UPDATE: I should clarify. This ticket is an internal ticket at DealNews. It is about what the defaults on our servers should be. It is not about what the defaults should be in MySQL. The frustration that UTF8 support in MySQL is only 3 bytes is quite real.

 This epic ticket of the day is brought to you by Joe Hopkinson.

#7940: Default charset should be utf8mb4
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 The RFC for UTF-8 states, AND I QUOTE:

 > In UTF-8, characters from the U+0000..U+10FFFF range (the UTF-16
 accessible range) are encoded using sequences of 1 to 4 octets.

 What's that? You don't believe me?! Well, you can read it for yourself
 here!

…

A customer asked whether we they could have 10 or more masters consolidate all the data into a single central slave. After getting a bit more information from them and seeing the application functionality, it was clear that MySQL Labs 5.7.5 Multi Source Replication could be a good candidate. Why?:
– Each master is independent from the rest of the masters.
– One-way traffic: there is only one way to update a row, and that’s from the master.
– All the masters use the same schema and table, but no single master will ever need to, nor be able to update a row from another master.
– PK determined via app & master env.

Multisource replication is still in http://labs.mysql.com, but here’s what I did to test it out.

First, I read:
…

Following on the heels of last week’s update to the Java client, the MariaDB project is pleased to today announce updates to both MariaDB Connector/C and Connector/ODBC. They are both Stable (GA) releases.

See the Release Notes and Changelogs for detailed information on each of these releases and contain many bug fixes and enhancements.

Download Connector/C 2.1.0

Release Notes Changelog

About MariaDB Connector/C

…

Cloud security company Qualys announced Tuesday the issues prevalent in glibc since version 2.2 introduced in 2000-11-10 (the complete Qualys announcement may be viewed here). The vulnerability, CVE-2015-0235, has been dubbed “GHOST.”

As the announcement from Qualys indicates, it is believed that MySQL and by extension Percona Server are not affected by this issue.

Percona is in the process of conducting our own review into the issue related to the Percona Server source code – more information will be released as soon as it is available.

In the interim the current advisory is to update your glibc packages for your distributions if they are in fact vulnerable. The C code from the Qualys announcement may aid in your diagnostics, section 4 of …

This Log Buffer Edition keeps the aim high and brings few of the best blog posts from Oracle, SQL Server and MySQL.

Oracle:

3 Modes for Moving Data to the BI Applications DW from a Source Application Database.

JSON for APEX Developers.

Neelakanth Nadgir posted a useful utility that prints out various statistics about the ZFS Adaptive Replacement Cache (ARC).

Obtaining Bonus Depreciation Methods for Oracle Fixed Assets.

Existing News – …

Fri, 2015-01-23 15:14markusmakela

MaxScale’s filter system is very flexible and enables a new way of interacting with queries. The upcoming firewall filter shows just one of the many ways that you can control and manage the flow of queries through MaxScale.

The firewall filter is meant to offer finer and more varied control over queries and their execution. The main idea of the filter is to work as a base to build and improve upon and to show just how that can be done with MaxScale.

The filter provides a variety of ways to control which kinds of queries get executed. The simplest ones block queries that happen during a certain time range or do a certain operation. The more complex ones can match queries using a regular expression, check for the existence of a WHERE clause in the query or deny the query on the basis of the current session’s query speed. These rules can be applied to specific users or network ranges or …

Long running transactions can be problematic for OLTP workloads, particularly where we would expect most to be completed in less than a second. In some cases a transaction staying open just a few seconds can cause behaviour that is entirely unexpected, with the developers at a loss as to why a transaction remained open. There are a number of ways to find long running transactions, luckily versions of MySQL from 5.6 onwards provide some very insightful instrumentation.

Here we will use the information_schema coupled with the …

Oracle have just made availble the Release Candidate for MySQL Cluster 7.4 (MySQL Cluster 7.4.3) – it can be downloaded from the development release tab here. Note that this is not a GA release and so we wouldn’t recommend using it in production.

The delta between this RC and the 7.4.2 DMR can be viewed in the MySQL Cluster 7.4.3 Release Notes

There are three main focus areas for this RC and the purpose of this post is to briefly introduce them:

• Active-Active (Multi-Master) Replication
• Performance
• Operational improvements (speeding up of restarts; enhanced memory …

It is a common database pattern to increment an INT column when an event happens, such as a download. Early last year at GitHub we started encountering issues with slow UPDATES to these types of counters.

You can go far with this pattern until bursts of these types of events happen in parallel and you experience contention on a single row. When multiple transactions are trying to update the counter you are essentially forcing these transactions to run serially which is bad for concurrency.

You can see here a dramatic increase in query time when a burst like this occurred:

<img src=”/images/burst.png” height=“200px” width=”725px” />

To avoid problems like this we had to do this kind of counting differently. We decided on using a separate table with a schema similar to this:

CREATE TABLE `slotted_counters` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `record_type` int(11) NOT NULL, …

As a MySQL DBA/consultant, it is part of my job to decode the MySQL binary logs – and there are a number of reasons for doing that. In this post, I’ll explain how you can get the important information about your write workload using MySQL row-based binary logs and a simple awk script.

First, it is important to understand that row-based binary logs contain the actual changes done by a query. For example, if I run a delete query against a table, the binary log will contain the rows that were deleted. MySQL provides the mysqlbinlog utility to decode the events stored in MySQL binary logs. You can read more about mysqlbinlog in detail in the reference manual here.

The following example illustrates how mysqlbinlog displays row events that specify data modifications. These correspond to events with the WRITE_ROWS_EVENT, UPDATE_ROWS_EVENT, …