Risks of NOLOCK, part 2

  • Thanks Hugo

    I know that double negation isn't considered acceptable in current standard English, but in

    this case you had to use it and this sentence is logically correct for me.

    However, I always was aware of putting nolock in every query is a bad habit and can return

    unexpected results. I don't use this hint, so my knowledge is not too big about it.

    Thank you again for the excellent explanation.



  • Thanks for a good question to continue the topic, Hugo. This type of thing not only challenges what I think I know, but also forced me to slow down and read the answers carefully.

  • Thanks for the question.

  • Another excellent question. Will there be a third in the series?


  • Hugo Kornelis (11/3/2015)[hrSteve, if you see this - any chance that you can get this fixed? I don't think it will cause people to miss the question, but it does annoy me. 🙂

    I don't know whether it's changed since then, but the third answer option now reads "Nolock CAN cause the query to not return committed rowsNolock CAN NOT cause the query to not return committed rows", so the second bit (which is the same as the fourth option) wants chopping off. I don't think it will confuse anyone who is thinking clearly as it's obviously an error and can't be intended to mean the same as the next option, so it must mean what the first part of it says.


  • michal.lisinski (11/4/2015)

    I know that double negation isn't considered acceptable in current standard English, but ...

    I guess that depends on what you mean by (a) "double negation" and (b) "current standard English". If the former means "multiple negation with negative concord" and "current standard English" means "standard formal British English of period from the accession of Queen Victoria to the current day" then I agree, but if "double negation" means "multiple negation with negative polarity" then I disagree because today's standard British English has exactly that (and that is what Hugo was using). If by current standard English you meant for example "accepted standard Britsh English of the 18th century" (I know you didn't, of course) you would be wrong with either meaning of of "double negation" since that was during the transition period between negative concord and negative polarity in formal British English and both were accptable. And in many places/social circles using the modern formal British standard will create misunderstanding - and in some of those places/circles negative concord is the current standard, so you would be wrong if you meant the English of such a place or circle.


  • TomThomson (11/6/2015)

    Another excellent question. Will there be a third in the series?

    Thanks! And no, this series is now done.

    I do have two other questions lined up, though; they will be about execution plans. And I try to come up with more ideas.

    Hugo Kornelis, SQL Server/Data Platform MVP (2006-2016)
    Visit my SQL Server blog: https://sqlserverfast.com/blog/
    SQL Server Execution Plan Reference: https://sqlserverfast.com/epr/

  • Great question Hugo, thanks.

    Need an answer? No, you need a question
    My blog at https://sqlkover.com.
    MCSE Business Intelligence - Microsoft Data Platform MVP

  • Thanks for the excellent questions, Hugo. I look forward to your next ones!

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