MySQL 8.0.16 has been released last Thursday. In it, you can find some new replication features. Here is a quick summary. Follow-up blog posts will provide details about these features.
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We saw yesterday that when an issue (like network splitting), it’s possible to remain with a partitioned cluster where none of the partition have quorum (majority of members). For more info read how to manage a split-brain situation.
If your read the previous article you notice the red warning about forcing the quorum. As an advice is never too much, let me write it down again here : “Be careful that the best practice is to shutdown the other nodes to avoid any kind of conflicts if they reappear during the process of forcing quorum“.
But if some network problem is happening it might not be possible to shutdown those other nodes. Would it be really bad ?
YES !
Split-Brain
Remember, we were in this situation:
We …
[Read more]MySQL InnoDB Cluster - HowTo #1 - Monitor your cluster
Q: How do I monitor the status & the configuration of my cluster?
A: Use status() or status({extended:true}) or status({queryMembers:true})?
Everywhere I go to present MySQL InnoDB Cluster, during the demo of creating a cluster, many people doesn’t understand why when I’ve 2 members, my cluster is not yet tolerant to any failure.
Indeed when you create a MySQL InnoDB Cluster, as soon as you have added your second instance, you can see in the status:
"status": "OK_NO_TOLERANCE","statusText": "Cluster is NOT tolerant to any failures.",
Quorum
Why is that ? It’s because, to be part of primary partition (the partition that holds the service, the one having a Primary-Master in Single Primary Mode, the default mode), your partition must reach the majority of nodes (quorum). In MySQL InnoDB Cluster (and many other cluster solutions), to achieve quorum, the amount of members in a partition must be > (bigger) than 50%.
So when we have 2 nodes, if there is a network issue between the …
[Read more]Consistency during reads have been a small concern from the adopters of MySQL InnoDB Cluster (see this post and this one).
This is why MySQL supports now (since 8.0.14) a new consistency model to avoid such situation when needed.
Nuno Carvalho and Aníbal Pinto already posted a blog series I highly encourage you to read:
[Read more]MySQL InnoDB Cluster is evolving very nicely. I realized that the MySQL Shell also improved a lot and that it has never been so easy to setup a cluster on 3 new nodes.
This is a video of the updated procedure on how to install MySQL InnoDB Cluster on GNU Linux rpm based (Oracle Linux, RedHat, CentOS, Fedora, …)
On previous posts about Group Replication consistency we:
In blog 3. we presented the consistency levels: EVENTUAL, BEFORE, AFTER and BEFORE_AND_AFTER; their scopes: SESSION, GLOBAL; and their context: whether they only impact the ongoing transaction or all concurrent transactions.…
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[Read more]This was not on the radar. I have never been proficient in Galera clusters and related technologies, and thus I hadn’t given much thought to Percona Xtradb Cluster (PXC), until Alkin approached me at FOSDEM, and proposed to extend dbdeployer features to support PXC. He mentioned that many support engineers at Percona use dbdeployer) on a daily basis and that the addition of PXC would be welcome.
I could not follow up much during the conference, but we agreed on …
[Read more]Some months ago, Shlomi Noach published a series about Service Discovery. In his posts, Shlomi describes many ways for an application to find the master. He also gives detail on how these solutions cope with failing-over to a slave, including their integration with Orchestrator.
This is a great series, and I recommend its reading for everybody implementing master failover, with or without
This event was just awesome. We got 110 participants ! Thank you everybody and also a big thank to the speakers.
Here are the slides of all the sessions:
