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.

To copy a MySQL server to another server or to the cloud, there are several ways. We can distinguish between two different types of copy: The physical copy is often the fastest. However, it requires some tools to ensure that you have a consistent online backup. For example, you can use MySQL Enterprise Backup (MEB). […]

To copy a MySQL server to another server or to the cloud, there are several ways.

We can distinguish between two different types of copy:

• physical copy
• logical copy

The physical copy is often the fastest. However, it requires some tools to ensure that you have a consistent online backup. For example, you can use MySQL Enterprise Backup (MEB).

Alternatively, it’s possible to use the CLONE plug-in to provision a new instance with existing data from a source server. This is my preferred approach.

Finally, the last physical solution is the use of a file system snapshot, but this requires the right infrastructure and even more care to have a consistent …

Whenever you install your favorite MySQL server on a freshly created Ubuntu instance, you start by updating the configuration for MySQL, such as configuring buffer pool, changing the default datadir director, and disabling one of the most outstanding features – query cache. It’s a nice thing to do, but first things first. Let’s review the best practices we usually follow in Managed Services before using your MySQL server in production and stage env, even for home play purposes.

Memory

Our usual recommendation is to use specific memory parameters, which we suggest to ensure optimal performance.

• To prevent out-of-memory (OOM) episodes, the OOM Score has to be set to -800.
• vm.swappiness = 1
• Disable Transparent Huge Pages
• Install and enable jemalloc. Let’s briefly go through each setting to understand why adjustments are needed. Afterward, we will see how to configure these …

OpenLampTech continues to publish great content for the PHP, MySQL, LAMP stack, and open-source communities. This week, I (am resharing) have another awesome text-based developer interview for you with Wendell Adriel. Thanks for reading!

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Visit and read Wendell’s fantastic interview here: https://openlamptech.substack.com/p/openlamptech-developer-interview-18d

If you’re not already …

This blog post discusses the limitations of the MySQL Clone plugin.

The MySQL clone plugin significantly simplifies the process of replica provisioning. All you need to do is:

• Ensure that the source server has binary logs enabled
• Grant appropriate permissions
• Execute the CLONE INSTANCE  command on the recipient

This works extremely easily when you provision a new replica that doesn’t have any data.

Due to its simplicity, you may want to use the clone plugin instead of a backup to restore a server that survives data inconsistency or corruption. E.g., after crash.

However, if you have data on your replica, you need to consider how you will recover if the CLONE INSTANCE  command fails with an error.

CLONE INSTANCE  command, by default, works as follows:

• Checks prerequisites on the replica
• Wipes out data …