Storage Engines

MySQL has components called Storage Engines, this engines determine the way information is stored. Engines have different features and may be used to cover different requirements. For example, MyIsam is the default engine and the Information_Schema - the equivalent to Oracle’s Dictionary - is stored using it. One thing that will surprise Oracle DBA’s is that this engine does not support transactions (you do not need to commit, but you cannot rollback and you cannot define a transaction unit).
MyIsam is the most usual engine, but it is not the only one. InnoDB, an engine provided by InnoBase, a company acquired by Oracle Corp, is another one. It supports transactions and has certain similar concepts to Oracle Database, for example tables are stored in a tablespace (MyIsam tables are stored in a file each one).

Mixing engines

You should choose which is the right engine for your application and it is possible to use several engines at the same time, in the same query. You must be careful when doing things like this as trying to rollback a transaction involving both transactional and non-transactional engines may give you unexpected results: rollback transactional tables but leaving the rest untouched.

Engine availability

Some storage engines are always available, others must be enabled. In MySQL 5.0 engines must be configured at build time and may be disabled/enabled at startup time later versions support dynamic engine loading. You must enable only the engines you plan to use as they consume memory.

Optimization

Having so many different engine configurations poses a challenge for the MySQL optimizer, as the optimal execution plan must be decided outside the engine. What MySQL does is to ask each storage engine information about tables and indexes involved in the query.

Engine migration

It is possible to migrate a table from one engine to another but you must be careful as some table features will be lost if they are not supported by the engine.
Migration may be performed via alter table, dump and import (export/import equivalent) or using sql create/insert/select.

My is the name of MySQL co-founder Monty Widenius’s daughter.

Did you know that Oracle is a name conceived in the CIA?

Oracle Corporation founders Larry Ellison and Bob Miner had been working on a CIA project based on the paper written by Edgar F. Codd about the Relational Model. This project was called Oracle as the Agency wanted to build a system able to answer any question. Unsurprisingly the project did not succeed but Larry and Bob saw the opportunity and decided to keep on working on that technology.

But, who is Sakila?

Sakila is the name of the dolphin you may see in the MySQL logo. This name was chosen by the MySQL founders in a contest called “Name the Dolphin”. Ambrose Twebaze, an Open Source software developer from Swaziland, suggested the winning name.

More about dolphins and oracles

The Dolphin is a DC Comic’s superheroine. She has superhuman strength and is adapted for deep subaquatic life. She was Aquaman lover and later married Tempest. Cerdian is their son. It is unknown their situation but it is supposed they are alive.
Oracle is one of the names of Barbara Gordon, another DC Comics character. She was first know as Batgirl but she was retired. While in retirement she was shoot by the Joker, confining her in a wheel chair. Later she reappeared as Oracle, with skills in Eskima and extraordinary hacking abilities.

Sources

http://www.orafaq.com/faqora.htm
http://en.wikipedia.org/wiki/Oracle_Corporation
http://www.mysql.com/news-and-events/generate-article.php?id=77
http://dev.mysql.com/doc/refman/5.0/en/history.html
http://en.wikipedia.org/wiki/Dolphin_(comics)
http://en.wikipedia.org/wiki/Barbara_Gordon