Showing entries 1 to 10 of 966
10 Older Entries »
Displaying posts with tag: Insight for DBAs (reset)
Restrict MySQL Connections to Broken Replica in ProxySQL

ProxySQL is a high-performance SQL proxy, which runs as a daemon watched by a monitoring process. The process monitors the daemon and restarts it in case of a crash to minimize downtime.

The daemon accepts incoming traffic from MySQL clients and forwards it to backend MySQL servers.

The proxy is designed to run continuously without needing to be restarted. Most configurations can be done at runtime using queries similar to SQL statements in the ProxySQL admin interface. These include runtime parameters, server grouping, and traffic-related settings.

Here, we will consider ProxySQL configured for async replication. Even when a replica is broken/stopped, ProxySQL still routes connections to replicas. It can be overcome by setting the appropriate value for mysql-monitor_slave_lag_when_null

[Read more]
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 …
[Read more]
Avoid Surprises When Restarting MySQL — Ensure Dynamic Changes Won’t Be Lost

If you’re a DBA, one of your “easiest” tasks is to stop/start MySQL during a maintenance window, but even that could lead to unwanted scenarios if you modify some dynamic parameters at some point in your instance.

Here’s a brief story of how this could happen, to make it clearer:

You’re a DBA managing a few MySQL servers. The application using one of them starts having issues on a Friday night, right before it’s time to leave; after a quick check, you notice the app is requesting more connections, and the hotfix is to up max connections; you change them dynamically, the fire is off, and so are you. Let your future self worry about finding the root cause and fixing it properly the following Monday.


But life happens; Monday is here with new challenges, and you already forgot about the connections issue… A few months later, a restart for MySQL is required, and surprise, surprise, right after …

[Read more]
Use Physical Backups With MySQL InnoDB Redo Log Archiving

In the world of data backup and security, physical backups play an extremely important role. Physical backup methods are faster than logical because they involve only file copying without conversion. This type of backup is suitable for large, important databases that need to be recovered quickly when problems occur.

Physical backups are the backups that consist of raw copies of the directories and files that store database contents. In addition to databases, the backup can include any related files, such as log or configuration files. Now, since backup speed and compactness are important for busy, important databases, Percona’s open source physical backup solution – Percona XtraBackup (PXB), takes into account all these aspects and benefits MySQL world with its exceptional capabilities!

This blog post will walk you through how PXB …

[Read more]
Complete Walkthrough: MySQL to ClickHouse Replication Using MaterializedMySQL Engine

MySQL is an outstanding open source transactional database used by most web-based applications and is very good at handling OLTP workloads. However, modern business is very much dependent on analytical data. ClickHouse is a columnar database that handles analytical workloads quickly. I recommend you read our previous blog, Using ClickHouse as an Analytic Extension for MySQL, from Vadim to know more about this.

In this blog post, I will show you how to replicate MySQL data in real-time to ClickHouse. I am going to use the MaterializedMySQL engine for this purpose. The blog post contains the following topics.

  • MaterializedMySQL Engine – Overview
  • Prerequisites for the Replication
  • Replication setup
  • Replication testing
  • Understanding ReplacingMergeTree
  • What …
[Read more]
How To Make Schema Changes and Not Die Trying

Schema changes are required to add new features or to fix bugs in an application. However, there is no standard procedure to make the changes in a quick and safe manner. If the changes are not made considering the necessary precautions, you may face unwanted outages on the database that can cause serious problems to your business. In this blog post, I will delve into the most important things to consider while preparing a schema change.

Table size and concurrency

When assessing a schema change, one of the most important things to consider is the table size and concurrency. For small tables, the ALTER operation usually takes a few milliseconds up to a few seconds. Here is where concurrency plays another important role: if the table has periods of low concurrency during the day and the application allows having it locked for a few seconds or minutes, then it is also a good idea to consider a direct ALTER during that period of time. …

[Read more]
Auto-Increment Counter Persistence in MySQL 8: Comparing the Evolution From MySQL 5.7

The auto-increment feature, which generates unique values for primary key columns, is an integral part of the database’s design. With the release of MySQL 8, a notable enhancement was introduced to the auto-increment counter. Compared to MySQL 5.7, this enhancement ensures that the maximum auto-increment counter value persists between server restarts, providing enhanced consistency and reliability in data management. In this article, we will look into this enhancement, compare MySQL 5.7 with MySQL 8, and provide practical examples to demonstrate the differences.

Auto-increment in MySQL 5.7

In MySQL 5.7, the auto-increment counter works as follows: when a new row is inserted into a table with an auto-increment column, the counter increments by 1, and the generated value is used for the primary key of the inserted row. This counter value is stored in memory and is not persistent across server restarts. As a result, if the server …

[Read more]
Understanding MySQL Triggers: Exploring How Triggers Impact MySQL Memory Allocation

This blog was originally published in November 2021 and was updated in September 2023.

MySQL server performance can sometimes be perplexing, and if you’ve ever wondered about the role of triggers in influencing your MySQL server’s memory allocation, this post is for you. MySQL triggers are a powerful tool for database administrators and developers, enabling them to automate tasks, enforce data consistency, and respond to events within the database seamlessly.

Here, we first cover the basics of MySQL Triggers, and then we take a deeper dive, exploring their impact on memory usage and providing strategies to optimize MySQL server performance.

What is a Trigger in MySQL?

A Trigger in MySQL is a database object that plays a pivotal role in database management. It is essentially a set of instructions or a program that is executed automatically in response to specific events or actions occurring within the …

[Read more]
Failover and Recovery Scenarios in InnoDB Cluster and ClusterSet

This blog post will focus on failover and recovery scenarios inside the InnoDB Cluster and ClusterSet environment. To know more about the deployments of these topologies, you can refer to the manuals – InnoDB Cluster and Innodb ClusterSet setup.

In the below snippet, we have two clusters (cluster1 and cluster2), which are connected via an async channel and combined, known as a ClusterSet topology. We are going to use the below topology in all of our cases.

MySQL ssl  JS > myclusterset.status({extended: 1})
    "clusters": {
        "Cluster1": {
            "clusterRole": "PRIMARY", …
[Read more]
The Deprecation of qpress/QuickLZ Compression Algorithm

To reduce the backup size, save storage space, and speed up the backup and restore process, you can compress a backup with Percona XtraBackup. The XtraBackup --compress option makes XtraBackup compress all output data, including the transaction log file and metadata files, with one of the supported compression

[Read more]
Showing entries 1 to 10 of 966
10 Older Entries »