There are reported cases from IU and LOI where the student's matrix is stored multiple times in the database. Because the code assumes there is only one matrix the the database (it reads the database and uses the first record that is returned) there can be strange behavior for users when viewing the matrix. Sometimes the content of one record is shown, sometimes the content of another record.

You can use the following query to identify if there are multiple matrix records in the DB:

select worksiteid, scaffolding_id, owner, count
from sakai.osp_matrix m
inner join sakai.osp_scaffolding s on s.id = m.scaffolding_id
group by worksiteid, scaffolding_id, owner
having count > 1
order by count DESC

The resolution is to remove all duplicate records and then put a constraint on the OSP_MATRIX table to make sure there can be only one matrix per student:

create unique index OSP_MATRIX_OWN_SCAFF_UK on OSP_MATRIX(OWNER, SCAFFOLDING_ID);

It's not yet known why there are duplicate records stored in the DB or how to reproduce this behavior.