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  1. Percona XtraBackup
  2. PXB-704

LP #1372679: innobackupex --slave-info doesn't handle slave_parallel_workers>0

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    • Type: Bug
    • Status: Done
    • Priority: High
    • Resolution: Fixed
    • Affects Version/s: None
    • Fix Version/s: None
    • Component/s: None
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      Description

      **Reported in Launchpad by Kolbe last update 15-12-2017 09:24:51

      From http://dev.mysql.com/doc/refman/5.6/en/show-slave-status.html:

      "When using a multi-threaded slave (by setting slave_parallel_workers to a nonzero value in MySQL 5.6.3 and later), the value in [the Exec_Master_Log_Pos] column actually represents a low-water mark, before which no uncommitted transactions remain. Because the current implementation allows execution of transactions on different databases in a different order on the slave than on the master, this is not necessarily the position of the most recently executed transaction."

      So, it is not safe to rely on Exec_Master_Log_Pos for "latest executed position in master binary log" if parallel replication is used, i.e. slave_parallel_workers>0.

      innobackupex should refuse to allow the use of the --slave-info option if slave_parallel_workers>0.

      A new option to innobackupex could be offered that would execute a sequence such as this:

      SET @old_slave_parallel_workers:=@@slave_parallel_workers;
      SET GLOBAL slave_parallel_workers=0;
      STOP SLAVE;
      START SLAVE;
      ...execute backup logic...
      SET GLOBAL slave_parallel_workers=@old_slave_parallel_workers;
      STOP SLAVE;
      START SLAVE;

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                • Assignee:
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                  Reporter:
                  lpjirasync lpjirasync (Inactive)
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