When upgrading from Confluence 6.2.0 to Confluence 7+, how do attachment content properties migrate?

[P]

When upgrading from Confluence 6.2.0 to Confluence 7 or higher, how do attachments stored in the database with custom content properties get properly migrated over to the file system ?

In our version of Confluence, attachments are currently stored in the database along with a custom content property using the ContentPropertyManager.setTextProperty() and ContentPropertyManager.getTextProperty().

For database developers reading this, you already know this content property is stored in the OS_PROPERTYENTRY table under the "text_val" column

My question: When upgrading from Confluence 6.2.0 to Confluence 7 or higher, will our custom content property migrate into the file system or remain in OS_PROPERTYENTRY? 

If it migrates to the file system alongside the attachment itself, can I still use ContentPropertyManager's getter and setter ? 

Also, is there some kind of a script that can check whether all the content properties associated with an attachment have been properly migrated during an upgrade from the database to the file system? Checking it works correctly for a few attachments should be simple, but if there are over 10000 attachments then checking if each one's associated content property was properly migrated would become cumbersome. A script that could iterate through all attachments in the database and verify the content properties associated with each attachment were properly migrated would save a lot of time.

[Moses Thomas · Accepted solution]

@P    Confluence 5.4 and earlier gives administrators the option to store attachments in the database that Confluence is configured to use.

By default Confluence stores attachments in the home directory (e.g. in a file system)  for version  since 5.5  and above.

Class FileSystemAttachmentDataDao 

Now storing attachments in the database is not an option for your confluence version it is(Deprecated). That means  that you are not given the option to  store attachments in the database.

Back  to your question,  it says in Interface ContentPropertyManager   instead of using this interface you should use Class ContentProperties   and  the class  content properties is also supported for confluence 7.0  Class ContentProperties conf v.7.0.x 

In addition  your custom content property  will most likely not migrate into the file system it should  remain in OS_PROPERTYENTRY;  but i suggest  your try  to upgrade in the test environment to certainly verify this   before doing it in  the production environment.

There is also information here  on migrating  attachment  from DB  to file system should in-case you are still using attachment stored  in DB. Attachment Storage Configuration 

NOTE  if you are already using attachment on file system  then the migration pop up with not appear in  Attachment storage  setting.

Best regards,

Moses