My Software has an option to archive older data to an read-only marked database which may be stored to a CD or DVD. I created a Viewer program using IBObjects that displays the data. That worked very well up to Firebird 2.0.3.

Now I moved to Firebird 2.1.1. On opening a query with TIBOQuery (IBObjects) I get following error message:

attempted update on read-only database.

I debugged the source code of IBObjects and found out that following statement is used before opening the Query:

SELECT F.RDB$FIELD_NAME F_FieldName
     , F.RDB$RELATION_NAME F_RelationName
     , F.RDB$DEFAULT_SOURCE F_DefaultSource
     , D.RDB$DEFAULT_SOURCE D_DefaultSource
     , D.RDB$FIELD_TYPE D_FieldType
FROM RDB$RELATION_FIELDS F INNER JOIN RDB$FIELDS D
  ON D.RDB$FIELD_NAME = F.RDB$FIELD_SOURCE
WHERE (( F.RDB$DEFAULT_SOURCE IS NOT NULL ) OR ( D.RDB$DEFAULT_SOURCE IS NOT NULL ))
  AND NOT F.RDB$RELATION_NAME STARTING WITH 'RDB$'
ORDER BY 1

I tried some combinitians and found out that follwing statement fails with that error message:

select *
from rdb$relation_fields
where rdb$default_source is not null)

when I change this to:

select *
from rdb$relation_fields
where rdb$default_source <> null)

everything works well. (I didn't knew before that this is allowed...)

I think this is a bug of Firebird 2.1