I’m just trying out the v8.4 Read-Write configuration for MySQL Router, that comes default in the community edition and, as they say, TL;DR “it’s default upon bootstrap”.

What does this mean and how can I go about it?

The overview is simple:

• Either install or upgrade your existing MySQL Router to v8.4 at least.
• Bootstrap the Router.
• Use the port 3310 or change it to fit your needs.

Let’s get to it:

Stop your running router:

systemctl stop mysqlrouter

Copy the old config, just in case:

cp /etc/mysqlrouter/mysqlrouter.conf /etc/mysqlrouter/mysqlrouter_v80.conf

I normally keep my mysql linux repository disabled so no “yum update” takes over version control and gives me a nasty surprise afterwards. As so, I uncomment the “mysql” entry:

vi /etc/yum.conf …

Different ways to get the status:

mysqlsh --login-path=icadmin -h$MYROUTER1 -- cluster status

mysqlsh --login-path=icadmin -h${HOSTNAME} --redirect-primary -- cluster status

mysqlsh icadmin:'P4ssw0rD'@db01:3306 -- cluster status --extended=0

mysqlsh icadmin@$MYROUTER1:3306 -- cluster status --extended=1

watch -n 5 “mysqlsh --login-path=icadmin -h$MYROUTER1 -- cluster status”

Set the Primary Instance (switching):

mysqlsh --login-path=icadmin -h${HOSTNAME} --redirect-primary -- cluster set_primary_instance "db01"

Obtaining MySQL InnoDB Cluster basics:

select cluster_id, cluster_name, description, cluster_type, primary_mode, clusterset_id from mysql_innodb_cluster_metadata.clusters;

Members of our cluster:

select * from performance_schema.replication_group_members order by MEMBER_ROLE;

Local & Remote Trans Q’s:

 …

Some users, myself included, have noticed that their MySQL error log contains many lines like this one: Where does that error come from? The error MY-010914 is part of the Server Network issues like: Those are usually more problematic than the ones we are covering today. The list is not exhaustive and in the source […]

Just thought I’d share a script I use daily and helps me redirect my attention if needed.

This is but a mere pointer, guideline and starting point in any task. I just thought I’d share and hope someone else’s day becomes slightly easier thanks to some brief investigation and command tweaking.

Now the really handy thing here is that I only hard code the router01 node name, as I’m using that as a potential endpoint (thinking cloud, XaaS, etc…) where it could also be a VIP, LBR or similar. It’s the entry point so I can query the P_S table error_log so I can get different views and act accordingly.

For example:

• First, give me the InnoDB Cluster ordered server list so I can take a step back from my usual pains and worries, and see the architecture view. And make me type “Y” or similar to move on. Here if there were any server missing, I’d see the summary right away so I don’t really need to …

I thought I’d share some quick intro steps into how we can monitor the MySQL Router.

This can be useful if we’re observing intermittent outages, network packet drops or you’re just not sure if everythings fine in your MySQL InnoDB Cluster.

My scenario: The drupal servers are connecting and sometimes the users are getting connection errors. I don’0t see anything at MySQL server level of any instance nor cluster problem. Let’s review the Routers.

On all MySQL Router servers, double check the config file for the log location and also the log level. At /etc/mysqlrouter/mysqlrouter.conf (default rpm install location):

[DEFAULT]
name=myrouter
user=mysqlrouter
..
..
logging_folder=/routerlog/log
..
[logger]
level=DEBUG
#level=INFO

I’ve changed my logger level to DEBUG which will give you a lot more info about connections and counters so you can see what’s happening …

Group replication is a fault-tolerant/highly available replication topology that ensures if the primary node goes down, one of the other candidates or secondary members takes over so write and read operations can continue without any interruptions. However, there are some scenarios where, due to outages, network partitions, or database crashes, the group membership could be broken, or we end […]

TL;DR: Make sure to run “SET persist_only disabled_storage_engines=’MyISAM’, persist sql_generate_invisible_primary_key=ON;” on all instances and restart each one in your MySQL InnoDB Cluster.

Ok, what does “safe from naughtiness” mean?:
– Anyone creating tables that aren’t InnoDB, as this doesn’t make sense, after all, it is an “InnoDB” cluster.
– Making sure all tables have a Primary Key (invisible or not).
– Making sure that my (invisible) primary keys are visible to the cluster as it will rightfully complain if they aren’t!

This basically means that once you’ve got it all up and running you won’t run into those horrible situations whereby someone, somewhere, creates a MyISAM table that didn’t have a Primary Key and thus leave you with a broken cluster.

Eg.

MySQL rtnode-01:3306 ssl JS > vlc.status()
{
 "clusterName": "VLC",
 "clusterRole": "PRIMARY", …

Now this is far from being any observability manual for your InnoDB Cluster and let alone go into everything MySQL Shell API Admin, or the collectDiagnostics utility. You can also use the default javascript commands that we all know and love via dba.getCluster() and so on, but here’s a different take.

I just want to share something I’ve been playing with to pull out some key info from mycluster. Hope it helps someone else out there.

General setup:

select cluster_id, cluster_name, description, cluster_type, primary_mode, clusterset_id
from mysql_innodb_cluster_metadata.clusters;

Members of our cluster:

select * from …

Back again, now with MySQL installs. And this means using the MySQL repository this time around.

I’ve been installing and configuring InnoDB Clusters and ClusterSets and thinking about the Ansible and Terraform users amongst us, maybe one-liners might help someone out there.

So, what about if I share how to install the MySQL repo, install the MySQL instance, create an InnoDB Cluster, add a MySQL Router, create a ClusterSet, make sure the Router is ClusterSet-aware, and then test it out. And all via one-liners.

First up, obrigado Miguel for https://github.com/miguelaraujo/ClusterSet-Demo.

To simplify the command execution sequence, these sections aim to help summarize the technical commands required to create the whole platform. And on a default path & port configuration, to ease operational deployments for all those 000’s of installs …

If you use MySQL Shell for Visual Studio Code, using a bastion host is the easiest method to connect to a MySQL HeatWave DB Instance on OCI.

If you already have a connection setup using a bastion to host, you may experience the same problem as me, MySQL Shell complains about an invalid fingerprint detected:

This error has nothing to do with the fingerprint of your user OCI Key. The problem is related to the key of your bastion host as you can see in the output window:

This happens if you have changed your bastion host for example.

To resolve the problem, remove the current ssh host key for the bastion host stored in your know_hosts:

$ ssh-keygen -R "host.bastion.us-ashburn-1.oci.oraclecloud.com"

Use the name of your bastion host of course.

When done, it’s already fixed, you can connect back to your MySQL HeatWave DB Instance using MySQL Shell …