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Slow query log – Confusing information in manuals

Below is the excerpt from MySQL manuals on slow query log :

“By default, administrative statements are not logged, nor are queries that do not use indexes for lookups. This behavior can be changed using log_slow_admin_statements and log_queries_not_using_indexes, as described later. “

This manual entry is kind of misleading . It means that queries not using indexes are not logged by default. Let us see what the reality is :

1) Let us see if queries not using indexes are being logged.

Below table does not have index:

mysql> describe employee ;
+-------+---------+------+-----+---------+-------+
| Field | Type    | Null | Key | Default | Extra |
+-------+---------+------+-----+---------+-------+
| ID    | int(11) | YES  |     | NULL    |       |
+-------+---------+------+-----+---------+-------+
1 row in set (0.00 sec)

mysql> show indexes from employee ;
Empty set (0.00 sec) …
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Smoke-Testing VividCortex's Agents With A Sanity Check Tool

One of our agents, vc-mysql-query, works by sniffing TCP traffic with libpcap and decoding the MySQL protocol. As you can imagine, it’s one of the most complicated portions of our codebase. It’s also difficult to test. We have a set of tests using tcpdump files of production MySQL traffic to deterministically test the sniffer code. We run the tcpdump files through the sniffer and check the generated output. The issue with this is that every time we add a new dump file, it’s a lot of manual work to know for sure what we should be seeing in the output. If the agent says that 100 SELECTs were run, how do we make sure it’s true?

In order to brute-force test and try to smoke out bugs, we wrote a small Go tool that we call the sanity-check. It runs a production version of vc-mysql-query and tests it with a black-box approach.

Functionality

The first thing that the sanity-check tool does is create a test database to hold …

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Ignoring the lost+found Directory in your Datadir

I still get asked about the lost+found directory enough, and so I wanted to provide a current update.

The lost+found directory is a filesystem directory created at the root level of a mapped drive. Thus this is common to see if you create your mysql datadir at the root level of a mapped drive.

In the past, you could ignore it, if it wasn’t too problematic for you, or you could move your datadir down a level, and then it wouldn’t be created in the datadir anymore.

However, there is now the –ignore-db-dir option. It is actually not too new (it’s been in MariaDB since 5.3.9 and 5.5.28, and in MySQL as of 5.6.3), but I don’t think many are too familiar with it.

But when you do run into this problem, some/many would prefer to add a single line to the config file rather than move the datadir.

To do this, just add the following option to your my.cnf file, under the [mysqld] section (it cannot be set …

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libAttachSQL Single Thread vs. libmysqlclient Multi Thread

I have recently posted up benchmarks of libAttachSQL vs. libmysqlclient using sysbench. Whilst these are great and shows the results I hoped for, this isn't what we designed libAttachSQL for. It was designed for non-blocking many connections per thread.

With this in mind I spent today knocking up a quick benchmark tool which replicates the Sysbench "Select" test but using libAttachSQL's connection groups on a single thread. The code for this can be seen in the new AttachBench GitHub tree. Of course the secondary reason for this is to try and hammer the connection groups feature, which of course did find a bug when I scaled to around 32 connections. This has been fixed in libAttachSQL's master ready for …

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How to close POODLE SSLv3 security flaw (CVE-2014-3566)

Padding Oracle On Downgraded Legacy Encryption

First off, the naming “convention” as of late for security issues has been terrible. The newest vulnerability (CVE­-2014-3566) is nicknamed POODLE, which at least is an acronym and as per the header above has some meaning.

The summary of this issue is that it is much the same as the earlier B.E.A.S.T (Browser Exploit Against SSL TLS), however there’s no known mitigation method in this case – other than entirely disabling SSLv3 support, in short, an attacker has a vector by which they can retrieve the plaintext form your encrypted streams.

So let’s talk mitigation, the …

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And the Bose Mobile Speaker DrupalCon prize draw winner is...

Wed, 2014-10-15 17:46robertsilen

DrupalCon Amsterdam was a great event with a lot of energy! It was good to hear so many Drupal developers have already made the switch to MariaDB including the Drupal Association!

We are happy to announce the winner of the free prize draw for the Bose SoundLink Mini:

Matthew Radcliffe at Kosada

Matthew has received his Bose SoundLink Mini and is very happy with the prize!

If you missed Maria-Luisa's talk on Wednesday about the benefits of deploying Drupal on MariaDB check out the slides on slideshare.

Want to know more about MariaDB and Drupal?

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And the Bose Mobile Speaker DrupalCon prize draw winner is...

Wed, 2014-10-15 17:46robertsilen

DrupalCon Amsterdam was a great event with a lot of energy! It was good to hear so many Drupal developers have already made the switch to MariaDB including the Drupal Association!

We are happy to announce the winner of the free prize draw for the Bose SoundLink Mini:

Matthew Radcliffe at Kosada

Matthew has received his Bose SoundLink Mini and is very happy with the prize!

If you missed Maria-Luisa's talk on Wednesday about the benefits of deploying Drupal on MariaDB check out the slides on slideshare.

Want to know more about MariaDB and Drupal?

[Read more]
Experimenting with the new Data Dictionary Labs Release

Labs releases are intended to provide early access to new features. As Gopal notes in his recent blog post About the Data Dictionary Labs Release, there is a notable restriction where upgrading from any previous MySQL database version is not supported.

Today, I thought I would demonstrate how to get the data dictionary lab up and running on a fresh Ubuntu 14.04 installation:

# Download from labs.mysql.com
wget http://downloads.mysql.com/snapshots/pb/mysql-5.7.5-labs-dd/mysql-5.7.5-labs-dd-linux-el6-x86_64.tar.gz

# extract it to /usr/local/mysql
# more or less following instructions in INSTALL-BINARY

groupadd mysql
useradd -r -g mysql mysql
 
tar -xzf mysql-5.7.5-labs-dd-linux-el6-x86_64.tar.gz
mv mysql-5.7.5-labs-dd-linux-el6-x86_64 /usr/local/
ln -s /usr/local/mysql-5.7.5-labs-dd-linux-el6-x86_64 …
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Rackspace doubling-down on open-source databases, Percona Server

Founded in 1998, Rackspace has evolved over the years to address the way customers are using data – and more specifically, databases. The San Antonio-based company is fueling the adoption of cloud computing among organizations large and small.

Today Rackspace is doubling down on open source database technologies. Why? Because that’s where the industry is heading, according to Sean Anderson, Manager of Data Services at Rackspace. The company, he said, created a separate business unit of 100+ employees focused solely on database workloads.

The key technologies under the hood include both relational databases (e.g., MySQL, Percona Server, and MariaDB) and NoSQL databases (e.g., MongoDB, Redis, and Apache Hadoop).

Last July Rackspace …

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libAttachSQL 0.9.0 RC - Connection Groups

It has been just over 4 months since I started working on libAttachSQL for HP's Advanced Technology Group. Today marks the first (and hopefully only) RC release of the library.

Connection Groups

The only real new feature that has been added to 0.9.0 is the concept of connection groups which is something I'm pretty excited about. Internally libAttachSQL uses event loops to supply the non-blocking API. Connection Groups join a bunch of connections together into a group that uses a single event loop. This makes things much more efficient internally and makes applications easier to code too.

Here is a simplified example of how to use it (for a more detailed example see our example in the documentation).

First we need to create the group and add connections to …

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