Percona XtraDB Cluster - HA scalable solution for MySQL

wsrep variable to reject queries

Reported by Raghavendra D Prabhu on 2013-05-14
12
This bug affects 2 people
Affects Status Importance Assigned to Milestone
Percona XtraDB Cluster
Status tracked in Trunk
5.6
Undecided
Unassigned
Trunk
Undecided
Raghavendra D Prabhu

Bug Description

Similar to wsrep_sst_donor_rejects_queries, it would be useful to have another variable, setting which should reject queries for that node.

This can be useful if someone wants to manually run maintenance on the node like mysqldumps and don't want to tinker with load balancer etc.

Related discussion here http://www.mysqlperformanceblog.com/2013/05/02/galera-flow-control-in-percona-xtradb-cluster-for-mysql/#comment-1736303

Alex Yurchenko (ayurchen) wrote :

Raghavendra, how about read-only? Doesn't that fit the bill?

Ovais Tariq (ovais-tariq) wrote :

But then if the node rejects queries then how is mysqldump going to run?

Ovais Tariq (ovais-tariq) wrote :

I was also thinking about a use-case where I can do maintenance on the node such that the maintenance work does not affect other nodes in the cluster. For example i could be doing a backup on the node using xtrabackup and that can consume a lot of IO and thats going to affect the whole cluster. There can be other cases, for example running mysqldump can also cause issues that can affect other nodes because if one node can't keep up its going to affect other nodes.

Alex Yurchenko (ayurchen) wrote :

Ovais, so ideally there should be a command to desync the node from the cluster. However it is different from _rejecting_ queries, which is the topic of this ticket (which I think is Not A Good Idea).

Yes, thats right. While #2 would be interesting to have, the
issue here is from load-balancer's/applications's perspective.

Changed in percona-xtradb-cluster:
milestone: none → 5.5.31-25
assignee: nobody → Raghavendra D Prabhu (raghavendra-prabhu)
Changed in percona-xtradb-cluster:
status: New → Fix Committed
Jervin R (revin) wrote :

Raghu,

So what was the fix that was committed here? :-)

Jervin R (revin) wrote :

Ok found it, http://bazaar.launchpad.net/~raghavendra-prabhu/percona-xtradb-cluster/pxc-1179805/revision/442

So how would this affect the node participation in the cluster?

Changed in percona-xtradb-cluster:
status: Fix Committed → Fix Released
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