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  1. MariaDB MaxScale
  2. MXS-1382

Use wsrep_sync_wait to detect replication lag in Galera clusters

Details

    • New Feature
    • Status: Closed (View Workflow)
    • Trivial
    • Resolution: Won't Do
    • 2.5
    • N/A
    • galeramon

    Description

      The Galera monitor can detect the lag between certification and application of events in a Galera cluster by writing an event on the write-master node and doing "dirty reads" on the nodes labeled as slaves. This gives similar functionality for Galera clusters that is already in place for Master-Slave clusters in mysqlmon.

      Another option is to use wsrep_local_recv_queue as a measurement of lag in a Galera cluster.

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          markus makela markus makela created issue -
          markus makela markus makela made changes -
          Field Original Value New Value
          Description The Galera monitor can detect the lag between certification and application of events in a Galera cluster by writing an event on the write-master node and doing "dirty reads" on the nodes labeled as slaves. This gives similar functionality for Galera clusters that is already in place for Master-Slave clusters in mysqlmon. The Galera monitor can detect the lag between certification and application of events in a Galera cluster by writing an event on the write-master node and doing "dirty reads" on the nodes labeled as slaves. This gives similar functionality for Galera clusters that is already in place for Master-Slave clusters in mysqlmon.

          Another option is to use wsrep_local_recv_queue as a measurement of lag in a Galera cluster.
          markus makela markus makela made changes -
          Priority Major [ 3 ] Trivial [ 5 ]
          toddstoffel Todd Stoffel (Inactive) made changes -
          Assignee Todd Stoffel [ toddstoffel ]
          toddstoffel Todd Stoffel (Inactive) made changes -
          Affects Version/s N.M [ 22648 ]
          toddstoffel Todd Stoffel (Inactive) made changes -
          Fix Version/s N.M [ 22648 ]
          toddstoffel Todd Stoffel (Inactive) made changes -
          Fix Version/s 2.5 [ 23255 ]
          Fix Version/s N.M [ 22648 ]
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          Epic Link MXS-2531 [ 76495 ]
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          toddstoffel Todd Stoffel (Inactive) made changes -
          Fix Version/s 2.6 [ 23714 ]
          Fix Version/s 2.5 [ 23255 ]
          johan.wikman Johan Wikman made changes -
          Rank Ranked lower
          toddstoffel Todd Stoffel (Inactive) made changes -
          Team MaxScale Board Team
          GeoffMontee Geoff Montee (Inactive) added a comment -

          Another option is to use wsrep_local_recv_queue as a measurement of lag in a Galera cluster.

          ProxySQL already supports something like this:

          max_transactions_behind - determines the maximum number of writesets behind the cluster that ProxySQL should allow before shunning the node to prevent stale reads (this is determined by querying the wsrep_local_recv_queue Galera variable).

          https://github.com/sysown/proxysql/wiki/Main-(runtime)#mysql_galera_hostgroups

          GeoffMontee Geoff Montee (Inactive) added a comment - Another option is to use wsrep_local_recv_queue as a measurement of lag in a Galera cluster. ProxySQL already supports something like this: max_transactions_behind - determines the maximum number of writesets behind the cluster that ProxySQL should allow before shunning the node to prevent stale reads (this is determined by querying the wsrep_local_recv_queue Galera variable). https://github.com/sysown/proxysql/wiki/Main-(runtime)#mysql_galera_hostgroups
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          toddstoffel Todd Stoffel (Inactive) made changes -
          Labels Galera
          toddstoffel Todd Stoffel (Inactive) made changes -
          Affects Version/s 2.5 [ 23255 ]
          Affects Version/s Icebox [ 22648 ]
          toddstoffel Todd Stoffel (Inactive) made changes -
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          toddstoffel Todd Stoffel (Inactive) made changes -
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          toddstoffel Todd Stoffel (Inactive) made changes -
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          toddstoffel Todd Stoffel (Inactive) made changes -
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          serg Sergei Golubchik made changes -
          Workflow MariaDB v3 [ 82343 ] MariaDB v4 [ 136531 ]
          johan.wikman Johan Wikman made changes -
          Fix Version/s N/A [ 22001 ]
          Fix Version/s 6 [ 23714 ]
          Resolution Won't Do [ 10201 ]
          Status Open [ 1 ] Closed [ 6 ]
          mariadb-jira-automation Jira Automation (IT) made changes -
          Zendesk Related Tickets 173198

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            toddstoffel Todd Stoffel (Inactive)
            markus makela markus makela
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