I am new to heroku ,I can see heroku connect supports Attachment object ,but is it possible to store Salesforce Attachments in Heroku?
In general, Heroku Connect doesn't support binary data. From the FAQ:
Can Heroku Connect sync images from Salesforce?
Heroku Connect does not currently support images or other types of binary data. An alternative approach is to store images in Amazon S3 and sync a simple text field containing a URI for the image between Salesforce and your database.