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Displaying posts with tag: Replication (reset)
Making my MySQL InnoDB Cluster safe from naughtiness

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", …
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MySQL 8.3: Purging data from your InnoDB Cluster

Maintaining a production dataset at a manageable size can present a considerable challenge during the administration of a MySQL InnoDB Cluster.

Old Days

Back in the day when we only had one main copy of our data (the source), and one read copy (the replica) that we used to look at current and old data from our main system, we used a special trick to remove data without affecting the replica. The trick was to turn off writes to the binary log for our removal commands in the main system. External tools like pt-archiver were also able to use that trick. To stop bypass writing into the binary log, we used the command: SET SQL_LOG_BIN=0.

This mean that on the main production server (replication source), we were purging the data without writing the delete operation into the binary logs:

Current Days

These …

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WordPress in OCI with MySQL HeatWave Read Replicas and MySQL Router R/W Splitting

Some time ago, we saw how we could deploy WordPress on OCI using MySQL HeatWave Database Service with Read Replicas. We had to modify WordPress to use a specific plugin that configures the Read/Write Splitting on the application (WordPress): LudicrousDB.

Today, we will not modify WordPress to split the Read and Write operations, but we will use MySQL Router 8.2.0 (see [1], [2], [3]).

Architecture

The …

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How to Read Simplified SHOW REPLICA STATUS Output

As a MySQL database administrator, you’re likely familiar with the SHOW REPLICA STATUS command. It is an important command for monitoring the replication status on your MySQL replicas. However, its output can be overwhelming for beginners, especially regarding the binary log coordinates. I have seen confusion amongst new DBAs on which binary log file and position represent what in the replication.

In this guide, we’ll simplify the SHOW REPLICA STATUS output, focusing on the critical binary log coordinates essential for troubleshooting and managing replication.

The key binlog coordinates

Before we delve into the output, let’s understand the key binlog coordinates we’ll be working with:

  • Master_Log_File: This is the name of the primary binary log file that the I/O thread is currently reading from.
  • Read_Master_Log_Pos: It represents the …
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MySQL 8 and Replication Observability

Many of us, old MySQL DBAs used Seconds_Behind_Source from SHOW REPLICA STATUS to find out the status and correct execution of (asynchronous) replication.

Please pay attention of the new terminology. I’m sure we’ve all used the old terminology.

However, MySQL replication has evolved a lot and the replication team has worked to include a lot of useful information about all the replication flavors available with MySQL.

For example, we’ve added parallel replication, group replication, … all that information is missing from the the good old SHOW REPLICA STATUS result.

There much better ways to monitoring and observing the replication process(es) using Performance_Schema.

Currently in Performance_Schema, there are 15 tables relating to replication instrumentation:

+------------------------------------------------------+
| …
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InnoDB ClusterSet Deployment With MySQLRouter

This blog post will cover the basic setup of the InnoDB ClusterSet environment, which provides disaster tolerance for InnoDB Cluster deployments by associating a primary InnoDB Cluster with one or more replicas in alternate locations/different data centers. InnoDB ClusterSet automatically manages replication from the primary cluster to the replica clusters via a specific ClusterSet Async replication channel. If the primary cluster becomes inaccessible due to a loss of network connectivity or a data center issue, you can make a replica cluster active in its place.

Now, let’s see in detail how exactly we can configure the topology.

We have used the sandbox environment available via MySQLShell utility for this setup.

Environment

Cluster1:
         127.0.0.1:3308
         127.0.0.1:3309
         127.0.0.1:3310

Cluster2:
         127.0.0.1:3311
         127.0.0.1:3312
         127.0.0.1:3313

Router: …
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An Introduction to MySQL Replication: Exploring Different Types of MySQL Replication Solutions

This blog was originally published in February 2017 and was updated in September 2023.

In this blog post, I provide an in-depth introduction to MySQL Replication, answering what it is, how it works, its benefits and challenges, as well as reviewing some of the MySQL replication concepts that are part of the MySQL environment (and Percona Server for MySQL specifically). I will finish by also clarifying some of the common misconceptions people have about replication and how Percona can help.

Since I’ve been working on the Solution Engineering team, I’ve noticed that – although information is plentiful – replication is often misunderstood or incompletely understood.

What is MySQL Replication?

MySQL replication is …

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As a DBA, develop a critical mind when receiving advice

On the Internet, you can get a lot of advice from almost anywhere when you’re looking for information on how to do your DBA job.

My blog is one of these sources of advice, and depending on the source, we generally trust the advice more or less.

But sometimes advice doesn’t take the whole picture into account, and even if it comes from a recognized authority, it can lead to more or less serious problems.

Let’s consider the following situation:

We have an InnoDB ReplicaSet with 1 replication source (primary) and 2 replicas:

 JS > rs.status()
{
    "replicaSet": {
        "name": "myReplicaSet", 
        "primary": "127.0.0.1:3310", 
        "status": "AVAILABLE", 
        "statusText": "All instances available.", 
        "topology": {
            "127.0.0.1:3310": {
                "address": "127.0.0.1:3310", 
                "instanceRole": "PRIMARY", 
                "mode": "R/W", …
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Moodle on OCI with MySQL HeatWave: Extended Architectures – part 2

To continue our journey to Moodle on Oracle Cloud Infrastructure using Ampere compute instances and MySQL HeatWave Database Service [1] [2], in this article we will see how to scale our architecture using multiple Moodle instances, High Availability for the Database and Read Scale-Out.

This is the architecture we will deploy:

The same principles can be applied to other projects, not just Moodle.

Multiple Compute Instances & MySQL HeatWave High Availability

The first step is to use again the Stack to deploy the initial resources. We must insure that we use a MySQL Shape that has at least 4 OCPUs

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Moodle on OCI with MySQL HeatWave: Extended Architectures – part 1

In the previous post, we saw how to quickly deploy Moodle to Oracle Cloud Infrastructure on Ampere compute instances and using MySQL HeatWave.

In this post, we will explore some other features and the benefits of running on OCI and MySQL HeatWave to extend our architecture dedicated to Moodle in the Cloud.

Read Replicas

Moodle natively offers the possibility of distributing the load between reads and writes. When using MySQL HeatWave Database Service, adding read replicas is also a very easy task. Let’s see how we can benefit from it.

To be able to use MySQL HeatWave Read Replicas, the MySQL shape must have at least 4 OCPUs.

Let’s modify the moodle stack and deploy it again but this time we choose a bigger shape for MySQL:

When everything is ready, …

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