In this blog post, we’ll review how to run Linux profilers such as perf and produce flame graphs on Kubernetes environments.

Flame graphs are a graphical representation of function calls. It shows which code paths are more busy on the CPU in given samples. They can be generated with any OS profiler that contains stack traces such as perf, eBPF, and SystemTap.

An example of a flame graph can be found below:

Each box is a function in the stack, and wider boxes mean more time the system was busy on CPU on these functions.

Kubernetes limitations

In Linux, by default, performance system events can’t be collected by unprivileged users. In regular environments, this can be easily worked around by running the profiler with a sudo privilege.

On the other hand, in Kubernetes environments, pods are the smallest deployable unit that consists of one or more containers. Exploits are generally targeted to …

Let’s see how to deploy WordPress and MySQL on a Kubernetes Cluster. The Kubernets cluster we are using is OKE (Oracle Kubernetes Engine) in OCI (Oracle Cloud Infrastructure):

OKE Cluster

We start by creating a Kubernetes Cluster on OCI using the Console:

We select the Quick create mode:

We need to name our cluster and make some choices:

When created, we can find it in the OKE Clusters list:

And we can see the pool of workers nodes and the workers:

kubectl

I like to use kubectl directly on my latop to manage my K8s Cluster.

On my Linux Desktop, I need to install kubernetes-client package (rpm).

Then on the K8s Cluster details, you can click on Access Cluster to get all the commands to use:

We need to copy them on our terminal and then, I like to also enable the bash completion for …

This blog post discusses roles in MySQL 8.0, which are named collections of privileges. Like user accounts, roles can have privileges granted and revoked as required.

Typically, we have multiple users with the same set of privileges. Previously, the only way to grant and revoke privileges to multiple users was to change the privileges of each user individually, which was time-consuming. To make it easier, MySQL provided a new object called role. A role is a named collection of privileges.

Here are the primary SQL commands that we will be discussing in relation to managing MySQL roles:

CREATE ROLE and DROP ROLE create and remove roles.
GRANT and REVOKE assign privileges to revoke privileges from user accounts and roles.
SHOW GRANTS displays privilege and role assignments for user accounts and roles.
SET DEFAULT ROLE specifies which account roles are active by default.
SET ROLE changes the active roles within the current session.
The …

Performing an operation is always challenging when dealing with K8s.

When on-prem or DBaaS like RDS or Cloud SQL, it is relatively straightforward to apply a change. You can perform a DIRECT ALTER, use a tool such as pt-osc, or even, for certain cases where async replication is in use, perform changes on replicas and failover.

In this blog post, I’ll provide some thoughts on how schema changes can be performed when running MySQL on Kubernetes

I won’t focus on DIRECT ALTERs as it is pretty straightforward to apply them. You can just connect to the MySQL service POD and perform the ALTER.

But how can we apply changes in more complex scenarios where we may want to benefit from pt-osc, gain better control over the operation, or take advantage of the K8s features?

One convenient way that I’ve found …

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Transparent Huge Pages (THP) is a memory management feature in Linux operating systems that aims to enhance system performance. While THP can be beneficial for many applications, enabling it on a database server could have unintended consequences. In this post, we will explore THP, its impact on database servers, and how to disable it for optimal performance and stability.

What are Transparent Huge Pages?

In order to understand THP, we should first start with a brief description of Linux HugePages. The concept of HugePages in Linux has existed for many years, first introduced in 2007. By default, the majority of widely used Linux distributions employ a virtual memory page size of 4KB. However, the inclusion of the HugePages feature allows the Linux kernel to efficiently handle substantial memory pages alongside the standard 4KB size.

In order for an application to utilize HugePages, however, it must explicitly include an …

This post was originally published in 2011 and was updated in October 2023.

I see this message on our forums, and I think it’s a great question: “Which version of Percona Server is currently recommended?” It’s really the same question as “Which version of MySQL is currently recommended?” In this blog, we cover everything you need to know about how to choose the right version of MySQL for your needs, as well as key information on the latest versions, 5.7 and 8.0.

Understanding MySQL Versions

MySQL versions play a pivotal role in database management, as each MySQL version represents a distinct release, encompassing enhancements, bug fixes, and new features that affect the performance, security, and functionality of the database and applications. Staying informed about MySQL version updates is vital for anyone tasked with managing databases, as it directly impacts the efficiency and reliability of data …

This article will explore how to connect to Oracle in Delphi using the Devart ODAC library. We'll cover the installation of Devart ODAC, provide concrete examples of its usage, and even compare it to FireDAC.

The post How to Connect to Oracle in Delphi with Devart ODAC appeared first on Devart Blog.

As a DBA, one of the very frequent tasks is to stop/start MySQL service for batching or some other activities. Before stopping MySQL, we may need to check if there are any active connections; if there are, we may need to kill all those. Generally, we use pt-kill to kill the application connections or prepare kill statements using the select queries.

Example commands:

pt-kill --host=192.168.11.11 --user=percona -p --sentinel /tmp/pt-kill.sentinel2 --pid /tmp/pt-kill.pid  --victims all --match-command 'Query' --ignore-user 'pmm|rdsadmin|system_user|percona' --busy-time 10 --verbose --print --kill 

select concat('kill ',id,';') from information_schema.processlist where user='app_user';

MySQL has a variable called offline_mode to set the server into maintenance mode. When you set this, it immediately disconnects all the client connections that don’t …

We will provide step-by-step instructions on installing MyDAC, demonstrate its usage with practical examples, and compare it with FireDAC to highlight its advantages.

The post How to Connect to MySQL in Delphi with MyDAC: A Comprehensive Guide appeared first on Devart Blog.