The latest from the MySQL community

So you talk to a database, doing transactions. What happens actually, behind the scenes? Let’s have a look.

There is a test table and we write data into it inside a transaction:

CREATE TABLE t (
  id serial,
  data varbinary(255)
)

START TRANSACTION READ WRITE
INSERT INTO t ( id, data ) VALUES (NULL, RANDOM_BYTES(255))
COMMIT

The MySQL test instance we are talking to is running on a Linux machine, and otherwise idle to make observation easier. Also, we configured it with innodb_use_native_aio = false because observing actual physical asynchronous I/O and attributing it to the statement that caused it is really hard.

Setting things up this way, we can use lsof and strace to see things. But before we do this, let’s set some expectations and establish some background knowledge.

The Log/Data Memory/Storage quadrants

Upper half: Log structures, Lower half: Data …

On July 21, 2020, Percona delivered an updated version of our Percona Kubernetes Operator for Percona XtraDB Cluster (PXC) focused on easing deployment and operations management of a clustered MySQL environment. Included in the Percona Distribution for MySQL, our Operator is based on the best practices for MySQL cluster configuration and setup in Kubernetes. This update adds a variety of important new features including:

Smart Update to Safely and Reliably Upgrade your PXC Environment Automatically
We implemented a new update strategy called Smart Update. Smart Update is aware of the context of your environment and minimizes the number of failover events that need to occur to fully upgrade a …

Dear MySQL users,

MySQL Shell 8.0.21 is a maintenance release of MySQL Shell 8.0 Series (a
component of the MySQL Server). The MySQL Shell is provided under
Oracle’s dual-license.

MySQL Shell 8.0 is highly recommended for use with MySQL Server 8.0 and
5.7. Please upgrade to MySQL Shell 8.0.21.

MySQL Shell is an interactive JavaScript, Python and SQL console
interface, supporting development and administration for the MySQL
Server. It provides APIs implemented in JavaScript and Python that
enable you to work with MySQL InnoDB cluster and use MySQL as a document
store.

The AdminAPI enables you to work with MySQL InnoDB cluster and InnoDB
ReplicaSet, providing integrated solutions for high availability and scalability
using InnoDB based MySQL databases, without requiring advanced MySQL
expertise.  For more …

Dear MySQL users,

MySQL Shell 8.0.20 is a maintenance release of MySQL Shell 8.0 Series (a
component of the MySQL Server). The MySQL Shell is provided under
Oracle’s dual-license.

MySQL Shell 8.0 is highly recommended for use with MySQL Server 8.0 and
5.7. Please upgrade to MySQL Shell 8.0.20.

MySQL Shell is an interactive JavaScript, Python and SQL console
interface, supporting development and administration for the MySQL
Server. It provides APIs implemented in JavaScript and Python that
enable you to work with MySQL InnoDB cluster and use MySQL as a document
store.

The AdminAPI enables you to work with MySQL InnoDB cluster and InnoDB
ReplicaSet, providing integrated solutions for high availability and scalability
using InnoDB based MySQL databases, without requiring advanced MySQL
expertise.  For more …

Dear MySQL users,

MySQL Connector/Node.js is a new Node.js driver for use with the X
DevAPI. This release, v8.0.21, is a maintenance release of the
MySQL Connector/Node.js 8.0 series.

The X DevAPI enables application developers to write code that combines
the strengths of the relational and document models using a modern,
NoSQL-like syntax that does not assume previous experience writing
traditional SQL.

MySQL Connector/Node.js can be downloaded through npm (see
https://www.npmjs.com/package/@mysql/xdevapi for details) or from
https://dev.mysql.com/downloads/connector/nodejs/.

To learn more about how to write applications using the X DevAPI, see
…

In my day to day tasks as a DB Engineer at Mydbops we have been using multiple MySQL tools for multiple use cases to ensure an optimal performance and availability for servers managed by our Remote DBA Team.

A tool like pt-online-schema can be used for any DDL changes ( Overview to DDL algorithm ), if any tool which needs to scheduled for longer period we tend to use screen or cron.

Some of the problems we face when we demonise the process or use screen for running processes.

• The daemon process gets killed when the server reboot happens. …

ProxySQL Firewall Overview

ProxySQL’s flexible query rules engine has many uses, from Read/Write splitting, sharding and even creating firewall blacklist. This allows ProxySQL to be loved by both Performance and Security-minded engineers.

Starting in ProxySQL 2.0.9, ProxySQL has another Security feature: the Firewall Whitelist.

Modeled on MySQL Enterprise Firewall, this allows a security-conscious administrator to tune access to only allow certain queries.

Imagine a situation where your webapp gets hacked, which exposes your user’s database credentials.

If your webapp connects directly to the database, the malicious user can do what they want to your data with the same permissions your webapp has.

So perhaps they can’t just DROP TABLE because you’ve smartly removed DDL permissions …

Ever wanted to extend MySQL and add some feature you think it is missing?  With MySQL plugins, you can do exactly that.  One thing that has bothered me for several years is that you cannot easily retrieve system metrics from within MySQL.  Whether I am connecting via a remote connection or looking to add features to monitoring without the need for another interface with the server, I have wanted to retrieve system metrics without leaving the MySQL interface.

So, I started a Proof of Concept for this.  My goal was to get metrics such as RAM (total, used, free), system load, CPU utilization, disk utilization for the file system containing the datadir, and more.  My objective was to do this as efficiently within MySQL as possible.  For this, I chose to utilize standard C libraries in as few lines of code as possible without having to scrape system files or run commands to get the data.  The …

Have you ever had to type out a massive CREATE TABLE statement by hand? One with dozens of columns? Maybe several dozens of columns? There are likely some GUI tools to help with large CREATE TABLE commands. Or, other drag-n-drop types of software that I am not familiar with. What if you could write a few lines of Python code and take care of a huge CREATE TABLE statement with way less effort than typed manually? Interested? Continue reading and see how using pandas, pyodbc, and MySQL…

Photo by Vorsen Furniture on Unsplash

OS, Software, and DB used:

• OpenSuse Leap 15.1
…

Why another article on this, Marco?

MySQL deadlocks is a topic covered many times, including here at Percona. I suggest you review the reference section at the end of this post for articles on how to identify deadlocks and from where they are generated.

So why another article?

The answer is that messages we receive like the following are still very common:

User (John): “Marco, our MySQL is having problems”
Marco: “Ok John what problems? Can you be a bit more specific?”
John: “Our log scraper is collecting that MySQL has a lot of errors”
Marco: “Ok can you share the MySQL log so I can review it?”
John: “Errors are in the application log, will share one application log”

Marco reviews the log and in it he finds:

“ERROR 1213 (40001): Deadlock found when trying to get lock;
try restarting transaction”

Marco’s reaction is: “Oh …