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. … [Read more...] about How to quickly patch a MySQL server against CVE-2016-6662?
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 :-) http://repo.psce.com/download/webscalesql/deb/x86_64/vivid/ http://repo.psce.com/download/webscalesql/deb/x86_64/jessie/ You can also install it using PSCE repository. … [Read more...] about WebScaleSQL builds available for Debian 8 and Ubuntu 15.04
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. … [Read more...] about MySQL Character encoding – part 2
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. … [Read more...] about MySQL Character encoding – part 1
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. … [Read more...] about WebScaleSQL RPMs available at PSCE repository
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! … [Read more...] about MySQL and the GHOST: glibc gethostbyname buffer overflow
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 to generate queries which will correct any inconsistencies, executing queries that will result in NOOP on the master, yet effect change on the slave, bringing the master and slave into sync. At the time of writing, the documentation for the current version of each tool was available here: pt-table-checksum pt-table-sync There are a number of potential issues to which may arise whilst executing these procedures, however this post just looks at tables with foreign key definitions, and secondly the existence of triggers on the tables being synchronised. Specifically … [Read more...] about Syncronizing MySQL where tables have triggers and foreign keys defined