Change tracking data model

table:changes

• change_id
• user_id
• page_id
• timestamp

table:changes_page

• change_id (fk)
• ...

table:changes_tags

• tag_id
• tag_change_type (tag, untag, define)
• ...

table:changes_comments

• comment_id
• comment_change_type (new, edit, delete)
• ...

table:changes_permission

table:changes_resources (attachments+properties)

table:changes_user

...

Access patterns

• changes site-wide
• changes by a user
• changes for a page (and its subpages!)
• changes for pages 'favorited/starred/subscribed to' by a user
• changes affecting multiple pages should be connected and groupable. This includes cascade permission changes, page moves, page deletes 
• paging support
• filtering support (change type, date range, language, namespace, etc)
• aggregation support (by day)