05 - Buffer Pools (CMU Intro to Database Systems / Fall 2021)

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  • เผยแพร่เมื่อ 29 พ.ย. 2024

ความคิดเห็น • 7

  • @CppExpedition
    @CppExpedition 8 หลายเดือนก่อน +3

    Congratulations to those who reach this point.
    YOU HAVE REACHED 20% of the course.
    AND FROM THE PARETO MODEL, YOU HAVE NOW 80% of the most used stuff in practical life.
    Keep going on! your next goal is 40% of this course!

  • @qm3ster
    @qm3ster 2 ปีที่แล้ว

    44:20 isn't AVG(val) just SUM(val)/COUNT?
    Can't it just wait for the sum to finish and divide by the count, possibly cached from some other query?

    • @Aditya-ne4lk
      @Aditya-ne4lk 2 ปีที่แล้ว

      I don't think that's tenable. It would essentially mean blocking the second query until the first query is finished, it seems trivial because of the use case, but for a more complex query you would not want to make a second query wait.

    • @qm3ster
      @qm3ster 2 ปีที่แล้ว +1

      @@Aditya-ne4lk right. And with the LIMIT on the AVG it would *have* to be a SUM that started from page0.
      While instead a SUM that started elsewhere could be running, which at no point in its run would hold the correct value.
      However, if there *is* a SUM running from page0, and it scanned less than 100 rows so far, that would be insane work saving.

  • @codhjosa5264
    @codhjosa5264 2 ปีที่แล้ว +3

    Omg Andrew Crotty is so handsome I fell in love with him 😘😘😘😘😘😘

  • @qm3ster
    @qm3ster 2 ปีที่แล้ว

    I paused and googled why someone would say latch vs lock right before the slide switched T_T