Table /home/tim/Kobo/KoboReader.sqlite.content_keys
No real idea what this is for. It appears to be indexes into the epub/kepub file. volumeid = contentid where bookid is Null

Generated by
Primary key columns
Columns with indexes
Implied relationships
Excluded column relationships
< n > number of related tables
Column Type Size Nulls Auto Default Children Parents Comments
volumeId varchar 65536,10
content.ContentID Defined in XML R
Looks to be the ContentID of the Main book record from the content table
elementId varchar 65536,10
elementKey varchar 65536,10  √  null

Analyzed at Wed Sep 05 22:43 ADT 2012

Column(s) Type Sort Constraint Name
volumeId + elementId Primary key Asc/Asc sqlite_autoindex_content_keys_1

Close relationships  within of separation: