Please join Sveta Smirnova, Percona’s Principal Technical Services Engineer, as she presents Troubleshooting MySQL Access Privileges Issues on
February 23, 2017 at 11:00 am PST / 2:00 pm EST (UTC-8).

Do you have registered users who can’t connect to the MySQL server? Strangers modifying data to which they shouldn’t have access?

MySQL supports a rich set of user privilege options and allows you to fine tune access to every object in the server. The latest versions support authentication plugins that help to create more access patterns.

However, finding errors in …

In this blog post, we’ll look at a workaround for MySQL bug 72804.

Recently I worked on a ticket where a customer performed a point-in-time recovery PITR using a large set of binary logs. Normally we handle this by applying the last backup, then re-applying all binary logs created since the last backup. In the middle of the procedure, their new server crashed. We identified the binary log position and tried to restart the PITR from there. However, using the option

--start-position

, the restore failed with the error “The BINLOG statement of type Table_map was not preceded by a format description BINLOG statement.” This is a known bug and is reported as MySQL …

This post introduces PyMyTools v0.1: my first version of a simple diagnostic toolkit for automating boring DBA tasks. Read on for tool descriptions and demonstrations!

Introduction No lengthy introductions this time:

• I wrote these tools to make my own everyday tasks less time consuming. I hope you too will find them useful.
• Tools can be downloaded from GitHub and are provided under the MIT License.
• Your feedback is very welcome (use GitHub Issues).

Tools: general description The tools are designed to automate some of the simple DBA tasks:

• Monitor the values of server status variables.
• Report on basic status variables (buffer/cache usage, uptime, query traffic).
• Dump …

In this blog we are going to share my recent experience with an issue which we faced during migration between two Ubuntu servers.

The activity was pretty simple, the client had bought a new machine with enhanced memory and faster disk, so the data has to be transferred to the new server and live MySQL replication has to be configured between the old and the new server.

For the hot and live data transfer we used xtrabackup’s stream method, the data transfer happened smoothly without any issue.

Everything was set and we had applied the log and followed the normal procedure to change the ownership of datadir to “mysql” and all the entries in the my.cnf were double checked.

When we intended to start mysql, the service didn’t come up instead we had a weird error as below.

MySQL Error:
——————

2016-08-31 22:35:27 9938 [ERROR] InnoDB: ./ibdata1 can't be opened in …

I'm not a huge fan of the InnoDB FULLTEXT feature and I admit I wasn't too keen to play with it in the past. Apparently, the feeling is mutual and so FULLTEXT issues haven't popped up in too many projects I worked on... until last week.

This post describes the troubleshooting process of a FULLTEXT cache performance issue. Quite inconspicuous at the beginning, it proved to be a lot of fun in the end.

Ready, Set, GDB!
Background It all started with a generic performance issue report unrelated to FULLTEXT indexing. The issue, as described in the report, was:

1. The server performs acceptably for a few days.
2. After a certain amount of time, DML performance suddenly drops and remains low until the server is rebooted.
3. Reboot restores original performance, which again only lasts for a few days.

The situation was resulting in DML latency degradation during normal OLTP …

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

. …

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 …

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.

…

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 from …

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 …