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Drizzle is described as a "Lightweight SQL Database for Cloud and Web".
The project is about building a database designed for the typical Web
usage patterns for a database. It is being designed for massive
concurrency on modern multi-cpu/core architecture. The code is
originally derived from MySQL.

1. Reliable.
2. Fast and scaleable for modern architecture.
3. Simple design for ease of Install and Management.

Looking at Drizzle

So Drizzle is essentially a fork from the MySQL 6.0 sourcecode,
minus stored procedures, triggers, views, access control, query cache,
and prepared statements. Most non-pluggable storage engines are gone,
as is the MyISAM-only FULLTEXT indexing system.

Stripping down the source tree simplifies refactoring, which is
sorely necessary. See it as a large "spring clean". Various unsavory
things have crept into the code over the years, for pragmatic as well
as business reasons. When unconstrained by those factors, alternative
options open up. This is what Drizzle is exploring.

• For example, the InnoDB storage engine has its own internal parser,
  dealing with the foreign key constraints from a CREATE TABLE statement.
  From a programming perspective, this is a hideous hack.
• FULLTEXT indexing was MyISAM only, and did not scale. SphinxSearch has excellent specs, and can completely replace FULLTEXT while not being bound to a particular engine.
• There are many excellent libraries out there which could be
  utilised. However, because MySQL is also sold under a non-GPL license
  for some customers, this limits the choice considerably and it is not
  able to use any GPL licensed libraries. Using external libraries
  however leverages existing code and expertise and frees up development
  and QA/bugfix time.
• The Drizzle client library will be BSD (rather than GPL) licensed
  to promote adoption, including by closed-source applications. So it is
  based on different code from the well know libmysqlclient which is GPL
  licensed.

Who is Involved

The list of contributors reads like a neat who-is-who of the active
MySQL community, involving some key Sun/MySQL employees but also
ex-employees and long-time community members. There is clearly a lot of
excitement and activity.

Drizzle Down Under

Open Query is closely following Drizzle development, and the
benefits it can bring to many current MySQL users. It's not a full
MySQL replacement, but a large number of users could be well served
with Drizzle once the major refactoring is completed. We hope to
contribute to this effort. This is not a spectator event.

Resources

• Brian Aker's "What If" blog announcing Drizzle
  • A lighter, simpler MySQL (LinuxWorld Podcast)
• Monty's blog entry on Drizzle
• Drizzle project on Launchpad
  • Drizzle Discuss (list)
  • Drizzle Developers (list)
• Drizzle Wiki
• IRC channel #drizzle on Freenode