Hello friends, at Percona Managed Services, we usually do different types of things every day, including routine tasks, monitoring, and, very frequently, answering questions that are not always easy to answer.

A few days ago, a client asked us the following question: “Hey Percona, I have a question and a problem simultaneously: I want to delete rows from a table from a specific date back because the data is not necessary. I tried to run the DELETE command, which gave me this error: Cannot delete or update a parent row: a foreign key constraint fails. Could you please help me?”

At first glance, the error message was obviously clear: the table from which rows were to be deleted had a child table, which prevented the execution of the DELETE directly.

“Don’t worry, we’ll take a look at the issue, and …

Public cloud spending is slowing down. Quarter-over-quarter growth is no longer hitting 30% gains for AWS, Google, and Microsoft. This is businesses’ response to tough and uncertain macroeconomic conditions, where organizations scrutinize their public cloud spending to optimize and adjust.

In this blog post, we will see how running databases on Kubernetes with Percona Operators can reduce your cloud bill when compared to using AWS RDS.

Inputs

These are the following instances that we will start with:

• AWS
• RDS for MySQL in us-east-1
• 10 x db.r5.4xlarge
• 200 GB storage each

The cost of RDS consists mostly of two things – compute and storage. We will not consider data transfer or backup costs in this article.

• db.r5.4xlarge – $1.92/hour or …

Oracle’s MySQL 5.7 has had a good, long run, but the official End of Life is October of 2023. The Era of MySQL 5.x will be over, and only MySQL 8.0 will be officially supported. Yup, six months away. So if you are running MySQL, you need to consider upgrading to version 8.0 N-O-W!!

What does an upgrade provide?

MySQL 8.0 has many really cool features and improvements that are well worth the upgrade. The default character set of UTF8MB4 gives Unicode version 9.0 support. So you get the Umaluts, Cedils, and C-J-K Language support in your data, plus emojis. 8.0 is optimized around this character set. This gives you all the international characters you probably need to support global operations.

The Structured Query Language has been greatly enhanced. If you have trouble writing subqueries, you rejoice in lateral-derived joins and Common Table Expressions (CTEs). There is a new intersect clause to aid with sets. …

Introduction/TLDR:

We are considering changing EXPLAIN in Percona Server for MySQL to require less privileges for providing execution plans for INSERT/UPDATE/DELETE statements (and possibly changing the behavior for EXPLAIN SELECT as well), to make it more convenient and safer to use with monitoring and query analysis tools. We would like to get feedback from the Community about the different approaches for achieving this.

The problem:

Running EXPLAIN is a great way to understand how complex SQL statements are executed. So it is natural that monitoring and query analysis tools utilize EXPLAIN for these purposes.

However, there is a problem for cases when INSERT/UPDATE/DELETE statements need to be explained. Running EXPLAIN for these statements, a read-only operation, requires the same privileges as running the original statements …

Previously, I wrote about our Terraform provider to deploy Percona Server for MySQL (Percona Server for MySQL: Automatic Cloud Deployment With Terraform) and Percona Monitoring and Management (Deploying Percona Monitoring and Management (PMM) With Terraform). Now we also added the capability to deploy Group Replication configuration with Percona Server for MySQL, and assuming we have PMM installed (see previous post), we also can automatically add Group Replication nodes to PMM monitoring.

resource "percona_ps" "psgr" {
  count = 1
  instance_type            = "t3.micro" # for AWS
  key_pair_name            = "sshKey1"
  password                 = "password"
  replication_type         = "group-replication" …

Percona XtraBackup is an open source hot backup utility for MySQL-based servers. To take consistent and hot backup, it uses various locking methods, especially for non-transactional storage engine tables. This blog post discusses the cause and possible solution for queries with ​Waiting for table flush state in processlist when taking backups using Percona XtraBackup. Only MySQL 5.7 version is affected by this, as per my tests.

Type of locks taken by Percona XtraBackup

Before discussing the main issue, let’s learn about the type of locks used by Percona XtraBackup to take consistent backups. Percona XtraBackup uses backup locks as a lightweight alternative to FLUSH TABLES WITH READ LOCK. This feature is …

Amazon instance profiles are used to pass IAM roles to an EC2 instance. This IAM role can be queried using EC2 instance metadata to access an S3 bucket. Please check Amazon’s Official Documentation for more information.

Today we are happy to announce that starting with Percona XtraBackup 8.0.31-24, xbcloud can read instance metadata and fetch credentials from an instance profile, utilizing it to authenticate against an S3 bucket. Xbcloud is a tool part of Percona XtraBackup and allows you to upload and download backups to Amazon S3 storage.

How it works

Configure your EC2 instance …

We had a couple of cases where clients reported that the MySQL error log was flooded with the below note:

2023-01-18T13:07:56.946323Z 2 [Note] InnoDB: Stopping purge
2023-01-18T13:07:56.948621Z 2 [Note] InnoDB: Resuming purge
2023-01-18T13:08:27.229703Z 2 [Note] InnoDB: Stopping purge
2023-01-18T13:08:27.231552Z 2 [Note] InnoDB: Resuming purge
2023-01-18T13:08:28.581674Z 2 [Note] InnoDB: Stopping purge

One of my colleagues Sami Ahlroos found that whenever we trigger a truncate on any table, the function is stopping the purge and then resuming it once it has found it stopped.

Below are the steps to reproduce.

1. Log verbosity needs to be set to 3 (the default value)

mysql> show variables like 'log_error_verbosity%';
+---------------------+-------+
| Variable_name       | Value |
+---------------------+-------+
| …

How can we fix a nasty out-of-space issue leveraging the flexibility of Percona Operator for MySQL?

When planning a database deployment, one of the most challenging factors to consider is the amount of space we need to dedicate to data on disk.

This is even more cumbersome when working on bare metal, as it is more difficult to add space when using this kind of solution with respect to the cloud.

When using cloud storage like EBS or similar, it is normally easy(er) to extend volumes, which gives us the luxury to plan the space to allocate for data with a good grade of relaxation. 

Is this also true when using a solution based on Kubernetes like Percona Operator for MySQL? Well, it depends on where you run it. However, if the platform you choose supports the option to extend volumes, K8s per se gives you the …

Recently, we performed a database engine major version upgrade in one of our customers’ environments from MySQL 5.7.26 to 8.0.27. After this version upgrade, we experienced issues with backups and replication for one of the nodes.

In this article, I will explain these issues in detail and recommend a way to take backups from a replication environment.

To begin with, we upgraded all the database nodes from 5.7.26 to 8.0.27 and as a recommended way we have a backup set-up from one of the replica nodes. Physical backups are being taken using Percona XtraBackup (PXB) so it does not lock the database during the backup.

With MySQL 5.7, a backup was taken using PXB 2.4. Due to the new data dictionaries, redo log and undo log in MySQL 8.0, we also upgraded PXB to 8.0.27 to avoid …