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.