MySQL configuration variables are a set of server system variables used to configure the operation and behavior of the server. In this blog post, we will explain the differences in managing the configuration variables between MySQL 5.7 and MySQL 8.0. We will explain three different ways for setting the configuration variables based on your use-case. […]
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MySQL Server generates several logs that can help you monitor the activities of the server. However, once these logs are enabled, they can grow in size and start taking up too much disk space. This is why it’s important to have an automated way of archiving and preserving MySQL log files for a certain duration, as well as deleting the old ones. In this blog post, we describe some best practices for setting up and managing MySQL error logs, general logs and slow query logs for your MySQL deployments.
Setting Up MySQL Server Logging
Let’s look at how to setup the following 3 types of logs:
Logs all the problems encountered during starting, running, or stopping mysqld. This log can be enabled by having the following option in /etc/my.cnf file:
In this blog post, we review some of the important aspects of configuring and managing SSL in MySQL hosting. These would include the default configuration, disabling SSL, and enabling and enforcing SSL on a MySQL server. Our observations are based on the community version of MySQL 5.7.21.
Default SSL Configuration in MySQL
By default, MySQL server always installs and enables SSL configuration. However, it is not enforced that clients connect using SSL. Clients can choose to connect with or without SSL as the server allows both types of connections. Let’s see how to verify this default behavior of MySQL server.
When SSL is installed and enabled on MySQL server by default, we will typically see the following:
- Presence of *.pem files in the MySQL data directory. These are the various client and server certificates and keys that are in …
Many of you have probably already heard about the new vulnerability affecting most existing MySQL forks and versions. The bug has been patched in some of the most recent MySQL and Percona Server releases and so, at least in theory, all it takes to apply a fix is to update the MySQL or Percona Server packages to their latest versions. However, it would likely require a database restart and restarts are never particularly convenient, especially when done in a rush. But this time it is actually possible to fix the vulnerability without having to upgrade and restart your MySQL instances immediately.
The attack relies on the ability to load a forged memory
allocator library through
--malloc-lib option in one
of the MySQL start-up scripts. This can only happen if such
library is first uploaded to server …
After many months of heavy development and testing, Debian 8 (Jesse) and Ubuntu 15.04 (Vivid Vervet) were released recently.
For those who already upgraded their systems and/or plan do do it in close future, we prepared builds of WebScaleSQL :-)
You can also install it using PSCE repository.
In MySQL Character encoding – part 1 we stated that the myriad of ways in which character encoding can be controlled can lead to many situations where your data may not be available as expected.
UTF8 was designed on a placemat in a New Jersey diner one night in September or so 1992.
Setting MySQL Client and Server Character encoding.
Lets restart MySQL with the correct setting for our purpose, UTF8. Here we can see the setting in the MySQL configuration file, in this case /etc/mysql/my.cnf.
character-set-server = utf8
This change is then reflected in the session and global variables once the instance is restarted with the new configuration parameter.
mysql> SELECT …[Read more]
Breaking and unbreaking your data
Recently at FOSDEM, Maciej presented “Breaking and unbreaking your data”, a presentation about the potential problems you can incur regarding character encoding whilst working with MySQL. In short, there are a myriad of places where character encoding can be controlled, which gives ample opportunity for the system to break and for text to become unrecoverable.
The slides from the presentation are available on slideshare.
Character Encoding – MySQL DevRoom – FOSDEM 2015 from …[Read more]
Driven by popularity of previous post about Debian/Ubuntu builds of WebScaleSQL and long discussions during FOSDEM conference this weekend, PSCE engineering team decided to put even more effort into.
We would like to introduce:
- RPM packages available for download
- RedHat/CentOS repository
- x86 (32-bit)
- x86_64 (64-bit)
Please note that “WebScaleSQL does not currently maintain compatibility for anything except GNU/Linux x86_64.” (WebScaleSQL FAQ)”
- CentOS 6
- CentOS 7
Packages can be downloaded from …[Read more]
Qualys announced they had found an exploit in one of the Linux core libraries – glibc – using a buffer overflow technique in gethostbyname(). They have developed a proof-of-concept in which simply sending a specially created e-mail to a mail server enabled them to create a remote shell to the Linux machine. According to Qualys, “This bypasses all existing protections (like ASLR, PIE and NX) on both 32-bit and 64-bit systems.”. How does it affect MySQL servers? Read on!
The vulnerable library call provides DNS name resolution and although it’s been obsoleted in favour of other calls, it is still widely used by both legacy and modern applications.
Having a quick search, MySQL does not seem to rely on gethostbyname() almost at all. A few uses can be found in MySQL Cluster code (NDB), …[Read more]
On a recent consulting engagement, the PSCE team were charged with what can be considered a fairly common task of synchronising tables between master and slave in MySQL Replication. On this occasion the schema contained both foreign key constraints and triggers, this post describes how we avoided the potential problems related to such an operation.
The process to synchronise tables in MySQL is to first identify the differences between tables and then execute queries which bring those tables into a consistent state. The first part of the process can be handled by the pt-table-checksum tool, which steps through the table analysing sets of rows (chunks) and recording a checksum value. Then taking advantage of replication, the same process occurs on each of the slaves and the checksums can then be compared. Once the entire table has been processed, a second tool pt-table-sync can be used …[Read more]
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