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Displaying posts with tag: mysql troubleshooting (reset)
What To Do When MySQL Runs Out of Memory: Troubleshooting Guide

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 …
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Webinar Weds 6/13: Performance Analysis and Troubleshooting Methodologies for Databases

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).

Register Now

 

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 …

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Troubleshooting MySQL Concurrency Issues with Load Testing Tools Webinar: Q & A

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, …

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Webinar Wed, 5/23: Troubleshooting MySQL Concurrency Issues with Load Testing Tools

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).

Register Now

 

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 …

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error: Failed dependencies: pkgconfig(openssl) is needed by mysql-commercial-devel-8.0.11-1.1.el7.x86_64

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, …
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MySQL 8.0 : Improved error logging

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 …

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Webinar Thursday March 1, 2018: Performance Schema for MySQL Troubleshooting

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).

Register Now

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 …

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Troubleshooting MySQL Crashes related to Metadata Locking

I just wrote an article about “Troubleshooting ‘Waiting for table metadata lock’ Errors for both MyISAM and InnoDB Tables” and then ran into a new, different metadata locking issue right after I posted it, and so I thought I’d share that too, just in case anyone ever encounters a similar situation.

In this case, mysqld kept crashing on restart, reporting “out of memory” errors:

/opt/app/mysql/product/mysql/bin//mysqld: Out of memory (Needed 840 bytes)
stack_bottom = 7fb4ebaeae58 thread_stack 0x40000
mysqld: /mysql/mysys/my_new.cc:52: int __cxa_pure_virtual():
  Assertion `! "Aborted: pure virtual method called."' failed.
mysqld: /mysql/mysys/my_new.cc:52: int __cxa_pure_virtual():
  Assertion `! "Aborted: pure virtual method called."' failed.
Fatal signal 6 while backtracing

There is a …

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Tracking down strange “Can’t find file” (ER_FILE_NOT_FOUND) Errors

Ever see an error like this in your console or error log, respectively, and wonder where it originated from?

Console (5.5.30):

ERROR 1017 (HY000): Can't find file:
'.\test\select@0020@002a@0020from@0020t1.frm' (errno: 22)

Error Log (5.5.30):

130307 23:22:04 [ERROR] C:\Program Files\MySQL\MySQL Server 5.5\bin\mysqld: 
Can't find file: '.\test\select@0020@002a@0020from@0020t1.frm' (errno: 22)

(Fwiw, they are harmless, unless it is indicative of some sql injection – but you may want to sanitize your data better, unless it’s just a one-time user error. Also, if you’re seeing it from the command line, then you’ll likely realize what you did immediately, and thus no need to ‘figure out’ what happened. However, when you *only* see this entry in the error log, and you want to know how that happened after the fact, then this is more relevant.)

At any rate, after searching the code, one can …

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New MySQL Troubleshooting Book

I was searching around and was pleasantly surprised when I ran across this new MySQL Troubleshooting book by Sveta Smirnova:

“MySQL Troubleshooting – What To Do When Queries Don’t Work”

http://shop.oreilly.com/product/0636920021964.do

Having worked with Sveta in Support for years, I’m certain this book is chock-full of great troubleshooting techniques and advices (and you can get a good idea from the “Table of Contents” listed on the above page).

I’m always happy to see new MySQL-related books.

Congratulations, Sveta!

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