Details

    • Sub-Task
    • Status: Closed (View Workflow)
    • Critical
    • Resolution: Won't Do
    • None
    • 23.10.0
    • PrimProc
    • None
    • 2021-7, 2021-8, 2021-9, 2021-10, 2021-11, 2021-12

    Description

      The goal is to evaluate a proposal to correct the performance problem.

      The method:

      • create a test version of latin1_nopad_bin collation function which would use MURMUR.
      • measure the difference in performance (the expectation is 2x vs current 6x).
      • compare behavior of aggregate queries which use so updated collation against:
        a) original CS method - present in 1.2
        b) current - as in 5.5.2

      The last should be done using both flights (30 million rows) and Quinnstreet (1 billion rows).

      Once we have the facts, we will be making a decision on what to do.

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          drrtuy Roman added a comment -

          I am curious what exactly are we talking about: collation-aware comparators or hashers?
          If we are talking comparators MM3 is outside the scope. If we are talking hashers a different story. There are multiple SQL operators that uses hashing, e.g. JOIN, GROUP BY, DISTINCT. JFYI GB and JOIN are using MM3 to hash weights arrays that represents char/varchar/text preserving order relation. Here is where the hashing takes place. JOIN still uses MDB hashing internally. DISTINCT is using MDB hashing also but I am aware that it will be replaced with GB code.

          drrtuy Roman added a comment - I am curious what exactly are we talking about: collation-aware comparators or hashers? If we are talking comparators MM3 is outside the scope. If we are talking hashers a different story. There are multiple SQL operators that uses hashing, e.g. JOIN, GROUP BY, DISTINCT. JFYI GB and JOIN are using MM3 to hash weights arrays that represents char/varchar/text preserving order relation. Here is where the hashing takes place. JOIN still uses MDB hashing internally. DISTINCT is using MDB hashing also but I am aware that it will be replaced with GB code.

          People

            leonid.fedorov Leonid Fedorov
            gdorman Gregory Dorman (Inactive)
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