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Displaying posts with tag: General (reset)
MySQL 8.0: if I should optimize only one query on my application, which one should it be ?

Answering this question is not easy. Like always, the best response is “it depends” !

But let’s try to give you all the necessary info the provide the most accurate answer. Also, may be fixing one single query is not enough and looking for that specific statement will lead in finding multiple problematic statements.

The most consuming one

The first candidate to be fixed is the query that consumes most of the execution time (latency). To identify it, we will use the sys schema and join it with events_statements_summary_by_digest from performance_schemato retrieve a real example of the query (see this post for more details).

Let’s take a look at what sys schema has to offer us related to our mission:

> show tables like …
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Migrate from a single MySQL Instance to MySQL InnoDB Cluster using CLONE plugin

When somebody wants to migrate from a single MySQL instance to a full HA solution using MySQL InnoDB Cluster, the best solution to reduce the downtime is to use asynchronous replication and switch database only once at a certain point in time when everything is ready. This is almost what I explained already in this post.

The most difficult part was related to the provisioning of the existing data to the new cluster members. A backup (physical or logical) was required. It should have been restored on every nodes and we had to be sure to not mess up with the GTIDs.

This is not more the case since MySQL 8.0.17 ! Now we can use the CLONE plugin to start the cluster provisioning too.

The current situation

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MySQL InnoDB Cluster, automatic provisioning, firewall and SELinux

You may have noticed that in many of my demos, I disable firewall and SELinux (I even use --initialize-insecure sometimes ). This is just to make things easier… But in fact enabling iptables and SELinux are not complicated.

Firewall

These examples are compatible with Oracle Linux, RedHat and CentOS. If you use another distro, the principle is the same.

For the firewall, we need first to allow incoming traffic to MySQL and MySQL X ports: 3306 and 33060:

# firewall-cmd --zone=public --add-port=3306/tcp --permanent
# firewall-cmd --zone=public --add-port=33060/tcp --permanent

If you don’t plan to restart the firewall, you just need to run the same commands without --permanent to make then immediately active.

Then we need to allow the Group Replication’s communication port. This is usually 33061 but it can be configured in …

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MySQL 8.0.17 and Drupal 8.7

From Drupal’s website, we can see that now the support of MySQL 8 is ready.

I just tested it and it works great !

The only restriction is related to PHP and the support for the new authentication method in php-mysqlnd.

In this previous post, I was happy because it was included in PHP 7.2.8, but this has been reverted back since then. Currently none of the latest version of PHP 7.x is supporting this authentication method.

We can easily verify this, first with the PHP version provided by default in Oracle Linux 8:

# php -i | grep "Loaded plugins\|PHP Version " | tail -n2
PHP Version => 7.2.11
Loaded plugins => mysqlnd,debug_trace,auth_plugin_mysql_native_password, …
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Create an Asynchronous MySQL Replica in 5 minutes

I have already posted some time ago a post related to the same topic (see here).

Today, I want to explain the easiest way to create an asynchronous replica from an existing MySQL instance, that this time has already data !

The Existing Situation and the Plan

Currently we have a MySQL server using 8.0.17 and GTID enabled on mysql1. mysql2is a single fresh installed instance without any data.

The plan is to create a replica very quickly and using only a SQL connection.

Preliminary Checks

First we verify that mysql1 has GTID enabled. If not we will enable them:

mysql> select @@server_id,@@gtid_mode,@@enforce_gtid_consistency;
+-------------+-------------+----------------------------+
| @@server_id | @@gtid_mode | @@enforce_gtid_consistency | …
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Overview on MySQL Shell 8.0.17 Extensions & Plugins and how to write yours !

With MySQL Shell 8.0.17, a super cool new feature was released: the MySQL Shell Extensions & Plugins !

You will be able to write your own extensions for the MySQL Shell. You may already saw that I’ve written some modules like Innotop or mydba for MySQL Shell.

However those plugins were written in Python and only accessible in Python mode. With the new Shell Extensions Infrastructure, this is not the case anymore.

Also, this allows you to populate the help automatically.

Extensions are available from the extglobal object.

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MySQL InnoDB Cluster from scratch – even more easy since 8.0.17

Create a MySQL InnoDB Cluster using MySQL 8.0 has always been very easy. Certainly thanks to MySQL Shell and server enhancements like SET PERSIST and RESTART statement (see this post).

The most complicated part to deal with was the existing and none existing data. In fact GTID sets must be compatible.

Let me explain that with some examples:

Example 1 – empty servers

If you have empty servers with GTID enabled, manually creating credentials to connect to each MySQL instances will generate GTIDs that will prevent nodes to …

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Some queries related to MySQL Roles

MySQL Roles are becoming more and more popular. Therefor, we receive more and more questions related to them.

First I encourage you to read this previous 2 posts:

In this post, I will share you some queries I find useful when using MySQL Roles.

Listing the Roles

The first query allows you to list the Roles created on your MySQL Server and if they are assigned to users, and how many:

SELECT any_value(User) 'Role Name', 
       IF(any_value(from_user) is NULL,'No', 'Yes') Active,
       count(to_user) 'Assigned  …
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About MySQL and Indexes

MySQL supports different types of Indexes. They depend on the storage engine and on the type of data. This is the list of supported indexes:

Best Practices

My recommendation are valid for InnoDB storage engine. I won’t talk about MyISAM. There are some best practices to follow when designing your tables. These are the 3 most important:

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the MySQL Team in Austin, TX

At the end of the month, some engineers of the MySQL Team will be present in Austin, TX !

We will attend the first edition of Percona Live USA in Texas.

During that show, you will have the chance to meet key engineers, product managers, as well as Dave and myself.

Let me present you the Team that will be present during the conference:

The week will start with the MySQL InnoDB Cluster full day tutorial by Kenny and myself. This tutorial is a full hands-on tutorial where we will start by migrating a classical asynchronous master-replicas topology to a new MySQL InnoDB Cluster. We will then experience …

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