[#MXS-1382] Use wsrep_sync_wait to detect replication lag in Galera clusters

[MXS-1382] Use wsrep_sync_wait to detect replication lag in Galera clusters Created: 2017-08-31 Updated: 2022-09-08 Resolved: 2022-09-08
Status:	Closed
Project:	MariaDB MaxScale
Component/s:	galeramon
Affects Version/s:	2.5
Fix Version/s:	N/A

Type:

New Feature

Priority:

Trivial

Reporter:

markus makela

Assignee:

Todd Stoffel (Inactive)

Resolution:

Won't Do

Votes:

Labels:

Galera

Epic Link:

Monitor Improvements

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.

Comments

Comment by Geoff Montee (Inactive) [ 2020-01-16 ]

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

Generated at Thu Feb 08 04:06:19 UTC 2024 using Jira 8.20.16#820016-sha1:9d11dbea5f4be3d4cc21f03a88dd11d8c8687422.

[MXS-1382] Use wsrep_sync_wait to detect replication lag in Galera clusters Created: 2017-08-31 Updated: 2022-09-08 Resolved: 2022-09-08