Where is Scaffolding Data Stored?

Answer

Scaffolding data is stored in table OS_PROPERTYENTRY with entity_id as foreign key to CONTENT.contentid.

the history/versioning of Confluence leads to many entries with the same OS_PROPERTYENTRY.entity_id
the latest/current version is the entry with OS_PROPERTYENTRY.entity_key = "~metadata." + n, where n = CONTENT.version

Here is an SQL example to get latest version of a page Scaffolding data.

select c.contentid, c.title, c.version, o.text_val

from CONTENT c, OS_PROPERTYENTRY o 

where c.title='My Page' and c.prevver is NULL and c.contentid=o.entity_id and o.entity_key=concat('~metadata.',c.version)