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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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          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

          People

            toddstoffel Todd Stoffel (Inactive)
            markus makela markus makela
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