CBO ? RBO? 很清晰的图示

                            QUERY IN 
                                |
                                | 
                               / /

                 -----------------------------------

                | Is there a hint for table access, | 
                | an ORDERED, FIRST_ROWS or         |
                | ALL_ROWS hint ?                   |
                |                                   |  yes 
                | 7.3+ Does any table have PARALLEL |-------> COST
                |      set ?                        | 
                |      or                           | 
                |      Partition Views involved?    | 
                |                                   | 
                | 8.0+ As above and additionally,   |
                |      Are there any:               |
                |      Index Organised Tables (IOT) | 
                |      or                           | 
                |      Partition Tables involved ?  | 
                |                                   | 
                | 8.1+ As above and additionally,   | 
                |      Are there any:               | 
                |      Domain Indexes (Inter Media) | 
                |      or                           | 
                |      Parallelism set on Indexes   | 
                |      See [NOTE:70008.1]           | 
                |      or                           | 
                |      Parallel instances set on    |

                |      an object                    |

                |      or                           |

                |      Sample clauses               |

                |      (Datawarehousing feature)    |

                |      or                           |

                |      Parallel CTAS                |

                |      or                           |

                |      Function-based indexes       |

                |      or                           |

                |      Reverse Key Indexes          |

                |      or                           |

                |      Query rewrite                |

                |      (materialised views)         |

                |      or                           |

                |      ANSI JOIN syntax is used     |

                |      in the query                 |

                 ----------------------------------- 
                                | 
                                | no 
                                | 
                 -----------------------------------   yes 
                | Is there a RULE hint ?            |-------> RULE 
                 -----------------------------------

                                | 
                                | no 
                                |

                 ----------------------------------- 
                | Is RULE set at SYSTEM or SESSION  |  yes 
                | level and no CHOOSE hint ?        |-------> RULE 
                 ----------------------------------- 
                                | 
                                | no 
                                | 
                 ----------------------------------- 
                | Is ALL_ROWS or FIRST_ROWS set at  |  yes 
                | SYSTEM or SESSION level and no    |-------> COST
                | CHOOSE hint ?                     | 
                 ----------------------------------- 
                                | 
                                | no 
                                | 
                 ----------------------------------- 
                | Are there statistics for any of   |  yes 
                | the tables ?                      |-------> COST 
                 ----------------------------------- 
                                | 
                                | no 
                                | 
                               RULE