Interface SQLSessionContext

All Known Implementing Classes:
SQLSessionContextImpl
public interface SQLSessionContext
An implementation of this interface encapsulates some of the SQL session context's state variables, cf. SQL 2003, section 4.37.3, notably those which we need to save and restore when entering a stored procedure or function (which can contain SQL and thus a nested connection), cf. 4.37.3, 4.27.3 and 4.34.1.1.

Presently this set contains the following properties:

  • current role
  • current schema
The standard specifies that the authorization stack be copied onto the new SQL session context before it is pushed (and possibly modifed) with a new cell for the authorization ids (user, role). In our implementation we merge these two stacks for now. Also, the authorization id of current user is not represented yet, since it can not be modified in a session; Derby can not run routines with definer's rights yet.

SQL session context is implemented as follows: Statements at root connection level use the instance held by the the lcc, nested connections maintain instances of SQLSessionContext, held by the activation of the calling statement. This forms a logical stack as required by the standard. The statement context also holds a reference to the current SQLSessionContext.

When a dynamic result set references e.g. current role, the value retrieved will always be that of the current role when the statement is logically executed (inside procedure/function), not the current value when the result set is accessed outside the stored procedure/function. This works since the nested SQL session context is kept by the caller activation, so even though the statement context of the call has been popped, we can get at the final state of the nested SQL session context since the caller's activation is alive as long as dynamic result sets need it).

If more than one nested connection is used inside a shared procedure, they will share the same nested SQL session context. Since the same dynamic call context is involved, this seems correct.

See Also:

  • Method Details

    • setRole

      void setRole(String role)
      Set the SQL role of this SQL connection context

    • getRole

      String getRole()
      Get the SQL role of this SQL connection context

    • setUser

      void setUser(String user)
      Set the SQL current user of this SQL connection context

    • getCurrentUser

      String getCurrentUser()
      Get the SQL current user of this SQL connection context

    • setDefaultSchema

      void setDefaultSchema(SchemaDescriptor sd)
      Set the schema of this SQL connection context

    • getDefaultSchema

      SchemaDescriptor getDefaultSchema()
      Get the schema of this SQL connection context

    • getConstraintModes

      HashMap<UUID,Boolean> getConstraintModes()
      Get a handle to the session's constraint modes. The caller is responsible for any cloning needed.
      Returns:
      constraint modes map

    • setConstraintModes

      void setConstraintModes(HashMap<UUID,Boolean> hm)
      Initialize a inferior session context with the constraint mode map of the parent session context.
      Parameters:
      hm - constraint mode map

    • setDeferred

      void setDeferred(UUID constraintId, boolean deferred)
      Set the constraint mode for this constraint to deferred. If deferred is false, to immediate checking, if true to deferred checking.
      Parameters:
      constraintId - The constraint id
      deferred - The new constraint mode

    • isDeferred

      Boolean isDeferred(UUID constraintId)
      Return Boolean.TRUE if the constraint mode for this constraint/index has been set to deferred, Boolean.FALSE if it has been set to immediate. Any ALL setting is considered also. If the constraint mode hasn't been set for this constraint, return null. The constraint mode is the effectively the initial constraint mode in this case.
      Parameters:
      constraintId - the constraint id
      Returns:
      Boolean.TRUE if the constraint mode for this constraint/index has been set to deferred, Boolean.FALSE if it has been set to immediate.

    • resetConstraintModes

      void resetConstraintModes()
      Clear deferred information for this transaction.

    • setDeferredAll

      void setDeferredAll(Boolean deferred)
      Set the constraint mode for all deferrable constraints to deferred. If deferred is false, set to immediate checking, if true to deferred checking. null is allowed: it means no ALL setting exists.
      Parameters:
      deferred - the mode to set

    • getDeferredAll

      Boolean getDeferredAll()
      Get state of DEFERRED ALL setting.
      Returns:
      True is deferred all constraint mode has been set for this session context. False is deferred immediate has been set for this session context. null means no ALL setting has been made for this context