Berkeley DB (BDB) is undoubtedly the workhorse among the opensource embedded database engines. It started as a university project in the mid-eighties and was further developed by Sleepycat Software, until it got acquired by Oracle in February 2006.

I had the impression that BDB had lost a lot of its popularity among opensource developers to SQLite in recent times, which has evolved into becoming the default choice for developers looking for an embedded data store. I'd assume primarily because the code is not released under any particular license, but put in the public domain …

Brian wrote recently Where did all of the MySQL Developers Go?, while over in Drizzle land they have been accepted for the Google Summer of code along with many other open source projects. MySQL from my observation a noticeable absentee.

Historically, the lack of opportunity to enable community contributions and see them implemented in say under 5 years, has really hurt MySQL in recent times. There is plenty of history here so that’s not worth repeating. The current landscape of patches, forks and custom MySQL binaries for storage engine provider has provided a boom of innovation that sadly is now lost from the core MySQL product.

In Drizzle, community contribution is actively sought and a good portion of committed code is not from the core Drizzle …

Since the time that I’ve been using MySQL I have filed quite a few bug reports. Some of these have been fixed and many of the bug reports are actually new feature requests. While working with MySQL Enterprise Monitor I’ve probably filed more feature requests than bug reports.

That’s fine of course and my opinion of what is needed in MySQL or Merlin is one thing,  yours or the MySQL developers is something else. We all have our own needs and find things missing which would solve our specific problems.

If I have ten feature requests open and only one could be added to the software I’d also like to be able to say: this feature is the most important one for me.

However, it seems to me that there is no easy way in the mysql bug tracker at the moment to group together different types of new feature requests into groups of related features and then see the different types of …

1. Common MySQL Queries -- a useful reference.
2. MySociety's Next 12 Months -- two new projects, FixMyTransport and "Project Fosbury". The latter is a more general tool to help people organise their own campaigns for change.
3. riak -- scalable key-value store with JSON interface. (via joshua on Delicious)
4. Notes from NoSQL Live Boston -- full of juicy nuggets of info from the NoSQL conference.

…

A key differentiator in Drizzle from it’s original MySQL roots is user based authentication. Gone is the host/user and schema/table/column model that was stored in the MyISAM based mysql.user table.

Authentication is now completely pluggable, leveraging existing systems such as PAM, LDAP via PAM and Http authentication.

In this post I’ll talk about HTTP authentication which requires an external http server to implement successfully. You can look at Part 1 for …

A key differentiator in Drizzle from it’s original MySQL roots is user based authentication. Gone is the host/user and schema/table/column model that was stored in the MyISAM based mysql.user table.

Authentication is now completely pluggable, leveraging existing systems such as PAM, LDAP via PAM and Http authentication.

In this post I’ll talk about PAM authentication which is effectively your current Linux based user security.

This information is based on the current …

This week with a client I saw ext4 used for the first time on a production MySQL system which was running Ubuntu 9.10 (Karmic Koala). I observe today while installing 9.10 Server locally that ext4 is the default option. The ext4 filesystem is described as better performance, reliability and features while there is also information about improvements in journaling.

At OSCON 2009 I attended a presentation on Linux Filesystem Performance for Databases by Selena Deckelmann in which ext4 was included. While providing some improvements in sequential reading and writing, there were issue with random I/O which is the key for RDBMS products.

Is the RAID configuration (e.g. RAID 5, RAID 10), strip size, buffer caches, LVM …

With the recent news by Brian about the Data Dictionary in Drizzle replacing the INFORMATION_SCHEMA, I was looking into the server status variables (aka INFORMATION_SCHEMA.GLOBAL_STATUS) and I came across an interesting discovery.

select * from data_dictionary.global_status;
...
| Table_locks_immediate      | 0              |
| Table_locks_waited         | 0              |
| Threads_connected          | 8134064        |
| Uptime                     | 332            |
| Uptime_since_flush_status  | 332            |
+----------------------------+----------------+
51 rows in set (0 sec)

This only retrieved 51 rows, which is way less then previous. What I wanted was clearly missing, all the old com_ status variables. Looking at what the data_dictionary actually has available revealed a new table.

drizzle> select * from data_dictionary.global_statements; …

As part of my upcoming FREE my.cnf check advice I first need to ask people to provide the current MySQL configuration file commonly found as a file named my.cnf

If only that question was easy to answer!

Use of configuration files

MySQL will by default use at least one configuration file from the following defaults. MySQL also uses a cascade approach for configuration files. When you have multiple files in the appropriate paths you can see unexpected behavior when you override certain values in different files.

You can however for example specify –no-defaults to use no configuration file, or add options to your command line execution, so even looking at all configuration files is no guarantee of your operating configuration.

However for most environments, these complexities do not exist.

…

MySQL has a number of global buffers, i.e. your SGA. There are also a number of per session/thread buffers that combined with other memory usage constitutes an unbounded PGA. One of the most common errors in mis-configured MySQL environments is the setting of the 4 primary per session buffers thinking they are global buffers.

Global buffers include:

• • key_buffer_size – For MyISAM Indexes (note you can define multiple key_buffer’s The MyISAM Key Cache)
  • innodb_buffer_pool_size – For Innodb …