[Casimiro Noteví]

Creo que tendrás que contar los registros por cada tabla, prueba este procedure.

Código SQL [-]
CREATE OR ALTER PROCEDURE ContarRegistrosTablas RETURNS (
    TABLA VARCHAR(31),
    CANTIDAD INTEGER
)
AS
BEGIN
  /* Ejemplo: select * from ContarRegistrosTablas order by 2 desc */
  For Select RDB$Relation_Name From RDB$Relations
  Where (RDB$System_Flag = 0) And (RDB$View_BLR Is Null)
  Order By RDB$Relation_Name Into :Tabla Do
  Begin
    Execute Statement 'Select Count (*) From ' || :Tabla Into :Cantidad;
    Suspend;
  End
End