MySQL Ndb Cluster provides durability for data by default via logging and checkpointing.

In addition, users can take backups at any time, which allows for disaster recovery, replication synchronisation, data portability and other use cases.

This post looks at the backup and restore mechanisms in MySQL Ndb Cluster.

MySQL Ndb Cluster architecture recap

MySQL Ndb Cluster is a distributed SQL relational database :

• Designed for low overhead read + write scale out, high availability, high throughput and low latency.
• Providing distributed parallel joins, transactions, row locks, foreign keys.
• Data is primarily stored and managed by a set of independent data node processes.
• Data is accessed via distributed MySQL servers and …

MySQL 8.0.22 was released roughly a week ago. It includes some nice additions to replication that we would like to call out. Here they are:

• Automatic Asynchronous Replication Connection Failover (WL#12649). This work, by Hemant Dangi, implements a mechanism in asynchronous replication that makes the replica automatically try to re-establish an asynchronous replication connection to another replication source, in case the current connection gets interrupted;
• New terminology for replica related statements (WL#14171).

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The amount of transactions committed is an important information, but how could you return an accurate value?

This is a question I got from my colleague Ivan, he was challenging with global status values like COM_COMMIT or HANDLER_COMMIT, then checking in innodb_metrics… but this was not accurate.

In fact depending which storage engine you are using, if binary logs are enabled, if you rollback transactions, if you are using auto_commit, etc… all those parameters influence those values.

So the first question was “What metrics or else should we use ?”. In my opinion, the most accurate “counter” for transactions are the GTIDs.

And this is why I created yet another MySQL Shell plugin that does that calculation:

This plugin is available on my GitHub repository …

This post was first published on Oracle MySQL Blog.

If you are running MySQL on premise, it’s maybe the right time to think about migrating your lovely MySQL database somewhere where the MySQL Team prepared a comfortable place for it to stay running and safe.

This awesome place is MySQL Database Service in OCI. For more information about what MDS is and what it provides, please check this blog from my colleague Airton Lastori.

One important word that should come to your mind when we talk about MDS is SECURITY !

Therefore, MDS endpoint can only be a private IP in OCI. This means you won’t be able to expose your MySQL …

Today we will see how to use MySQL Database Service aka MDS with WordPress.

To achieve this easy task, we will use the architecture we already deployed in this article.

We have then two Compute Instances on OCI, 1 running WordPress (Apache and PHP) and one running MySQL 8.0.

The Plan

This is how we will proceed to migrate to MDS with minimal maintenance time, we will:

1. create a MDS instance
2. verify if the database is ready to act as replication source
3. dump the MySQL instance running on OCI for being migrated to MDS.
4. load the dump in MDS
5. create a user dedicated to the replication
6. create a replication channel on MDS (from OCI to MDS)
7. modify WordPress config to point to MDS

Create a MDS …

I got this question on the “How to Avoid Pitfalls in Schema Upgrade with Percona XtraDB Cluster (PXC)” webinar and wanted to answer it in a separate post.

Will RSU have an effect on GTID consistency if replication PXC cluster to another cluster?

Answer for this: yes and no.

Galera assigns its own GTID for the operations, replicated to all nodes of the cluster. Such operations include DML (

INSERT/UPDATE/DELETE

 ) on InnoDB tables and DDL commands, executed with default TOI method. You can find more details on how GTIDs work in the Percona XtraDB Cluster in this blog post.

However, DDL commands, executed with RSU method, are …

From MySQL 8.0.21 onwards, START GROUP_REPLICATION includes new options which allow a user to specify credentials to be used for distributed recovery. You can now pass credentials when invoking START GROUP_REPLICATION instead of setting them when configuring the group_replication_recovery channel.

START GROUP_REPLICATION command now has the options:

• USER: User name.

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Group Replication enables you to create fault-tolerant systems with redundancy by replicating the system state to a set of servers. Even if some of the servers subsequently fail, as long it is not all or a majority, the system is still available.…

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MySQL Group Replication allows you to create an highly-available replication group of servers with minimum effort. It provides automated mechanisms to detect and respond to failures in the members of the group. The response depends on the characteristics of each failure and it is configurable.…

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Group Replication enables you to create fault-tolerant systems with redundancy by replicating the system state to a set of servers. Even if some of the servers subsequently fail, as long it is not all or a majority, the system is still available.…

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