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Showing entries 1 to 10 of 27 10 Older Entries

Displaying posts with tag: Managing MySQL (reset)

WebScaleSQL builds available for Debian 8 and Ubuntu 15.04
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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 :-)

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MySQL Character encoding – part 2
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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 …

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MySQL Character encoding – part 1
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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 …


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WebScaleSQL RPMs available at PSCE repository
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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

Architectures covered:

  • x86 (32-bit)
  • x86_64 (64-bit)

Please note that “WebScaleSQL does not …

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MySQL and the GHOST: glibc gethostbyname buffer overflow
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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 …

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Syncronizing MySQL where tables have triggers and foreign keys defined
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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 …

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Hunting for “Locked” queries with pt-stalk utility
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Recently we faced an issue when Nagios reported significant amount of “Locked” queries.
To investigate and debug the issue we needed to get more insight about the state of MySQL and the OS at the time the locks occurred.
This is how we got the much needed information:


wget http://bit.ly/1ltoZtk -O pt-stalk
chmod +x pt-stalk
mkdir -p /tmp/pt-stalk
sudo pt-stalk --daemonize --notify-by-email <EMAIL> --log /tmp/pt-stalk/pt-stalk.log --user root --dest /tmp/pt-stalk --function processlist --variable State --match Locked --threshold 20 --cycles=10 --sleep=15 --run-time=15 …





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Diagnosing problems with SQL imports
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Importing a text file containing a list of SQL commands into MySQL is a straightforward task. All you need to do is simply feed the file contents through pipe into MySQL command line client. For example: mysql app_production < dump.sql.

The reasons for doing such imports can be very different - restoring MySQL backups created with mysqldump, manually replaying binary log events or performing database migrations during software roll-outs.

While the task is simple, the import may not end successfully and when this happens, how to tell what the problem was?

MySQL errors

Whenever database hits an error, …

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Granting privileges may break replication in MySQL 5.6.10
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MySQL lets database administrators define access rights on many levels – from the ability to run global commands down to access to individual columns. Some rights can be applied to many different objects, such as for example SELECT or UPDATE, which can be granted globally or restricted only to certain databases or tables, while others are only meant for one specific purpose. An example of the latter could be FILE privilege, which permits user to interact with the file system from inside a database instance. It only makes sense as the global right and not anywhere else.

As any other activity that produces changes, GRANT …

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MySQL Security: Overview of MySQL security features
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In a world driven by computers, most companies rely on systems that are entirely built around databases. Losing data, or even as little as losing the full control over it, could bring any business down. Frequently databases hold sensitive information such as personal details, transaction statements, credit card data – among many other things. This is also why running certain types of databases is regulated in many countries by local as well as international laws – especially in Europe.

What is at stake?

  • Availability. When a database or data disappear, business stops. Assuming you have working …
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Showing entries 1 to 10 of 27 10 Older Entries

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