In my last post I covered how to use the query rewrite framework to write your own pre-parse plugin. The interface is simplistic: a string goes in, a string comes out, and the rest is up to your plugin’s internal workings. It doesn’t interact that much with the server. Today I am going to show you the other type of plugins that rewrite queries, post-parse query rewrite plugins. This type is, out of necessity, more tightly coupled with the server; it operates on the internal data structures that make up the query’s parse tree.

Creating the Plugin

Declaring the plugin is similar to declaring a pre-parse plugin: you declare the plugin in the usual way but with the addition of a specific plugin descriptor for the post-parse query rewrite plugin type. This is a struct, as usual:

struct …

With the query rewrite framework in the latest MySQL (Optimizer/InnoDB/Replication) labs release, you get the opportunity to author plugins that can rewrite queries. You can choose whether to rewrite the queries before and/or after parsing. Today I am going to walk you through how to write a pre-parse query rewrite plugin.

When would you want to use a pre-parse query rewrite plugin? The greatest benefit compared to post-parse rewrites — which I cover in a separate post — is the efficiency, especially the lack of overhead for those queries that are actually rewritten. Typical cases where you may want to write a pre-parse plugin are:

• When you want to remove certain specific clauses from queries. For example, perhaps you want to remove all ENGINE …

Why Query Rewrites?

Now that the cost model project is progressing, most of you are going to notice execution plan changes. In the vast majority of the cases, the changes will be for the better, and some bugs with a long history will finally be closed. In some cases, however, you will notice that your queries run slower. This is inevitable: even if the MySQL optimizer is doing a much better job with the information it has, it may still be the case that the information was incomplete and that the best plan was, in fact, found by not trusting that information! Normally, we would just say “add an optimizer hint” and be over with it. But sometimes you can’t do that. For instance your query could be auto-generated from an application that you have no control over. This is why you want to intervene right before the …

Today before Ivan’s tutorial, he told me that in the 10.0.5 virtual machine images he created, he couldn’t find the Cassandra storage engine. I told him it had to be installed separately, and this is true – you have to install some engines separately!

When you do a yum install MariaDB-server MariaDB-client like the installation instructions tell you to do, you don’t get all storage engines (so running SHOW ENGINES might have you wondering what happened to a bunch of engines). This can easily be seen by doing a yum search MariaDB. On a CentOS 6.4 server with the MariaDB 10.0 repository configured, you should see the following:

MariaDB-cassandra-engine.x86_64 : MariaDB: a very fast and robust SQL database server
MariaDB-client.x86_64 : MariaDB: a very fast and robust SQL database server
MariaDB-common.x86_64 : MariaDB: a very fast and robust SQL …

Just a quick post to note that the content from my hands-on lab at MySQL Connect (“MySQL Enterprise Features in Practice”) has been uploaded to the content catalog, and can be found here.  This includes the 36-page lab manual and example commands and programs (mostly in Java; the package includes both compiled and source code).  For those who attended the lab, this is an opportunity to complete the exercises we didn’t get to in the 2.5 hours, and for those who missed it, an opportunity to learn more about the features and capabilities of key MySQL Enterprise products and features such as MySQL Enterprise Audit plugin, MySQL Enterprise Monitor and MySQL Enterprise Security (PAM plugin).  I hope to expand on the lab content …

I distinctly remember creating and committing this code... and it has largely not changed. Yet, it seems that my name was scrubbed from its history.

$ bzr blame -q include/mysql/plugin_audit.h | grep antony | wc -l

       0

Sad-face.

=-(

I previously published stored programs to help implement a (more) comprehensive password policy in MySQL 5.6, building on the password complexity plugin now available in MySQL 5.6.  This proof-of-concept has been expanded recently, and the updated package is available here.  There’s a few notable changes to the earlier version:

Moved all created objects out of mysql system database

The mysql database is meant for system tables, and I try to keep everything not directly managed by the MySQL server out of that database.  The initial proof-of-concept implementation violated this principal – the update corrects this by creating and using a new password_policy database …

LinkedIn has what they call "inDays" where employees may so something interesting which may not be directly related to their day job. I spent my inDay by porting my old WL820 project (External Language Stored Procedures) to MariaDB 5.3.

The code, as usual, is available on LaunchPad ... To get the branch, simply do:

bzr branch lp:~atcurtis/maria/5.3-wl820 The test cases pass... I haven't tested

Pluggable M3 (Monitis Monitor Manager) Framework

Who needs an introduction about M3? – Perhaps no one!
After gaining some reputation with M3, providing extra-easy integration of any monitor into Monitis it was time to take it to the next level.

Generally speaking, the work flow of M3 was described in detail in this article.

After some thought and design, we’ve decided it’d be best if M3 was pluggable. Pluggable in terms of being able to easily add execution and parsing plugins.
The interface and behavior of M3 …

In this primer I will show how to improve the security of your MariaDB installation by using two-step verification and how to use it from your Windows GUI client.

Let’s suppose you have your data in MariaDB, installed, say, on Ubuntu. And your users connect to it to run ad hoc queries, using some sort of a Windows GUI client. You don’t want them to write the access password on post-it notes or have it auto-entered by the client. And you don’t want anyone see the password when one of the salespersons connects to the mother ship from his laptop in the Internet café. So you decide to use the two-step verification, just like Google does, to secure the access to the data.

If you don’t know what a “two-step verification” is, see, for example, this introductory video by Google.

So, 2-step verification looks great, but how …