Uploaded image for project: 'MariaDB Server'
  1. MariaDB Server
  2. MDEV-7292

Table_open_cache scalability issues

    XMLWordPrintable

    Details

    • Type: Bug
    • Status: Closed (View Workflow)
    • Priority: Major
    • Resolution: Incomplete
    • Affects Version/s: 10.0.15
    • Fix Version/s: 10.0.16
    • Component/s: OTHER
    • Labels:
      None
    • Environment:
      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.

        Attachments

          Issue Links

            Activity

              People

              Assignee:
              svoj Sergey Vojtovich
              Reporter:
              tanj Guillaume Lefranc
              Votes:
              2 Vote for this issue
              Watchers:
              6 Start watching this issue

                Dates

                Created:
                Updated:
                Resolved: