If you’ve encountered the “Encryption can’t find master key” error while starting MySQL, you’re likely facing issues with the keyring plugin. I recently faced a similar issue on my server,…

The post Troubleshooting MySQL: Encryption can’t find Master Key first appeared on Change Is Inevitable.

At the Percona engineering team, we often receive requests to analyze changes in MySQL/Percona Server for MySQL behavior from one version to another, either due to regression or a bug fix (when having to point out to a customer that commit X has fixed their issue and upgrading to a version including that fix will solve their problem).

In this blog post, we will analyze the approach used to fix PS-7019 – Correct query results for LEFT JOIN with GROUP BY.

Each release comes with a lot of changes. For example, the difference between MySQL 8.0.19 to 8.0.20:

git diff mysql-8.0.19..mysql-8.0.20 | wc -l
737454
git diff mysql-8.0.19..mysql-8.0.20 --name-only | wc -l
4495

737K lines in 4495 files have changed from one minor version to another.

git …

Understanding how MySQL handles connections and Troubleshooting MySQL error 1040 – Too many connections! How to interpret “MySQL error 1040 – Too many connections ! ” ?

When a client tries to log into MySQL it may sometimes be rejected and receive an error message saying that there are “too many connections“. This means that the maximum number of clients that may be connected to the server has been reached. Either the client will have to wait for another client to log off, or the administrator will have to increase the maximum number of connections allowed.

Information about connections to a server can be found using the SHOW STATUS statement:

SHOW STATUS LIKE 'max_used_connections';

Prerequisite – Few points to remember before working or troubleshooting MySQL ” Too many connections ! ” error

1. MySQL does not have it’s own thread handling mechanism / …

Troubleshooting crashes is never a fun task, especially if MySQL does not report the cause of the crash. For example, when MySQL runs out of memory. Peter Zaitsev wrote a blog post in 2012: Troubleshooting MySQL Memory Usage with a lots of useful tips. With the new versions of MySQL (5.7+) and performance_schema we have the ability to troubleshoot MySQL memory allocation much more easily.

In this blog post I will show you how to use it.

First of all, there are 3 major cases when MySQL will crash due to running out of memory:

1. MySQL tries to allocate more memory than available because we specifically told it to do so. For example: you did not set innodb_buffer_pool_size correctly. This is very easy to fix
2. There is some other process(es) on the server that allocates RAM. It can be the application …

Please join Percona’s CEO, Peter Zaitsev as he presents Performance Analysis and Troubleshooting Methodologies for Databases on Wednesday, June 13th, 2018 at 11:00 AM PDT (UTC-7) / 2:00 PM EDT (UTC-4).

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Have you heard about the USE Method (Utilization – Saturation – Errors)? RED (Rate – Errors – Duration), or Golden Signals (Latency – Traffic – Errors – Saturations)?

In this presentation, we will talk briefly about these different-but-similar “focuses”. We’ll discuss how we can apply them to data infrastructure performance analysis, troubleshooting, and monitoring.

We will use MySQL as an …

In this blog, I will provide answers to the Q & A for the Troubleshooting MySQL Concurrency Issues with Load Testing Tools webinar.

First, I want to thank everybody for attending my May 23, 2018, webinar on troubleshooting tools for MySQL. The recording and slides for the webinar are available here. Below is the list of your questions that I was unable to answer fully during the webinar.

Q: What do you recommend for benchmarking NDB cluster? Which should be used and how?

A: The issue with benchmarking NDB cluster is not the tool choice, …

Please join Percona’s Principal Support Escalation Specialist, Sveta Smirnova, as she presents Troubleshooting MySQL Concurrency Issues with Load Testing Tools on Wednesday, May 23, 2018 at 11:00 AM PDT (UTC-7) / 2:00 PM EDT (UTC-4).

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Normally, we use benchmarking tools when we are developing applications. When applications are deployed, benchmarks tests are usually too late to help.

This webinar doesn’t cover actual benchmarks, but it does look at how you can use benchmarking tools for troubleshooting. When you need to repeat a situation caused by concurrent client execution, they can be your best …

Recently we were evaluating MySQL 8 Enterprise for a customer. During our installation (our MySQL Enterprise Edition installations are always RPM based) using RPM file (CentOS Linux release 7.4.1708 (Core))  we ended up in a very unusual error, “error: Failed dependencies:pkgconfig(openssl) is needed by mysql-commercial-devel-8.0.11-1.1.el7.x86_64” , This was happening more specifically during the installation of “mysql-commercial-devel-8.0.11-1.1.el7.x86_64.rpm” . So decided to write this post about the error and how we fixed it.

[root@localhost MySQL8-Enterprise-RPM]# rpm -ivh mysql-commercial-server-8.0.11-1.1.el7.x86_64.rpm mysql-commercial-client-8.0.11-1.1.el7.x86_64.rpm mysql-commercial-libs-8.0.11-1.1.el7.x86_64.rpm mysql-commercial-common-8.0.11-1.1.el7.x86_64.rpm mysql-commercial-devel-8.0.11-1.1.el7.x86_64.rpm 
warning: mysql-commercial-server-8.0.11-1.1.el7.x86_64.rpm: Header V3 DSA/SHA1 Signature, …

We extensively use MySQL error logging for proactive diagnostics, MySQL 8 has improved error logging which is capable of sending multiple format (like JSON) logs  to multiple destinations like Kibana for log processing and analysis. Let’s see how this works:

MySQL 8.0 default configuration

mysql> select * from global_variables where VARIABLE_NAME like 'log_error_%';
+---------------------+----------------------------------------+
| VARIABLE_NAME       | VARIABLE_VALUE                         |
+---------------------+----------------------------------------+
| log_error_services  | log_filter_internal; log_sink_internal |
| log_error_verbosity | 2                                      |
+---------------------+----------------------------------------+

Now that means log events will pass first through log_filter_interval (built-in filter component) and then through log_sink_interval (built-in …

Please join Percona’s Principal Support Engineer, Sveta Smirnova, as she presents Performance Schema for MySQL Troubleshooting on Thursday, March 1, 2018, at 10:00 am PST (UTC-8) / 1:00 pm EST (UTC-5).

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Performance Schema, first introduced in version 5.5, is a really powerful tool. It is actively under development, and each new version provides even more instruments for database administrators.

Performance Schema is complicated. It is also not free: it can slow down performance if you enable certain …