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  1. MariaDB Server
  2. MDEV-9165

Debian postinstall chown or the datadir takes too long on servers with many files on the datadir

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    Details

    • Type: Bug
    • Status: Closed (View Workflow)
    • Priority: Minor
    • Resolution: Fixed
    • Affects Version/s: 5.5.46, 10.0.22, 10.1.8
    • Fix Version/s: 10.2.3
    • Component/s: Platform Debian
    • Labels:
      None
    • Environment:
      Debian

      Description

      I recently experienced a slow MariaDB upgrade/migration from MySQL 5.5 to MariaDB 5.5, after the server has been stopped it took maybe one or two minutes before starting the new one.

      A process doing a "chown mysql -R /var/lib/mysql" was runing for quite a long time.
      This particular server has about 350000 files on its datadir, while its far from being the best practice its not easy to change that (its a shared hosting server).

      Replacing the line on "mariadb-server-*.postinst" :

      chown -R mysql $mysql_datadir

      With something like (there is probably a better alternative) :

      find /var/lib/mysql/ ! -uid $(id -u mysql) -print0 |xargs -0 -r chown mysql

      It seems to be marginally slower (less than 1/100th of a second on my tests) on small directories but faster on directories with many files on it (about 20-40% faster on a directory with only 25k files on a software raid1 with 2* 7200k HDDs).

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            Assignee:
            otto Otto Kekäläinen
            Reporter:
            jb-boin Jean Weisbuch
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