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  1. MariaDB ColumnStore
  2. MCOL-2217

Document why processes might be in the cold standby or hot standby state

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      Description

      In a multi-UM configuration, processes such as DDLProc and DMLProc can sometimes show up in the COLD_STANDBY or the HOT_STANDBY state.

      For example:

      > getSystemInfo
      getsysteminfo   Mon Mar  4 14:24:58 2019
       
      System cstore-3
       
      System and Module statuses
       
      Component     Status                       Last Status Change
      ------------  --------------------------   ------------------------
      System        ACTIVE                       Fri Mar  1 20:19:14 2019
       
      Module um1    ACTIVE                       Fri Mar  1 20:19:12 2019
      Module um2    ACTIVE                       Fri Mar  1 20:19:16 2019
      Module pm1    ACTIVE                       Fri Mar  1 20:15:31 2019
      Module pm2    ACTIVE                       Fri Mar  1 20:19:15 2019
       
      Active Parent OAM Performance Module is 'pm1'
      Primary Front-End MariaDB ColumnStore Module is 'um1'
      MariaDB ColumnStore Replication Feature is enabled
      MariaDB ColumnStore set for Distributed Install
       
       
      MariaDB ColumnStore Process statuses
       
      Process             Module    Status            Last Status Change        Process ID
      ------------------  ------    ---------------   ------------------------  ----------
      ProcessMonitor      um1       ACTIVE            Fri Mar  1 20:14:57 2019        3838
      ServerMonitor       um1       ACTIVE            Fri Mar  1 20:15:29 2019        6033
      DBRMWorkerNode      um1       ACTIVE            Fri Mar  1 20:18:24 2019       12918
      ExeMgr              um1       ACTIVE            Fri Mar  1 20:18:54 2019       13155
      DDLProc             um1       ACTIVE            Fri Mar  1 20:19:02 2019       13210
      DMLProc             um1       ACTIVE            Fri Mar  1 20:19:07 2019       13268
      mysqld              um1       ACTIVE            Fri Mar  1 20:19:12 2019       13761
       
      ProcessMonitor      um2       ACTIVE            Fri Mar  1 20:14:56 2019        3855
      ServerMonitor       um2       ACTIVE            Fri Mar  1 20:15:35 2019        5437
      DBRMWorkerNode      um2       ACTIVE            Fri Mar  1 20:18:29 2019       10065
      ExeMgr              um2       ACTIVE            Fri Mar  1 20:18:58 2019       10302
      DDLProc             um2       COLD_STANDBY      Fri Mar  1 20:19:04 2019
      DMLProc             um2       COLD_STANDBY      Fri Mar  1 20:19:06 2019
      mysqld              um2       ACTIVE            Fri Mar  1 20:19:16 2019       10840
       
      ProcessMonitor      pm1       ACTIVE            Fri Mar  1 20:14:39 2019        3835
      ProcessManager      pm1       ACTIVE            Fri Mar  1 20:14:45 2019       13482
      DBRMControllerNode  pm1       ACTIVE            Fri Mar  1 20:18:22 2019       18294
      ServerMonitor       pm1       ACTIVE            Fri Mar  1 20:15:28 2019       14632
      DBRMWorkerNode      pm1       ACTIVE            Fri Mar  1 20:18:33 2019       18406
      PrimProc            pm1       ACTIVE            Fri Mar  1 20:18:41 2019       18508
      WriteEngineServer   pm1       ACTIVE            Fri Mar  1 20:18:48 2019       18589
       
      ProcessMonitor      pm2       ACTIVE            Fri Mar  1 20:15:13 2019        3838
      ProcessManager      pm2       HOT_STANDBY       Fri Mar  1 20:15:14 2019        5424
      DBRMControllerNode  pm2       COLD_STANDBY      Fri Mar  1 20:19:15 2019
      ServerMonitor       pm2       ACTIVE            Fri Mar  1 20:15:39 2019        5579
      DBRMWorkerNode      pm2       ACTIVE            Fri Mar  1 20:18:37 2019        6065
      PrimProc            pm2       ACTIVE            Fri Mar  1 20:18:42 2019        6086
      WriteEngineServer   pm2       ACTIVE            Fri Mar  1 20:18:49 2019        6131
       
      Active Alarm Counts: Critical = 0, Major = 0, Minor = 0, Warning = 0, Info = 0
      

      It does not seem to be documented anywhere how processes may end up in this state. For example, it is not mentioned on the following pages:

      https://mariadb.com/kb/en/library/columnstore-multiple-user-module-guide/

      https://mariadb.com/kb/en/library/managing-columnstore-module-configurations/

      And the COLD_STANDBY state doesn't even seem to be mentioned here:

      https://mariadb.com/kb/en/library/columnstore-system-operations/#viewing-process-status

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            Reporter:
            GeoffMontee Geoff Montee
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              Updated:

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