No transactions support for MySQL
If you are using MySQL first be sure you are using InnoDB, as MyISAM does not support transactions:

http://dev.mysql.com/doc/refman/5.0/en/ansi-diff-transactions.html

Secondly, peewee will not explicitly execute 'begin', 'commit' SQL -- rather it will call the appropriate methods on the db driver.  For example `database.commit()`, `database.rollback()`.
 which is much better for peewee transaction:
database.begin, database.commit()
vs
with database.transaction:
 It doesn't matter, whichever you prefer.
 Thanks! 
Another question:
did peewee place objects into cache for later use?
that means get a object from database at the first time and put it into cache, later will get from cache if it exists in cache. 
 Peewee will cache the results of select queries so that multiple iterations do not cause multiple queries, but other than that there is no caching.

@bakerchen -- if you have questions, for future reference, please use either the [google group](http://groups.google.com/group/peewee-orm) or the #peewee channel on freenode.

As far as I can tell, peewee just toggles autocommit on and off for transaction support. This is not really enough -- you need the START TRANSACTION / COMMIT / ROLLBACK commands issued too.
