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Displaying posts with tag: troubleshooting (reset)
MySQL Replication Troubleshooting: Q & A

In this blog, I will provide answers to the Q & A for the MySQL Replication Troubleshooting webinar.

First, I want to thank everybody for attending the August 25 webinar. The recording and slides for the webinar are available here. Below is the list of your questions that I wasn’t able to answer during the webinar, with responses:

Q: Hi Sveta. One question: how is it possible to get N previous events using the SHOW BINLOG EVENTS command? For example, the position is 999 and I want to analyze the previous five events. Is it possible?

A: Not, there is no such option. You cannot get the previous five events using

SHOW BINLOG EVENTS

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InnoDB Troubleshooting: Q & A

In this blog, I will provide answers to the Q & A for the InnoDB Troubleshooting webinar.

First, I want to thank everybody for attending the August 11 webinar. The recording and slides for the webinar are available here. Below is the list of your questions that I wasn’t able to answer during the webinar, with responses:

Q: What’s a good speed for buffer pool speed/size for maximum query performance?

A: I am sorry, I don’t quite understand the question. InnoDB buffer pool is an in-memory buffer. In an ideal case, your whole active dataset (rows that are accessed by application regularly) should be in the buffer pool. There is a good …

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Webinar Thursday May 26: Troubleshooting MySQL hardware resource usage

Join Sveta on Thursday, May 26, 2016, at 10 am PDT (UTC-7) for her webinar Troubleshooting MySQL hardware resource usage.

MySQL does not just run on its own. It stores data on disk, and stores data and temporarily results in memory. It uses CPU resources to perform operations, and a network to communicate with its clients.

In this webinar, we’ll discuss common resource usage issues, how they affect MySQL Server performance, and methods to find out how resources are being used. We will employ both OS-level tools, and new features in Performance Schema that provide detailed information on what exactly is happening inside MySQL Server.

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Introduction to Troubleshooting Performance – Troubleshooting Slow Queries webinar: Q & A

In this blog, I will provide answers to the Q & A for the Troubleshooting Slow Queries webinar.

First, I want to thank you for attending the April 28 webinar. The recording and slides for the webinar are available here. Below is the list of your questions that I wasn’t able to answer during the webinar, with responses:

Q: I’ve heard that is a bad idea to use

select *

; what do you recommend?

A: When I used

SELECT *

 in my slides, I wanted to underline the idea that sometimes you need to select all columns …

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Webinar Q & A for Introduction to Troubleshooting Performance: What Affects Query Execution?

In this blog, I will provide answers to the Webinar Q & A for Introduction to Troubleshooting Performance: What Affects Query Execution?

First, I want to thank you for attending the April, 7 webinar. This webinar is the third in the “MySQL Troubleshooting” webinar series and last introductory webinar in the series. The recording and slides for the webinar are available here. Here is the list of your questions that I wasn’t able to answer during the webinar, with responses:

Q: If we had some MyISAM tables, could we use …

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Troubleshooting MySQL Performance. Step Zero: Check If You Have a Performance Problem to Troubleshoot

I lost count of the number of times I had customers come to me for a regular MySQL performance check-up saying “no, we don’t have any performance problems right now”, just to find they do actually have them, they’re just not aware of it. It’s no big surprise this happens when you’re not using your system as actively as your users are.

So let me share with you one trick I’m using to quickly check if the system I’m on has any problems that need troubleshooting. Actually, it’s dead simple. And no, it’s not a slow query log, it’s Threads_running. Let me show you.

Wait, what’s wrong with the slow query log?

Nothing at all. MySQL’s slow query log is a great tool when you’re looking for slow queries. Or when you’re fishing for things to optimize – either to reduce the resource consumption, or to increase speed for queries you didn’t know are slow.

And it’s …

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MySQL 5.7.6 is out. Be prepared for big changes



Today Oracle released MySQL 5.7.6 milestone 16. With this, MySQL 5.7 has been in development for over 2 years.
Compared to MySQL 5.6, the changes are quite extensive. The main effort of the team has been focused on speed, with performance reportedly improved from 2 to 3 times compared to previous releases.
A full list of what is new would take too much space here, but I would like to mention some key points:


  • Oracle has spent a considerable amount of energy in the improvement of MySQL security and safety. You will see many new features, but even more old features that were deprecated and more that were removed after deprecation in 5.6.
  • The installation process has been changing in every …
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Introducing ‘MySQL 101,’ a 2-day intensive educational track at Percona Live this April 15-16

Talking with Percona Live attendees last year I heard a couple of common themes. First, people told me that there is a lot of great advanced content at Percona Live but there is not much for people just starting to learn the ropes with MySQL. Second, they would like us to find a way to make such basic content less expensive.

I’m pleased to say we’re able to accommodate both of these wishes this year at Percona Live! We have created a two-day intensive track called “MySQL 101” that runs April 15-16. MySQL 101 is designed for developers, system administrators and DBAs familiar with other databases but not with MySQL. And of course it’s ideal for anyone else who would like to expand their professional experience to include MySQL. The sessions are designed to lay a solid foundation on many aspects of MySQL development, design and …

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Memory summary tables in Performance Schema in MySQL 5.7

One of great innovation in MySQL 5.7 is memory summary tables в Performance Schema and corresponding views in sys schema

And as troubleshooting freak I have huge reason to greet this feature.

Before version 5.7 we had very limited abilities to diagnose memory issues in MySQL. We could use operating system tools, such as vmstat, top, free, but they only showed what MySQL server uses memory, but do not show how. In version 5.7 things changed.

Lets examine what can we study about memory usage by MySQL Server.

At first, this is total amount of memory, used by all internal MySQL structures:

mysql> select * from …

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Tweaking MySQL Galera Cluster to handle large databases - open_files_limit

September 18, 2014 By Severalnines

Galera Cluster is a popular choice for achieving high availability using synchronous replication. Though if you are planning to run huge sites with many DB objects (tables), a few tweaks are necessary. 

 

Yes, you might have been successful in loading your 1000s of databases and 1000s of tables, but what happens if you have a node failure and Galera recovery fails?

 

In this blog post we will show you how to determine one common error related to the open_files_limit that MySQL imposes, and also to spot another potential pitfall.

 

Open_files_limit

 

If you are using wsrep_sst_method=xtrabackup or wsrep_sst_method=xtrabackup-v2 then you will find a log file in the data directory of the donor node. This log file is called innobackup.backup.log.

140912 19:10:15  innobackupex: Done. …
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