KDb/TODOs/User data
Design page for task: Support for user data storage.
Rationale
Among others, this feature is needed by the Remember table column widths feature.
Requirements
- Backward compatibility
- Older Kexi versions should just ignore the data
- Per user-separation
- How: based on user name, this implies that updates are needed when user name changes
- How: in separate table kexi__userdata
- Backend independence - should work with the SQLite driver as well the server backends (any table-based backends)
- How: achieved using standard db table, related to objects
- Portability to Predicate and 100% schema-compatible with Predicate
- How: API will change but table schema will stay the same
- Lifetime
- Data should be created on demand, e.g. on first change of setting made by the user
- kexi__userdata table should be created on project creation, after kexi__objects is created
- For existing projects created with older KexiDB, kexi__userdata is missing. It should be created after opening (if there are permissions).
- No-break behaviour for read-only connections
- In case of no write access (e.g. because of the read-only connection mode), it can logged to the debug output as a warning
- Behaviour for User Mode connections
- User Mode should not limit the feature
kexi__userdata schema
kexi__userdata
d_user Text NOT NULL -- user name
o_id Integer UNSIGNED NOT NULL -- n-to-1 relationship to kexi__objects.o_id
d_sub_id Text NOT NULL -- sub-identifier of the data
-- (not i18n'd, dependent on object type, should not be tool long)
d_data LongText -- actual data serialized to text
Notes:
- Cascade update and delete of kexi__userdata records should happen based on kexi__objects
- No primary key but (d_user, o_id, d_name) should be unique, so having a key would be useful
- Data of global scope can be stored by adding a new 'data' object type, adding single record to kexi__objects, then relating to it in kexi__userdata