Interviews: Covering index

  • Steve Jones - SSC Editor

    SSC Guru

    Points: 716619

    Comments posted to this topic are about the item Interviews: Covering index

  • Eric M Russell

    SSC Guru

    Points: 125032

    I like questions related to covering indexes, and I always have that card in the interview deck, because answering this question involves practical knowledge, especially if the interviewer asks a followup question like: "So, how do you know that a query is actually covered by an index?". Many candidates applying for an application development job may consider intermediate level questions about things like covering indexes to be "tricky". However, if the candidate would actually be coding SQL or modeling tables and indexes as part of their job, then it's not a trick question.

    "Do not seek to follow in the footsteps of the wise. Instead, seek what they sought." - Matsuo Basho

  • Frank W Fulton Jr

    SSCommitted

    Points: 1599

    Thanks Steve, Once again you have proved why I love your newsletter, and site. I am not a Professional DBA.
    But I need to understand and be able to use SQL as a Developer, and the more I understand what a DBA has to deal with, the better I am as a developer.
    Thanks Again

  • Steve Jones - SSC Editor

    SSC Guru

    Points: 716619

    Frank W Fulton Jr - Wednesday, March 21, 2018 4:33 PM

    Thanks Steve, Once again you have proved why I love your newsletter, and site. I am not a Professional DBA.
    But I need to understand and be able to use SQL as a Developer, and the more I understand what a DBA has to deal with, the better I am as a developer.
    Thanks Again

    You are quite welcome, and glad I can help.

  • Manie Verster

    SSCertifiable

    Points: 7020

    No, sir, I do not know what a covering index is. That will be my answer. I have found being honest in interviews is the best practice. I landed my current job on being honest. I will now definitely read up on covering indexes because this is the first time I have heard about it but then. I am a developer and that might be the reason. You are correct in saying that developers that when we develop a new project or add to an existing project that indexing is not a very high priority but as we go on and see that the screens that we work on is slow then we will start to do performance tuning. However if from the get go we see tuning is necessary we will do it.
    Thank you for showing me something new I need to learn.

    :-PManie Verster
    Developer
    Johannesburg
    South Africa

    I can do all things through Christ who strengthens me. - Holy Bible
    I am a man of fixed and unbending principles, the first of which is to be flexible at all times. - Everett Mckinley Dirkson (Well, I am trying. - Manie Verster)

  • Manie Verster

    SSCertifiable

    Points: 7020

    Eric M Russell - Wednesday, March 21, 2018 8:06 AM

    I like questions related to covering indexes, and I always have that card in the interview deck, because answering this question involves practical knowledge, especially if the interviewer asks a followup question like: "So, how do you know that a query is actually covered by an index?". Many candidates applying for an application development job may consider intermediate level questions about things like covering indexes to be "tricky". However, if the candidate would actually be coding SQL or modeling tables and indexes as part of their job, then it's not a trick question.

    I fully agree with Eric.

    :-PManie Verster
    Developer
    Johannesburg
    South Africa

    I can do all things through Christ who strengthens me. - Holy Bible
    I am a man of fixed and unbending principles, the first of which is to be flexible at all times. - Everett Mckinley Dirkson (Well, I am trying. - Manie Verster)

  • Jeff Moden

    SSC Guru

    Points: 995144

    Frank W Fulton Jr - Wednesday, March 21, 2018 4:33 PM

    Thanks Steve, Once again you have proved why I love your newsletter, and site. I am not a Professional DBA.
    But I need to understand and be able to use SQL as a Developer, and the more I understand what a DBA has to deal with, the better I am as a developer.
    Thanks Again

    What a refreshing change your comments are.  That's the fundamental principle behind the very effective culture of "DevOps"  That's also why, as a DBA, I sit with the Developers (and I used to be a Developer) because knowing what they have to go through makes me a better DBA.

    --Jeff Moden


    RBAR is pronounced "ree-bar" and is a "Modenism" for Row-By-Agonizing-Row.
    First step towards the paradigm shift of writing Set Based code:
    ________Stop thinking about what you want to do to a row... think, instead, of what you want to do to a column.
    "If you think its expensive to hire a professional to do the job, wait until you hire an amateur."--Red Adair
    "Change is inevitable... change for the better is not."
    When you put the right degree of spin on it, the number 3|8 is also a glyph that describes the nature of a DBAs job. 😉

    Helpful Links:
    How to post code problems
    Create a Tally Function (fnTally)

  • Manie Verster

    SSCertifiable

    Points: 7020

    Jeff Moden - Thursday, March 22, 2018 4:03 PM

    Frank W Fulton Jr - Wednesday, March 21, 2018 4:33 PM

    Thanks Steve, Once again you have proved why I love your newsletter, and site. I am not a Professional DBA.
    But I need to understand and be able to use SQL as a Developer, and the more I understand what a DBA has to deal with, the better I am as a developer.
    Thanks Again

    What a refreshing change your comments are.  That's the fundamental principle behind the very effective culture of "DevOps"  That's also why, as a DBA, I sit with the Developers (and I used to be a Developer) because knowing what they have to go through makes me a better DBA.

    Frank and Jeff,
    Thank you for the comments and as Jeff said it is refreshing to read comments like this where dbas and developers are not trying to point out each other's flaws but try to understand each other's positions.
    Great job guys!!!

    :-PManie Verster
    Developer
    Johannesburg
    South Africa

    I can do all things through Christ who strengthens me. - Holy Bible
    I am a man of fixed and unbending principles, the first of which is to be flexible at all times. - Everett Mckinley Dirkson (Well, I am trying. - Manie Verster)

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