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  1. MariaDB Server
  2. MDEV-7292

Table_open_cache scalability issues

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Details

    • Bug
    • Status: Closed (View Workflow)
    • Major
    • Resolution: Incomplete
    • 10.0.15
    • 10.0.16
    • OTHER
    • None
    • Debian wheezy x86_64

    Description

      Hello,

      in spite of recent effors, table_open_cache still seems to be hit by negative scalability. I ran the following benchmark tests:

      • SET GLOBAL table_open_cache = 64
      • Create 10,000 MyISAM Tables with a single integer
      • Access all tables in a loop
      • SET GLOBAL table_open_cache = 4000
      • Access all tables in a loop

      Results are the following:
      Table creation: 4s (sync_frm=0)
      SELECT, Table_open_cache=64: 1.696519199s
      SELECT, Table_open_cache=4000: 5.946816624s

      The results are quite consistent and performance seems to decrease linearly.

      My biggest concern is that MariaDB 5.5.40 is 2x faster with this test:

      Selecting from tables with default cache (64)
      Time: 1.536537015s
      Selecting from tables with extended cache (4000)
      Time: 2.798534456s

      The only good news is that MySQL 5.6 seems to do worse with this test, with 6s and 9s respectively.

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              svoj Sergey Vojtovich
              tanj Guillaume Lefranc
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              Dates

                Created:
                Updated:
                Resolved:

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