Email cache database design

Can you advice how to store email MessagePart hierarchy into database (SQLite)?

Parts can be of开发者_运维知识库 different MIME type (text, image, etc). Also they can be multipart.

The only way I see is to store all parts in single MessageParts table with content_bytes field and mime_type field + parent_id for multipart

Is it ok? Is there some better way?

Thanks!

Look up "generalization specialization relational modeling" and you will find some excellent articles on the web. This is well understood, but often overlooked.