By default, Hibernate uses a BLOB type (limited to 64 KB) instead of the LONGBLOB type (limited to 2 GB). When migrating attachments to the database in Confluence 2.2, they get truncated to 64 KB without an error.

Two things we should do:

• use the LONGBLOB type in MySQL for attachment storage
• use the 'Traditional' SQL mode in MySQL so errors when writing data are raised as errors rather than silently dropped.

http://dev.mysql.com/doc/refman/5.0/en/server-sql-mode.html