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  1. MariaDB Server
  2. MDEV-699

LP:1007806 - index_merge/interesection is picked when it seems to be the best plan

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Details

    • Bug
    • Status: Open (View Workflow)
    • Trivial
    • Resolution: Unresolved
    • 5.3.12, 5.5.36, 10.0.10
    • 10.2(EOL)
    • None

    Description

      Look at the testcase for https://bugs.launchpad.net/maria/+bug/1006164. The DELETE statement (but not its SELECT analog for some reason) uses index_merge/intersect strategy. This choice looks a bit odd, because each of the merged scans selects only a few records.

      I'm not stating the choice is wrong, but this example is something we could look at when/if we're going to tune index_merge cost model.

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            psergei Sergei Petrunia
            psergei Sergei Petrunia
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              Updated:

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