KDb/TODOs/User data

Design page for task: Support for user data storage.

• Started: Jstaniek (talk) 11:01, 13 August 2012 (BST)
• Wish #??

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