now. Don't know how to find and recover active but deleted files? Goodbye. Don't know how to follow strace around a distributed environment? See ya. No idea how the elevator works? Why are you even applying? I know how to do all of those things now, because I asked questions of my colleagues and the internet. I'm now the lead developer, not because I knew everything coming in, but because I am able to learn.

joyeuse6701 13y ago

I suppose if you're a network engineer http/udp/tcp is necessary to know maybe off hand but not really, http isn't even in the same network layer so I'd find it strange to even ask about the 'difference'. UDP and TCP differences are more or less a well known question but even then I've had some ask the question expecting the most basic of differences and others with the minutiae. btree index is also something that can be learned conceptually in about 10 minutes. It is far more important for me to see that someone can explain a project that they've worked on in the past with enough details to demonstrate sufficient technical knowledge than a litmus test based on somewhat arbitrary facts. 'don't know what lsof is? Not hired, I don't want someone who can't use shell'

jlgreco 13y ago
"http isn't even in the same network layer so I'd find it strange to even ask about the 'difference'" Why? You just answered it well enough. There are people who could not say what you just said; you don't want to waste your time on them.
com2kid 13y ago
Actually UDP and TCP are the prototypical examples of a reliable versus an unreliable protocol. Being familiar with protocol design is important no matter what type of programming one is doing, the ideas of ACKs, NACKs, and flow control pop up all over the place!

mscottmcbee 13y ago

I never understood the fascination with asking an applicant about minutia of data structures and algorithms. Isn't that the domain of reference material? I gain much more insight into a person by asking them to describe a large system they've designed, what choices they made, the effects those choices had, ect. How did their initial assumptions hold up through the course of the project? How did they adapt to changing requirements? These are the things you can't find the answer to in 30 seconds on stack overflow.

taopao 13y ago
Put yourselves in the shoes of an employer. There are a hundred candidates applying to your position. Would the answer of "just trust me" convince you to hire one person above the 99 other applicants? If only one of those 100 applicants showed they had the skills you wanted, right out of the box, wouldn't you feel better about hiring him? I think the attitude of "they should hire me, since I can learn anything" is self-centered. There are a lot more people that can't learn. Without testing methods available there is no way to distinguish the self-starters from the frauds.
- bcoates 13y ago
  The problem is that most companies make terrible decisions about which skills they want right out of the box. They can't get people that are 100% on everything they actually need (as such people are unhireable for the job/pay they're offering), so they settle for people who know a lot about B+ trees (or more likely, how to reverse a linked list and do a bad version of quicksort on a whiteboard) because that's what the folks who have been studying their "how to get hired at a tech company" webpage know.
PaulHoule 13y ago
The answers of "look it up in a hashtable" and "look it up in the literature" will get you through a lot of interviews
mlashcorp 13y ago
I get your point, but knowing the differences between http, udp and tcp isn't minutia ... it's cornerstone knowledge for anyone working with distributed systems.

gtrubetskoy 13y ago

I don't know what kind of work you're in, but "knowing how a btree index works" (i mean how it really works, not just knowing the word "b-tree", if that's what you meant, nm) ranks pretty high in my book, it'd be outright bizarre if that same person didn't know the difference between udp and tcp?

jnbiche 13y ago

Can you not understand that there might be people who can complete your task easily, yet who have extreme anxiety about interviews? I actually understand this issue -- I've been trying to switch careers into programming for the past year. I've know several languages well (Python, JavaScript, some C), can use git, and have a few decently impressive projects on my Github profile. I also contribute to a pretty well-known open source project. As a result, it's not hard for me to get an interview. Nonetheless, I've discovered that despite being very good at interviewing in my prior (well, still current) career, I completely freeze when I interview for programming jobs. Programming interviews seem incredibly confrontational compared to my current profession. Interviewers seem to be out to trick you at something, or else to prove how much smarter they are than you. So I predictably freeze in these types of situations, to the point where I blank on things that I can usually do, even under pressure. It's been a big shock for me, since I did very well in school and went over a decade without "failing" an interview (i.e., taking an interview and not getting an offer) before attempting to transition into programming. But I love programming languages and software development, so I do contracts from time to time, which always go well. Unfortunately, I've not yet done a contract that was actually for a company that was actively hiring employees (most were for small businesses with no full-time developers). But this post has given me some hope. If there are companies willing to let a candidate work on short-term contracts to prove their worth, that means there's hope for me yet to be able to move into software development full-time.

VladRussian2 13y ago
>Programming interviews seem incredibly confrontational compared to my current profession. Interviewers seem to be out to trick you at something, or else to prove how much smarter they are than you. well, welcome to software engineering. The interviews are for the reason, they let you peek into your future job. If you can't manage that environment for 4 hours of the interviews, how you're expecting to manage it for many years if/when you get into software engineering? I'm not trying to be mean, i'm just warning that something like having a fresh out-of-college arrogant Millenial reviewing your code means - well suffice it to say that at my previous job it drove 6 out of 8 person team in 1 year, all from mid to senior engineers, me being 7th, to either change the team (3) or leave the company (4). The guy is a pest, smart, driven, high GPA from top University...

zura 13y ago

Believe me, your DBA or the person who writes queries doesn't need to know how exactly B-tree index works. Or even "B-tree" term. Just being aware about indexes and knowing when and where to add it would be sufficient.

ibejoeb 13y ago
I agree in principle that not everyone needs his entire algorithms curriculum resident in his head all the time. However, a DBA should understand the characteristics of the type of index he is implementing. B-tree isn't the only game in town.