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  1. MariaDB Server
  2. MDEV-30456

Galera / MariaDB issue with ALTER TABLE statement still propagating to other cluster members in TOI while it failed on origin server

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Details

    • Bug
    • Status: In Review (View Workflow)
    • Critical
    • Resolution: Unresolved
    • 10.3, 10.5
    • 10.5
    • Galera
    • None

    Description

      Hi, I'm new here so I'm not really sure what are the minimal requirements for a bug report so I'll just work from my own experience for now:

      We had an incident this morning whereby an ALTER TABLE statement was executed on a server in a cluster of 3 servers. This became an outage for us because the statement resulted in a COPY algorithm being used on a large table (in member 2 and 3 of the cluster) which (at least in my opinion) should have been prevented by the statements that were done on member 1 of the cluster:

      SET SESSION alter_algorithm="INSTANT";
      alter table some_large_table_containing_blobs
          modify type enum ('existing_option1','existing_option3','existing_option2') null;
      

      Note that the enum order changed by accident which caused the COPY algorithm to be needed which made it fail on member 1 which in turn didn't stop it from propagating the query to the other cluster members somehow (this seems like unwanted behavior to me). I've checked this by using SHOW PROCESSLIST; on all machines and found that it was only running on both members 2 and 3 while it clearly showed me the following error on member 1 to which I was connected while running the queries: ALGORITHM=INSTANT is not supported. Reason: Cannot change column type. Try ALGORITHM=COPY

      Some version information:

      [root@db1 ~]# yum list installed | grep galera
      galera.x86_64                      25.3.37-1.el7.centos            @mariadb-main
      [root@db1 ~]# yum list installed | grep MariaDB
      MariaDB-backup.x86_64              10.3.36-1.el7.centos            @mariadb-main
      MariaDB-client.x86_64              10.3.36-1.el7.centos            @mariadb-main
      MariaDB-common.x86_64              10.3.36-1.el7.centos            @mariadb-main
      MariaDB-compat.x86_64              10.3.36-1.el7.centos            @mariadb-main
      MariaDB-server.x86_64              10.3.36-1.el7.centos            @mariadb-main
      

      I was wondering if this might be a known issue somehow? Or if this is really a bug? And if so is it a bug in Galera or in MariaDB?

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              sysprg Julius Goryavsky
              bravoman Tom
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                Updated:

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