v_gasmonthsum是个视图,select * from v_gasmonthsum t;带上t查询100s都出不来,去掉t 1秒以内就出来,执行计划一样,有哪位遇到过,这个问题反复验证过,不是偶然的

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但是通过查询select * from v_gasmonthsum t where rownum<1000速度却又恢复正常,总感觉select * from v_gasmonthsum t;这个查询方法是不是少了自动分页提取数据的功能

以下是select * from v_gasmonthsum t执行计划:不带别名t的查询计划雷同

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Plan hash   value: 984768051

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| Id  | Operation                         | Name                   | Rows  | Bytes | Cost (%CPU)| Time     |

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|     0 | SELECT STATEMENT                    |                        |     1 |     224 |  5308   (1)| 00:01:04 |

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|     1 |  NESTED LOOPS                     |                        |     1 |     224 |  5308   (1)| 00:01:04 |

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|     2 |   NESTED LOOPS                    |                        |     1 |     211 |  5304   (1)| 00:01:04 |

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|     3 |    NESTED LOOPS                   |                        |     1 |     117 |  5298   (1)| 00:01:04 |

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|     4 |     VIEW                          | VW_SQ_1                |   213 | 11076 |  4870     (1)| 00:00:59 |

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|     5 |      HASH GROUP BY                |                        |   213 | 11076 |  4870     (1)| 00:00:59 |

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|*    6 |       FILTER                      |                        |       |         |            |          |

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|     7 |        TABLE ACCESS BY INDEX   ROWID| GASOUTPUTMONTHDATA     |   213 | 11076 |  4870     (1)| 00:00:59 |

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|*    8 |         INDEX FULL SCAN           | IDX_GASOUTPUTMONTHDATA |  8726 |         |  4766   (1)| 00:00:58 |

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|*    9 |     TABLE ACCESS BY INDEX   ROWID   | GASOUTPUTMONTHDATA     |       1 |    65 |     3     (0)| 00:00:01 |

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|* 10 |      INDEX RANGE SCAN             | IDX_GASOUTPUTMONTHDATA |     1 |         |     2   (0)| 00:00:01 |

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|    11 |    INLIST ITERATOR                |                        |       |         |            |          |

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|    12 |     TABLE ACCESS BY INDEX   ROWID   | GASFACMONTHDATA        |       1 |    94 |     6     (0)| 00:00:01 |

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|* 13 |      INDEX RANGE SCAN             | IDX_GASFACMONTHDATA    |       1 |       |     5     (0)| 00:00:01 |

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|* 14 |   VIEW PUSHED PREDICATE           | VW_SQ_2                |     1 |      13 |     4   (0)| 00:00:01 |

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|* 15 |    FILTER                         |                        |       |         |            |          |

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|    16 |     SORT AGGREGATE                |                        |     1 |      55 |            |          |

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|* 17 |      FILTER                       |                        |       |         |            |          |

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|* 18 |       INDEX RANGE SCAN            | IDX_GASFACMONTHDATA    |       1 |    55 |     4     (0)| 00:00:01 |

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Predicate Information (identified by   operation id):

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6 - filter(201801

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8 - access("G"."YEARANDMONTH">=201801 AND   "G"."YEARANDMONTH"

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)))

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filter("G"."YEARANDMONTH">=201801 AND   "G"."YEARANDMONTH"

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)))

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9 - filter("T"."SHAREID"="MAX(SHAREID)")

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10 - access("T"."PSCODE"="ITEM_1" AND   "T"."OUTPUTCODE"="ITEM_3" AND   "T"."YEARANDMONTH"="ITEM_2")

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filter("T"."YEARANDMONTH">=201801 AND   "T"."YEARANDMONTH"

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)))

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13 -   access("T"."PSCODE"="T"."PSCODE" AND   "T"."OUTPUTCODE"="T"."OUTPUTCODE"   AND

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("T"."POLLUTANTCODE"='001' OR   "T"."POLLUTANTCODE"='002' OR   "T"."POLLUTANTCODE"='003') AND

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"T"."YEARANDMONTH"="T"."YEARANDMONTH")

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filter("T"."YEARANDMONTH">=201801 AND   "T"."YEARANDMONTH"

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)))

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14 -   filter(SYS_OP_UNDESCEND(SYS_OP_DESCEND("SHAREID"))="MAX(SHAREID)")

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15 - filter(COUNT(*)>0 AND   201801

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17 -   filter(TO_NUMBER(TO_CHAR(SYSDATE@!,'YYYYMM'))>"T"."YEARANDMONTH"   AND

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201801<="T"."YEARANDMONTH" AND   201801

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18 -   access("G"."PSCODE"="T"."PSCODE" AND   "G"."OUTPUTCODE"="T"."OUTPUTCODE"   AND

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"G"."POLLUTANTCODE"="T"."POLLUTANTCODE"   AND   "G"."YEARANDMONTH"="T"."YEARANDMONTH")

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filter("G"."YEARANDMONTH">=201801 AND   "G"."YEARANDMONTH"

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)))

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Note

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- dynamic sampling used for this statement (level=2)

文章题目：ORACLE视图加上别名查询非常慢,去掉之后正常
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