Database architecture and design are becoming an increasingly lost art. With new technologies and the push towards faster development cycles, people continue to take shortcuts, often to the detriment of long-term performance, scalability, and security. Designing how your application stores, accesses, and processes data is so fundamentally important, it can not be overlooked. I want people to understand that early design choices can have a profound impact on their applications. To that end, I will be exploring database design principles and practices over the next several months. I am starting with every developer’s favorite data format: JSON!

It seems that almost every database over the last few years has introduced various degrees of support for storing and interacting with JSON objects directly. While these features are designed to make it easier for application developers to write code faster, the implementations of each implementation …

The Problem

State Snapshot Transfer can be a very long and expensive process, depending on the size of your Percona XtraDB Cluster (PXC)/Galera cluster, as well as network and disk bandwidth. There are situations where it is needed though, like after long enough node separation, where the gcache on other members was too small to keep all the needed transactions.

Let’s see how we can avoid SST, yet recover fast and without even the need for doing a full backup from another node.

Below, I will present a simple scenario, where one of the cluster nodes was having a broken network for long enough that it will make …

Problem Statement

Having backups of binary logs is fairly normal these days. The more recent binary logs are copied offsite, the better RPO (Recovery Point Objective) can be achieved. I was asked multiple times recently if something could be done to “stream” the binary logs to S3 as close to real-time as possible. Unfortunately, there is no readily available solution that would do that. Here, I show what can be done and also show a proof of concept implementation, which is not suitable for production use.

In this example, the instance has two binary log files (mysql-bin.000001 and mysql-bin.000002) already closed and mysql-bin.000003 being written. A trivial solution for backing up these binary log files would be to back up just the closed ones (the one that is not written). The default size of the binary log file is 1 GB. This means with this solution we would have a 1 GB binlog not backed up in the worst-case scenario. On …

As some of you likely know, I have a favorable view of ZFS and especially of MySQL on ZFS. As I published a few years ago, the argument for ZFS was less about performance than its useful features like data compression and snapshots. At the time, ZFS was significantly slower than xfs and ext4 except when the L2ARC was used.

Since then, however, ZFS on Linux has progressed a lot and I also learned how to better tune it. Also, I found out the sysbench benchmark I used at the time was not a fair choice since the dataset it generates compresses much less than a realistic one. For all these reasons, I believe that it is time to revisit the performance aspect of MySQL on ZFS.

ZFS Evolution

In 2018, I reported ZFS performance results based on version 0.6.5.6, the default version available in Ubuntu Xenial. The present post is using …

“It would be nice to have an option, that would allow to suppress the DEFINER statement in the CREATE VIEW statements generated by mysqldump. This would help when transferring data structures between databases with different security models.” 

TLDR;

Use mysqlpump with option

--skip-definer

instead of

mysqldump

. The Story

This was requested as MySQL Bug #24680 on Nov 29, 2006. This feature request got large Community support. Even if we cannot see the number of people who voted for this request, the number of comments is impressive.

The request is very reasonable:

mysqldump

is widely used during application development and it is a very common practice to migrate database structure …

The new MyDumper 0.10.7 version, which includes many new features and bug fixes, is now available.  You can download the code from here.

For this release, we have added several features like WHERE support that is required for partial backups. We also added CHECKSUM for tables which help to speed up the restore of large tables to take advantage of fast index creation, and more.

New Features:

• Adding metadata file per table that contains the number of rows #353
• Adding –where support #347 …

One of the new features introduced in MySQL 8.0.24 was the ability to log all SQL statements that are issued in the MySQL Shell to the system log. This is a useful feature that can greatly assist in tracking who did what on the system.

Usage

The simplest way to utilize the new Shell logging feature is to simply start the MySQL Shell with the syslog option enabled like so:

$> mysqlsh --syslog --sql root@localhost

From this point forward all SQL entered in the MySQL Shell will be logged to the system log. For example, the following SQL is entered into the Shell:

MySQL  localhost:33060+ ssl  SQL > show databases;

+--------------------+
| Database           |
+--------------------+
| information_schema |
| mysql              |
| performance_schema |
| sys                |
+--------------------+

We can now check the system log and verify that the statement above was indeed logged …

MySQL 8 brought many highly anticipated features, with support for user roles, a new shell, a more robust data dictionary, and better SQL support, just to name a few. There are lesser-known new features, however, that aim to reduce overall DBA workload and streamline management processes – and one of these is support for dual passwords, first implemented in MySQL 8.0.14. User accounts are now permitted to have dual passwords, with a designated primary and secondary. This makes it possible to seamlessly perform user credential changes even with a large number of servers, or with multiple applications connecting to different MySQL servers.

Historically, a MySQL credential change had to be timed so that when the password change was made and propagated throughout the database nodes, all applications that use that account for connections had to be updated at the same time. This is problematic for many reasons, but with database and application …

Some of you may use MySQL’s asynchronous replication feature called Semisynchronous Replication (aka semi-sync), and now with the MySQL Semi-Sync Summary Dashboard + Percona Monitoring and Management (PMM), you can see the most important metrics! Refer to the Install & Usage steps for deployment details (note you need Replication Set defined!).

What is Semisynchronous Replication

When enabled, Semisynchronous Replication instructs the Primary to wait until at least one replica has received and logged the event to the replica’s local relay log before completing the COMMIT on a transaction. This provides a higher level of data integrity because now it is known that the data exists in two places. This feature ensures a balance …

Don’t Try This at Home!

Disclaimer: The procedure described in this blog post is not officially supported by Percona XtraBackup. Use it under your responsibility. I tested and used it successfully, but your mileage may vary.

Note from the author: Wikipedia defines clickbait as text (or a link) that is designed to attract attention and to entice users to read that online content, with a defining characteristic of being deceptive. Maybe the headline of this post is a bit deceptive, as there is no Percona XtraBackup for Windows, but I hope you will not feel deceived after reading this blog post, I just felt that it was funny to use a clickbait-style while writing it.

He Couldn’t Believe it When He Read That Post!

Pep had to migrate a client database from Windows to Linux …