While browsing the online documentation I came across this snippet:

From MySQL 4.1.0, the attribute SERIAL can be used as an alias for BIGINT UNSIGNED NOT NULL AUTO_INCREMENT UNIQUE. This is compatibility feature.

(See: http://dev.mysql.com/doc/mysql/en/CREATE_TABLE.html)

The question is of course: for what is this compatibility feature exactly intended? Could it possibly be for PostgreSQL's - non-standard - SERIAL type?

(This wouldn't be the first PostgreSQL compatibility feature, the SELECT clause LIMIT ... OFFSET exists for "compatibility with PostgreSQL": http://dev.mysql.com/doc/mysql/en/SELECT.html )