byCarlos Tutte|Mar 27, 2023|Insight for DBAs,MySQL,Percona Software
On MySQL and Percona Server for MySQL, there is a schema called information_schema (I_S) which provides information about database tables, views, indexes, and more. A lot of useful information can be retrieved from this schema, for example, table metadata and foreign...
byCarlos Tutte|Jan 18, 2022|MySQL,Percona Software
使用基于行的副本时最常见的问题tion (RBR) is replication lag due to the lack of Primary keys. The problem is that any replicated DML will do a full table scan for each modified row on the replica. This bug report explains it more in-depth:...
byCarlos Tutte|Sep 16, 2021|Insight for DBAs,MySQL,Percona Software
When doing migrations or failovers in MySQL, there is usually a need to do a topology change and repoint replica servers to obtain replication data from a different server. For example, given servers {A, B, and C} and the following topology: If you need to repoint C...
byCarlos Tutte|Jun 30, 2021|MySQL,Percona Software
The Problem I recently worked on a customer engagement where the customer needed to archive a high amount of rows from different tables into another server (in this example for simplicity I am just archiving the results into a file). As explained in this other...
byCarlos Tutte|Jan 21, 2021|Insight for DBAs,Insight for Developers,MySQL
Although how range_optimizer_max_mem_size operates is explained in the official doc, it’s not a well-known variable and surely not a variable you need to modify under most circumstances. But from time to time we get some performance tickets related to this. What...
byCarlos Tutte|Oct 16, 2020|Insight for DBAs,MySQL,Percona Software
Changing the default value (3) of log_error_verbosity in MySQL/Percona Server for MySQL 5.7 can have a hidden unintended effect! What does log_error_verbosity do exactly? As per the documentation: “The log_error_verbosity system variable specifies the verbosity...
byCarlos Tutte|Aug 12, 2020|Insight for DBAs,Insight for Developers,MySQL,Percona Software
Disclaimer: the following script only works for Percona Server for MySQL 5.7, and relies on enabling performance schema (PS) instrumentation which can add overhead on high concurrent systems, and is not intended for continuous production usage as it’s a POC...
byCarlos Tutte|Jun 19, 2020|Insight for DBAs,Monitoring,Percona Software
Disclaimer: This blog post is about migrating Percona Monitoring and Management 2 (PMM) data between PMM2 versions, and not for migrating data from PMM1 to PMM2. Restoring data from PMM1 to PMM2 is NOT supported since there were many architectural changes. I...
byCarlos Tutte|Jun 3, 2020|MySQL,Security
In systems nowadays, improving security is a must! One of the weakest links in the security system is the user password from where an attacker can enter. In order to improve password strength and security, MySQL provides a plugin called “Validation plugin”...
byCarlos Tutte|Mar 26, 2020|Insight for DBAs,MySQL,Percona Software
Disclaimer: The following blog post does not try to provide a solution for split-brain situations, and the example provided is for demonstrative purposes only. Inconsistencies resulting from a split-brain scenario might possibly be more complex than the one shown, so...
byCarlos Tutte|Dec 26, 2019|MySQL,Storage Engine
One of our support customers approached us with the following problem the other day: Shell mysql> CREATE TABLE child_table ( `id` int unsigned auto_increment, `column1` varchar(64) NOT NULL, parent_id int unsigned NOT NULL, PRIMARY KEY (`id`), CONSTRAINT FOREIGN...
byCarlos Tutte|Jul 5, 2019|MySQL
During our work in support, we see this again and again: “I try to connect to MySQL and am getting a 1045 error”, and most times it comes accompanied with “…but I am sure my user and password are OK”. So we decided it was worth...
