In this blog I will provide answers to the questions and queries that some of you have raised during the webinar on Nov 17th.

I would like to say thank you to all of the audience who attended the talk on November 17, 2016. You can also check the recording and slides here.

Q. How is storage distribution done across the node?

A. Each node has independent storage and other resources. There is no sharing of resource. Only the write-sets are replicated.

Q. If write-set propagation fails in some manner is there any retry mechanism?

A. write-set are written to …

As you probably know MySQL is an Open Source product licensed under the GPL v2. The GPL grants you the right to not just read and understand the code of the product but also to use, modify AND redistribute the code as long as you follow the GPL rules.

This redistribution has happened in the past various times. But in the western hemisphere only 3 of these branches/forks of MySQL are of relevance for the majority of the MySQL users: Galera Cluster for MySQL, MariaDB (Server and Galera Cluster) and Percona Server (and XtraDB Cluster).

Now it happened …

MySQL continues to be one of the most popular databases used in cloud-native applications. In fact, MySQL is so popular that other cloud databases such as AWS Aurora maintain wire protocol compatibility with MySQL. For SREs and DevOps engineers running MySQL database in production, it is crucial to understand how to monitor MySQL. MySQL poor health can lead to cascading effects on other application components. For example, slow queries can impact page load times for an application, or missing indexes can result in high-latency and application time-outs. By effectively monitoring the performance of databases and query executions, SREs and DevOps can identify if there are bottlenecks in the database tier which affect the overall application performance. With this appreciation for the importance of MySQL monitoring, let us quickly survey what techniques are commonly used for MySQL monitoring and then discuss …

After MySQL version upgrade, there is a possibility that application will start getting error/exception for INSERT/UPDATE operation due missing default data/values as follows,

ERROR:  Field ‘column_name’ doesn’t have a default value

Also above error will trigger for the wrong data type or out of range value for the column with INSERT/UPDATE sql operation.

Reason for this error is new SQL_MODE default values (MySQL 5.7 ) that included STRICT_TRANS_TABLES value in it and sql_mode value in default my.cnf created after installation[ Under /etc/my.cnf or /usr/my.cnf ]

Using Vault with MySQL

In my previous post I discussed using GPG to secure your database credentials. This relies on a local copy of your MySQL client config, but what if you want to keep the credentials stored safely along with other super secret information? Sure, GPG could still be used, but there must be an easier way to do this.

This post will look at a way to use Vault to store your credentials in a central location and use them to access your database. For those of you that have not yet come across Vault, it is a great way to manage your secrets – securing, storing and tightly controlling access. It has the added benefits of being able to handle leasing, key revocation, key rolling and auditing.

During this blog post we’ll accomplish the following …

Some days ago we found very interesting bug report with my friend: http://bugs.mysql.com/bug.php?id=71879

Problem is that, if a client moves binlog files to the other folder, stops MySQL server, update in the config file bin_log and bin_log_index values for a new path and starts server again, then the result of SHOW BINARY LOG command will be wrong:

mysql> show binary logs;
+-------------------------+-----------+
| Log_name                | File_size |
+-------------------------+-----------+
| cluster-repo-bin.000001 |       120 |
| cluster-repo-bin.000002 |         0 |
| cluster-repo-bin.000003 |         0 |
| cluster-repo-bin.000004 |         0 |
| cluster-repo-bin.000005 |         0 |
| cluster-repo-bin.000006 |       120 |
+-------------------------+-----------+

As you see, the size of some binlog files are zero. So why?

If you …

This blog post was motivated by an internal discussion about how to fully disable query cache in MySQL.

According to the manual, we should be able to disable “Query Cache” on the fly by changing

query_cache_type

 to 0, but as we will show this is not fully true. This blog will show you how to properly disable “query cache,” and how common practices might not be as good as we think.

Can we just disable it by changing variables, or does it requires a restart to avoid the global mutex? Let’s see how it works.

Some Query Cache context

The query cache stores the text of a “Select” statement together with the corresponding result that was sent to the client. If an identical statement is received later, the server retrieves the results …

Hi dear MySQL Community.
I have reported a bunch of bugs and wrote some articles, but today is a special for me
Because today I send my first PR for MySQL source code.

So I have logged a bug -> #76852 and now fixed it after year.
Okey, I know I am lazy.

Let’s reproduce the bug.
Simulating full disk condition is easy as:

mkdir /filesystems
dd if=/dev/zero of=/filesystems/tmp_fs bs=1024 count=0 seek=$[1024*10]
mkfs.ext4 /filesystems/tmp_fs
mkdir small_mounted_dir
mount -o loop /filesystems/tmp_fs /home/sh/small_mounted_dir/

Then obtain MySQL source and compile it with DEBUG. If you don’t know how to do it just refer to -> installing-mysql-from-source-cmake-issues

From now you can use MySQL Sandbox to …

This post discusses ways of fixing broken GTID replication.

This blog series is all about the daily stories we have in Managed Services, dealing with customers’ environments (mostly when we need to quickly restore a service level within the SLA time).

One of the issues we encounter daily is replication using the GTID protocol. While there are a lot of blogs written about this subject, I would like to just highlight GTID replication operations, and the way you can deal with broken replication.

Most of the time we face way more complex scenarios then the one I’m about to present as an example, but the main goal of this blog is to quickly highlight the tools that can be used to fix issues to resume replication.

After reading this blog, you might ask yourself “Now, we …

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 …