对比前后执行计划，发现问题
 链接： http://www.dbaroad.me/archives/2008/11/find-sqlplan-differ.html
检查数据库,发现实例2 latch free较高，TOPAS发现操作系统CPU较高
 
      2 latch free                3487375171 PGATE        7
     2 buffer busy global CR      3487375171 PGATE        7
检查导致latch free的SQL语句，如下：
 
((SELECT a.PT_id, b.acct_code,
         NVL (c.description, 'EFG') certificate_type,
         NVL (d.description, 'ABC') payed_method,
         NVL (e.orgniztion, 'EFG') PT_location,
         TO_CHAR (pay_date, 'YYYY-MM-DD HH24:MI:SS') PT_time,
         a.amount PT_amount, a.operation_type operation_type
    FROM PT_75 a,
         acct_75 b,
         sys_field_desc c,
         sys_field_desc d,
         (SELECT x.operator_id, NVL (o.party_role_name, 'EFG') orgniztion
            FROM sys_operator x, party_roley, party_role_relat z,
                 party_role o
           WHERE x.party_id = y.party_id(+)
             AND y.party_role_id = z.party2_role_id(+)
             AND z.party1_role_id = o.party_role_id(+)
             AND NVL (x.region_id, 0) IN (75, 0)) e
   WHERE a.acct_id = b.acct_id
     AND a.amount != 0
     AND a.staff_id = e.operator_id(+)
     AND c.table_name = 'PT'
     AND c.column_name = 'CERTIFICATE_TYPE'
     AND a.certificate_type = c.VALUE(+)
     AND d.table_name = 'PT_PLAN'
     AND d.column_name = 'PT_METHOD'
     AND a.payed_method = d.VALUE(+)
     AND b.acct_code = :1
     AND TO_CHAR (a.pay_date, 'yyyymmdd') >= :2
     AND TO_CHAR (a.pay_date, 'yyyymmdd') < = :3))
ORDER BY pay_date DESC
查看其执行计划如下：
 
[Execution Plan Information]
-------------------------------------------------------------------------------------------------
| Operation                                       | PHV/Object Name     |  Rows | Bytes| Cost   |
-------------------------------------------------------------------------------------------------
|00[00]SELECT STATEMENT                           |---- 3487375171.0 ---|       |      |     28 |
|01[01]SORT ORDER BY                              |                     |     1 |  218 |     28 |
|02[02] FILTER                                    |                     |       |      |        |
|03[03]  NESTED LOOPS                             |                     |     1 |  218 |     12 |
|04[04]   NESTED LOOPS OUTER                      |                     |     1 |  196 |     10 |
|05[05]    NESTED LOOPS                           |                     |     1 |  138 |      9 |
|06[06]     MERGE JOIN CARTESIAN                  |                     |     1 |   86 |      4 |
|07[07]      TABLE ACCESS BY INDEX ROWID          |SYS_FIELD_DESC       |     1 |   43 |      2 |
|08[08]       INDEX RANGE SCAN                    |SYS_FIELD_DESC_1     |     1 |      |      1 |
|09[07]      BUFFER SORT                          |                     |     1 |   43 |      2 |
|10[08]       TABLE ACCESS FULL                   |SYS_FIELD_DESC       |     1 |   43 |      2 |
|11[06]     TABLE ACCESS BY GLOBAL INDEX ROWID    |PT_75                |     1 |   52 |      5 |
|12[07]      INDEX RANGE SCAN                     |IDX_PT_75_DAY        |    56K|      |      1 |
|13[05]    VIEW PUSHED PREDICATE                  |                     |    10 |  580 |      1 |
|14[06]     NESTED LOOPS OUTER                    |                     |     1 |   58 |      7 |
|15[07]      NESTED LOOPS OUTER                   |                     |     1 |   42 |      6 |
|16[08]       NESTED LOOPS OUTER                  |                     |     1 |   29 |      4 |
|17[09]        TABLE ACCESS BY INDEX ROWID        |SYS_OPERATOR         |     1 |   15 |      2 |
|18[10]         INDEX UNIQUE SCAN                 |PK_SYS_OPERATOR      |     1 |      |      1 |
|19[09]        TABLE ACCESS BY INDEX ROWID        |PARTY_ROLE           |     1 |   14 |      2 |
|20[10]         INDEX RANGE SCAN                  |IDX_PARTYROLE_PARTY_ |     1 |      |      1 |
|21[08]       TABLE ACCESS BY INDEX ROWID         |PARTY_ROLE_RELAT     |     1 |   13 |      2 |
|22[09]        INDEX RANGE SCAN                   |IDX_PARTY2_ROLE_ID   |     1 |      |      1 |
|23[07]      TABLE ACCESS BY INDEX ROWID          |PARTY_ROLE           |     1 |   16 |      1 |
|24[08]       INDEX UNIQUE SCAN                   |PK_PARTY_ROLE        |     1 |      |        |
|25[04]   TABLE ACCESS BY INDEX ROWID             |ACCT_75              |     1 |   22 |      2 |
|26[05]    INDEX UNIQUE SCAN                      |PK_ACCT_75           |     1 |      |      1 |
-------------------------------------------------------------------
 
[Predicate Information]
 
-------------------------------------------------------------------
 
         2 filter::2< =:3
         8 access:"D"."TABLE_NAME"='PT_PLAN' AND "D"."COLUMN_NAME"='PT_
           METHOD'
 
        10 filter:"C"."TABLE_NAME"='PT' AND "C"."COLUMN_NAME"='CERTIFICATE_T
           YPE'
 
        11 filter:"A"."AMOUNT"<>0 AND "A"."CERTIFICATE_TYPE"="C"."VALUE" AND "A".
           "PAYED_METHOD"="D"."VALUE"
 
        12 access:TO_CHAR("A"."PAY_DATE",'yyyymmdd')>=:2 AND TO_CHAR("A"."PAY_DAT
           E",'yyyymmdd')< =:3
 
        17 filter:NVL("X"."REGION_ID",0)=75 OR NVL("X"."REGION_ID",0)=0
        18 access:"A"."STAFF_ID"="X"."OPERATOR_ID"
        20 access:"X"."PARTY_ID"="Y"."PARTY_ID"(+)
        22 access:"Y"."PARTY_ROLE_ID"="Z"."PARTY2_ROLE_ID"(+)
        24 access:"Z"."PARTY1_ROLE_ID"="O"."PARTY_ROLE_ID"(+)
        25 filter:"B"."ACCT_CODE"=:1
        26 access:"A"."ACCT_ID"="B"."ACCT_ID"
查看其历史执行计划信息：（通过查询 stats$sql_plan_usage）
 
-------------------------------------------  Instance 1 ------------------------------------
 
INSTANCE_NUMBER SNAP_ID SNAP_TIME           HASH_VALUE PLAN_HASH_VALUE       COST OPTIMIZER
--------------- ------- ------------------- ---------- --------------- ---------- ----------
              1   95945 2008-10-30 09:05:43 3487375171       378545151         28 CHOOSE
              1   95944 2008-10-30 08:45:43 3487375171       378545151         28 CHOOSE
              1   95940 2008-10-30 08:25:44 3487375171       378545151         28 CHOOSE
              1   95939 2008-10-30 08:05:43 3487375171       378545151         28 CHOOSE
              1   95938 2008-10-30 07:45:43 3487375171       378545151         28 CHOOSE
              1   95937 2008-10-30 07:25:43 3487375171       378545151         28 CHOOSE
              1   95936 2008-10-30 07:05:43 3487375171       378545151         28 CHOOSE
              1   95935 2008-10-30 06:45:43 3487375171       378545151         28 CHOOSE
              1   95934 2008-10-30 06:25:42 3487375171       378545151         28 CHOOSE
              1   95923 2008-10-30 06:05:42 3487375171       378545151         28 CHOOSE
              1   95922 2008-10-30 05:45:43 3487375171       378545151         28 CHOOSE
              1   95921 2008-10-30 05:25:44 3487375171       378545151         28 CHOOSE
              1   95920 2008-10-30 05:05:42 3487375171       378545151         28 CHOOSE
              1   95919 2008-10-30 04:45:43 3487375171       378545151         28 CHOOSE
              1   95918 2008-10-30 04:25:43 3487375171       378545151         28 CHOOSE
              1   95917 2008-10-30 04:05:42 3487375171       378545151         28 CHOOSE
              1   95916 2008-10-30 03:45:42 3487375171       378545151         28 CHOOSE
              1   95915 2008-10-30 03:25:42 3487375171       378545151         28 CHOOSE
              1   95914 2008-10-30 03:05:43 3487375171       378545151         28 CHOOSE
              1   95903 2008-10-30 02:45:42 3487375171       378545151         28 CHOOSE
              1   95902 2008-10-30 02:25:42 3487375171       378545151         28 CHOOSE
              1   95901 2008-10-30 02:05:42 3487375171       378545151         28 CHOOSE
              1   95900 2008-10-30 01:45:42 3487375171       378545151         28 CHOOSE
              1   95899 2008-10-30 01:25:42 3487375171       378545151         28 CHOOSE
              1   95898 2008-10-30 01:05:42 3487375171       378545151         28 CHOOSE
              1   95897 2008-10-30 00:45:43 3487375171       378545151         28 CHOOSE
              1   95896 2008-10-30 00:25:42 3487375171       378545151         28 CHOOSE
              1   95895 2008-10-30 00:05:43 3487375171       378545151         28 CHOOSE
              1   95894 2008-10-29 23:45:42 3487375171       378545151         28 CHOOSE
              1   95883 2008-10-29 23:25:42 3487375171       378545151         28 CHOOSE
              1   95881 2008-10-29 22:45:42 3487375171       177359624        223 CHOOSE
              1   95880 2008-10-29 22:25:41 3487375171       177359624        223 CHOOSE
              1   95879 2008-10-29 22:05:42 3487375171       177359624        223 CHOOSE
              1   95878 2008-10-29 21:45:42 3487375171       177359624        223 CHOOSE
              1   95877 2008-10-29 21:25:42 3487375171       177359624        223 CHOOSE
              1   95876 2008-10-29 21:05:42 3487375171       177359624        223 CHOOSE
              1   95875 2008-10-29 20:45:42 3487375171       177359624        223 CHOOSE
              1   95874 2008-10-29 20:25:42 3487375171       177359624        223 CHOOSE
              1   95863 2008-10-29 20:05:42 3487375171       177359624        223 CHOOSE
              1   95862 2008-10-29 19:45:42 3487375171       177359624        223 CHOOSE
              1   95861 2008-10-29 19:25:42 3487375171       177359624        223 CHOOSE
              1   95860 2008-10-29 19:05:42 3487375171       177359624        223 CHOOSE
              1   95859 2008-10-29 18:45:42 3487375171       177359624        223 CHOOSE
              1   95858 2008-10-29 18:25:42 3487375171       177359624        223 CHOOSE
              1   95857 2008-10-29 18:05:41 3487375171       177359624        223 CHOOSE
              1   95856 2008-10-29 17:45:41 3487375171       177359624        223 CHOOSE
              1   95855 2008-10-29 17:25:41 3487375171       177359624        223 CHOOSE
              1   95854 2008-10-29 17:05:42 3487375171       177359624        223 CHOOSE
              1   95838 2008-10-29 16:45:42 3487375171       177359624        223 CHOOSE
              1   95805 2008-10-29 11:05:41 3487375171       177359624        223 CHOOSE
              1   95761 2008-10-29 08:05:41 3487375171       177359624        223 CHOOSE
              1   95760 2008-10-29 07:45:41 3487375171       177359624        223 CHOOSE
              1   95759 2008-10-29 07:25:41 3487375171       177359624        223 CHOOSE
              1   95758 2008-10-29 07:05:42 3487375171       177359624        223 CHOOSE
              1   95757 2008-10-29 06:45:41 3487375171       177359624        223 CHOOSE
              1   95756 2008-10-29 06:25:40 3487375171       177359624        223 CHOOSE
              1   95755 2008-10-29 06:05:41 3487375171       177359624        223 CHOOSE
              1   95754 2008-10-29 05:45:41 3487375171       177359624        223 CHOOSE
              1   95743 2008-10-29 05:25:41 3487375171       177359624        223 CHOOSE
              1   95742 2008-10-29 05:05:41 3487375171       177359624        223 CHOOSE
              1   95741 2008-10-29 04:45:40 3487375171       177359624        223 CHOOSE
              1   95740 2008-10-29 04:25:41 3487375171       177359624        223 CHOOSE
              1   95739 2008-10-29 04:05:40 3487375171       177359624        223 CHOOSE
              1   95738 2008-10-29 03:45:40 3487375171       177359624        223 CHOOSE
              1   95737 2008-10-29 03:25:41 3487375171       177359624        223 CHOOSE
              1   95736 2008-10-29 03:05:40 3487375171       177359624        223 CHOOSE
              1   95735 2008-10-29 02:45:41 3487375171       177359624        223 CHOOSE
              1   95734 2008-10-29 02:25:42 3487375171       177359624        223 CHOOSE
              1   95723 2008-10-29 02:05:40 3487375171       177359624        223 CHOOSE
              1   95722 2008-10-29 01:45:41 3487375171       177359624        223 CHOOSE
              1   95721 2008-10-29 01:25:41 3487375171       177359624        223 CHOOSE
              1   95720 2008-10-29 01:05:41 3487375171       177359624        223 CHOOSE
              1   95719 2008-10-29 00:45:41 3487375171       177359624        223 CHOOSE
              1   95718 2008-10-29 00:25:41 3487375171       177359624        223 CHOOSE
              1   95717 2008-10-29 00:05:40 3487375171       177359624        223 CHOOSE
              1   95716 2008-10-28 23:45:40 3487375171       177359624        223 CHOOSE
              1   95715 2008-10-28 23:25:40 3487375171       177359624        223 CHOOSE
              1   95714 2008-10-28 23:05:40 3487375171       177359624        223 CHOOSE
              1   95703 2008-10-28 22:45:40 3487375171       177359624        223 CHOOSE
              1   95702 2008-10-28 22:25:40 3487375171       177359624        223 CHOOSE
              1   95701 2008-10-28 22:05:40 3487375171       177359624        223 CHOOSE
              1   95700 2008-10-28 21:45:40 3487375171       177359624        223 CHOOSE
              1   95699 2008-10-28 21:25:39 3487375171       177359624        223 CHOOSE
              1   95698 2008-10-28 21:05:40 3487375171       177359624        223 CHOOSE
              1   95697 2008-10-28 20:45:40 3487375171       177359624        223 CHOOSE
              1   95696 2008-10-28 20:25:40 3487375171       177359624        223 CHOOSE
              1   95695 2008-10-28 20:05:40 3487375171       177359624        223 CHOOSE
              1   95694 2008-10-28 19:45:40 3487375171       177359624        223 CHOOSE
              1   95683 2008-10-28 19:25:40 3487375171       177359624        223 CHOOSE
              1   95682 2008-10-28 19:05:40 3487375171       177359624        223 CHOOSE
              1   95681 2008-10-28 18:45:40 3487375171       177359624        223 CHOOSE
              1   95680 2008-10-28 18:25:41 3487375171       177359624        223 CHOOSE
              1   95679 2008-10-28 18:05:40 3487375171       177359624        223 CHOOSE
              1   95678 2008-10-28 17:45:39 3487375171       177359624        223 CHOOSE
              1   95677 2008-10-28 17:25:41 3487375171       177359624        223 CHOOSE
              1   95676 2008-10-28 17:05:40 3487375171       177359624        223 CHOOSE
              1   95664 2008-10-28 16:05:41 3487375171       177359624        223 CHOOSE
              1   95607 2008-10-28 12:25:40 3487375171       177359624        223 CHOOSE
              1   95606 2008-10-28 12:05:40 3487375171       177359624        223 CHOOSE
              1   95605 2008-10-28 11:45:39 3487375171       177359624        223 CHOOSE
 
-------------------------------------------  Instance 2 ------------------------------------
 
INSTANCE_NUMBER SNAP_ID SNAP_TIME           HASH_VALUE PLAN_HASH_VALUE       COST OPTIMIZER
--------------- ------- ------------------- ---------- --------------- ---------- ----------
              2   95954 2008-10-30 09:05:43 3487375171       378545151         28 CHOOSE
              2   95933 2008-10-30 08:45:43 3487375171       378545151         28 CHOOSE
              2   95932 2008-10-30 08:25:43 3487375171       378545151         28 CHOOSE
              2   95931 2008-10-30 08:05:43 3487375171       378545151         28 CHOOSE
              2   95930 2008-10-30 07:45:43 3487375171       378545151         28 CHOOSE
              2   95929 2008-10-30 07:25:43 3487375171       378545151         28 CHOOSE
              2   95928 2008-10-30 07:05:43 3487375171       378545151         28 CHOOSE
              2   95927 2008-10-30 06:45:43 3487375171       378545151         28 CHOOSE
              2   95926 2008-10-30 06:25:42 3487375171       378545151         28 CHOOSE
              2   95925 2008-10-30 06:05:42 3487375171       378545151         28 CHOOSE
              2   95924 2008-10-30 05:45:42 3487375171       378545151         28 CHOOSE
              2   95913 2008-10-30 05:25:43 3487375171       378545151         28 CHOOSE
              2   95912 2008-10-30 05:05:42 3487375171       378545151         28 CHOOSE
              2   95911 2008-10-30 04:45:43 3487375171       378545151         28 CHOOSE
              2   95910 2008-10-30 04:25:43 3487375171       378545151         28 CHOOSE
              2   95909 2008-10-30 04:05:42 3487375171       378545151         28 CHOOSE
              2   95908 2008-10-30 03:45:42 3487375171       378545151         28 CHOOSE
              2   95907 2008-10-30 03:25:42 3487375171       378545151         28 CHOOSE
              2   95906 2008-10-30 03:05:43 3487375171       378545151         28 CHOOSE
              2   95905 2008-10-30 02:45:42 3487375171       378545151         28 CHOOSE
              2   95904 2008-10-30 02:25:42 3487375171       378545151         28 CHOOSE
              2   95893 2008-10-30 02:05:42 3487375171       378545151         28 CHOOSE
              2   95892 2008-10-30 01:45:42 3487375171       378545151         28 CHOOSE
              2   95891 2008-10-30 01:25:42 3487375171       378545151         28 CHOOSE
              2   95890 2008-10-30 01:05:42 3487375171       378545151         28 CHOOSE
              2   95889 2008-10-30 00:45:43 3487375171       378545151         28 CHOOSE
              2   95888 2008-10-30 00:25:42 3487375171       378545151         28 CHOOSE
              2   95887 2008-10-30 00:05:43 3487375171       378545151         28 CHOOSE
              2   95886 2008-10-29 23:45:42 3487375171       378545151         28 CHOOSE
              2   95885 2008-10-29 23:25:42 3487375171       378545151         28 CHOOSE
              2   95873 2008-10-29 22:45:42 3487375171       177359624        223 CHOOSE
              2   95872 2008-10-29 22:25:41 3487375171       177359624        223 CHOOSE
              2   95871 2008-10-29 22:05:42 3487375171       177359624        223 CHOOSE
              2   95870 2008-10-29 21:45:42 3487375171       177359624        223 CHOOSE
              2   95869 2008-10-29 21:25:42 3487375171       177359624        223 CHOOSE
              2   95868 2008-10-29 21:05:42 3487375171       177359624        223 CHOOSE
              2   95867 2008-10-29 20:45:42 3487375171       177359624        223 CHOOSE
              2   95866 2008-10-29 20:25:42 3487375171       177359624        223 CHOOSE
              2   95865 2008-10-29 20:05:42 3487375171       177359624        223 CHOOSE
              2   95864 2008-10-29 19:45:42 3487375171       177359624        223 CHOOSE
              2   95853 2008-10-29 19:25:42 3487375171       177359624        223 CHOOSE
              2   95852 2008-10-29 19:05:41 3487375171       177359624        223 CHOOSE
              2   95851 2008-10-29 18:45:42 3487375171       177359624        223 CHOOSE
              2   95850 2008-10-29 18:25:42 3487375171       177359624        223 CHOOSE
              2   95849 2008-10-29 18:05:42 3487375171       177359624        223 CHOOSE
              2   95848 2008-10-29 17:45:41 3487375171       177359624        223 CHOOSE
              2   95847 2008-10-29 17:25:41 3487375171       177359624        223 CHOOSE
              2   95846 2008-10-29 17:05:42 3487375171       177359624        223 CHOOSE
              2   95845 2008-10-29 16:45:42 3487375171       177359624        223 CHOOSE
              2   95844 2008-10-29 16:25:42 3487375171       177359624        223 CHOOSE
              2   95830 2008-10-29 16:05:42 3487375171       177359624        223 CHOOSE
              2   95827 2008-10-29 15:05:42 3487375171       177359624        223 CHOOSE
              2   95826 2008-10-29 14:45:41 3487375171       177359624        223 CHOOSE
              2   95825 2008-10-29 14:25:41 3487375171       177359624        223 CHOOSE
              2   95824 2008-10-29 14:05:42 3487375171       177359624        223 CHOOSE
              2   95803 2008-10-29 13:45:41 3487375171       177359624        223 CHOOSE
              2   95802 2008-10-29 13:25:41 3487375171       177359624        223 CHOOSE
              2   95801 2008-10-29 13:05:42 3487375171       177359624        223 CHOOSE
              2   95800 2008-10-29 12:45:41 3487375171       177359624        223 CHOOSE
              2   95799 2008-10-29 12:25:41 3487375171       177359624        223 CHOOSE
              2   95798 2008-10-29 12:05:41 3487375171       177359624        223 CHOOSE
              2   95797 2008-10-29 11:45:41 3487375171       177359624        223 CHOOSE
              2   95796 2008-10-29 11:25:41 3487375171       177359624        223 CHOOSE
              2   95794 2008-10-29 10:45:42 3487375171       177359624        223 CHOOSE
              2   95787 2008-10-29 10:25:41 3487375171       177359624        223 CHOOSE
              2   95785 2008-10-29 09:45:41 3487375171       177359624        223 CHOOSE
              2   95771 2008-10-29 08:25:41 3487375171       177359624        223 CHOOSE
              2   95770 2008-10-29 08:05:41 3487375171       177359624        223 CHOOSE
              2   95769 2008-10-29 07:45:41 3487375171       177359624        223 CHOOSE
              2   95768 2008-10-29 07:25:41 3487375171       177359624        223 CHOOSE
              2   95767 2008-10-29 07:05:41 3487375171       177359624        223 CHOOSE
              2   95766 2008-10-29 06:45:41 3487375171       177359624        223 CHOOSE
              2   95765 2008-10-29 06:25:40 3487375171       177359624        223 CHOOSE
              2   95764 2008-10-29 06:05:41 3487375171       177359624        223 CHOOSE
              2   95753 2008-10-29 05:45:41 3487375171       177359624        223 CHOOSE
              2   95752 2008-10-29 05:25:41 3487375171       177359624        223 CHOOSE
              2   95751 2008-10-29 05:05:41 3487375171       177359624        223 CHOOSE
              2   95750 2008-10-29 04:45:40 3487375171       177359624        223 CHOOSE
              2   95749 2008-10-29 04:25:41 3487375171       177359624        223 CHOOSE
              2   95748 2008-10-29 04:05:40 3487375171       177359624        223 CHOOSE
              2   95747 2008-10-29 03:45:40 3487375171       177359624        223 CHOOSE
              2   95746 2008-10-29 03:25:41 3487375171       177359624        223 CHOOSE
              2   95745 2008-10-29 03:05:40 3487375171       177359624        223 CHOOSE
              2   95744 2008-10-29 02:45:41 3487375171       177359624        223 CHOOSE
              2   95733 2008-10-29 02:25:41 3487375171       177359624        223 CHOOSE
              2   95732 2008-10-29 02:05:40 3487375171       177359624        223 CHOOSE
              2   95731 2008-10-29 01:45:41 3487375171       177359624        223 CHOOSE
              2   95730 2008-10-29 01:25:40 3487375171       177359624        223 CHOOSE
              2   95729 2008-10-29 01:05:40 3487375171       177359624        223 CHOOSE
              2   95728 2008-10-29 00:45:41 3487375171       177359624        223 CHOOSE
              2   95727 2008-10-29 00:25:41 3487375171       177359624        223 CHOOSE
              2   95726 2008-10-29 00:05:40 3487375171       177359624        223 CHOOSE
              2   95725 2008-10-28 23:45:40 3487375171       177359624        223 CHOOSE
              2   95724 2008-10-28 23:25:40 3487375171       177359624        223 CHOOSE
              2   95713 2008-10-28 23:05:40 3487375171       177359624        223 CHOOSE
              2   95712 2008-10-28 22:45:40 3487375171       177359624        223 CHOOSE
              2   95711 2008-10-28 22:25:40 3487375171       177359624        223 CHOOSE
              2   95710 2008-10-28 22:05:40 3487375171       177359624        223 CHOOSE
              2   95709 2008-10-28 21:45:40 3487375171       177359624        223 CHOOSE
              2   95708 2008-10-28 21:25:39 3487375171       177359624        223 CHOOSE
              2   95707 2008-10-28 21:05:40 3487375171       177359624        223 CHOOSE
              2   95706 2008-10-28 20:45:40 3487375171       177359624        223 CHOOSE
              2   95705 2008-10-28 20:25:40 3487375171       177359624        223 CHOOSE
              2   95704 2008-10-28 20:05:40 3487375171       177359624        223 CHOOSE
              2   95693 2008-10-28 19:45:40 3487375171       177359624        223 CHOOSE
              2   95692 2008-10-28 19:25:40 3487375171       177359624        223 CHOOSE
              2   95691 2008-10-28 19:05:40 3487375171       177359624        223 CHOOSE
              2   95690 2008-10-28 18:45:40 3487375171       177359624        223 CHOOSE
              2   95689 2008-10-28 18:25:40 3487375171       177359624        223 CHOOSE
              2   95684 2008-10-28 16:45:40 3487375171       177359624        223 CHOOSE
              2   95656 2008-10-28 16:25:40 3487375171       177359624        223 CHOOSE
              2   95655 2008-10-28 16:05:41 3487375171       177359624        223 CHOOSE
              2   95602 2008-10-28 13:45:40 3487375171       177359624        223 CHOOSE
              2   95601 2008-10-28 13:25:40 3487375171       177359624        223 CHOOSE
              2   95600 2008-10-28 13:05:40 3487375171       177359624        223 CHOOSE
              2   95599 2008-10-28 12:45:40 3487375171       177359624        223 CHOOSE
              2   95598 2008-10-28 12:25:40 3487375171       177359624        223 CHOOSE
              2   95597 2008-10-28 12:05:40 3487375171       177359624        223 CHOOSE
              2   95596 2008-10-28 11:45:39 3487375171       177359624        223 CHOOSE
              2   95595 2008-10-28 11:25:40 3487375171       177359624        223 CHOOSE
              2   95594 2008-10-28 11:05:40 3487375171       177359624        223 CHOOSE
              2   95567 2008-10-28 10:45:39 3487375171       177359624        223 CHOOSE
可以看出，在2008-10-29 23:25左右时执行计划发生了改变。
查看历史执执行计划：（通过查询v$sql_plan，使用plan_hash_value）
 
[Execution Plan Information]
--------------------------------------------------------------------------------------------------
| Operation                                        | PHV/Object Name     |  Rows | Bytes| Cost   |
--------------------------------------------------------------------------------------------------
|00[00]SELECT STATEMENT                            |plan_hash_value 17735|       |      |    216 |
|01[01]SORT ORDER BY                               |                     |     1 |  207 |    216 |
|02[02] FILTER                                     |                     |       |      |        |
|03[03]  TABLE ACCESS BY INDEX ROWID               |SYS_FIELD_DESC       |     1 |   43 |      2 |
|04[04]   NESTED LOOPS                             |                     |     1 |  207 |    200 |
|05[05]    NESTED LOOPS OUTER                      |                     |     1 |  164 |    198 |
|06[06]     NESTED LOOPS                           |                     |     1 |  111 |    197 |
|07[07]      MERGE JOIN CARTESIAN                  |                     |     1 |   65 |      5 |
|08[08]       TABLE ACCESS FULL                    |SYS_FIELD_DESC       |     1 |   43 |      2 |
|09[08]       BUFFER SORT                          |                     |     1 |   22 |      3 |
|10[09]        TABLE ACCESS BY INDEX ROWID         |ACCT_75              |     1 |   22 |      3 |
|11[10]         INDEX RANGE SCAN                   |IDX_ACCT_CODE_75     |     1 |      |      2 |
|12[07]      TABLE ACCESS BY GLOBAL INDEX ROWID    |PT_75                |     1 |   46 |    192 |
|13[08]       INDEX RANGE SCAN                     |IDX_PT_75_ACCTI      |    11 |      |      2 |
|14[06]     VIEW PUSHED PREDICATE                  |                     |     9 |  477 |      1 |
|15[07]      NESTED LOOPS OUTER                    |                     |     1 |   53 |      7 |
|16[08]       NESTED LOOPS OUTER                   |                     |     1 |   38 |      6 |
|17[09]        NESTED LOOPS OUTER                  |                     |     1 |   26 |      4 |
|18[10]         TABLE ACCESS BY INDEX ROWID        |SYS_OPERATOR         |     1 |   14 |      2 |
|19[11]          INDEX UNIQUE SCAN                 |PK_SYS_OPERATOR      |     1 |      |      1 |
|20[10]         TABLE ACCESS BY INDEX ROWID        |PARTY_ROLE           |     1 |   12 |      2 |
|21[11]          INDEX RANGE SCAN                  |IDX_PARTYROLE_PARTY_ |     1 |      |      1 |
|22[09]        TABLE ACCESS BY INDEX ROWID         |PARTY_ROLE_RELAT     |     1 |   12 |      2 |
|23[10]         INDEX RANGE SCAN                   |IDX_PARTY2_ROLE_ID   |     1 |      |      1 |
|24[08]       TABLE ACCESS BY INDEX ROWID          |PARTY_ROLE           |     1 |   15 |      1 |
|25[09]        INDEX UNIQUE SCAN                   |PK_PARTY_ROLE        |     1 |      |        |
|26[05]    INDEX RANGE SCAN                        |SYS_FIELD_DESC_1     |     1 |      |      1 |
--------------------------------------------------------------------
通过对比前后执行计划，可以看出，之前的执行计划，走索引IDX_PT_75_ACCTI，而当前走索引IDX_PT_75_DAY。
通过查询dba_objects，发现IDX_PT_75_DAY正是10月29号23点创建的。因而导致了执行计划的改变。
 
SQL>SELECT owner, object_name, object_type, created, last_ddl_time, status
  2    FROM dba_objects
  3   WHERE object_name ='IDX_PT_75_DAY';
 
OWNER    OBJECT_NAME         OBJECT_TYPE  CREATED             LAST_DDL_TIME       STATUS
-------- ------------------- ------------ ------------------- ------------------- ------
PGATE    IDX_PT_75_DAY       INDEX        2008-10-29 23:05:22 2008-10-29 23:05:22 VALID
通知应用开发人员，开发人员DROP IDX_PT_75_DAY索引后，数据库恢复正常。
查看执行计划信息：
 
----------------------------------------------  Instance 1 ------------------------------------
 
INSTANCE_NUMBER    SNAP_ID SNAP_TIME           HASH_VALUE PLAN_HASH_VALUE       COST OPTIMIZER
--------------- ---------- ------------------- ---------- --------------- ---------- ----------
              1      95991 2008-10-30 12:25:43 3487375171       177359624        223 CHOOSE
              1      95990 2008-10-30 12:05:43 3487375171       177359624        223 CHOOSE
              1      95989 2008-10-30 11:45:43 3487375171       177359624        223 CHOOSE
              1      95985 2008-10-30 10:25:43 3487375171       177359624        223 CHOOSE
              1      95985 2008-10-30 10:25:43 3487375171       378545151         28 CHOOSE
----------------------------------------------  Instance 2 ------------------------------------
 
INSTANCE_NUMBER    SNAP_ID SNAP_TIME           HASH_VALUE PLAN_HASH_VALUE       COST OPTIMIZER
--------------- ---------- ------------------- ---------- --------------- ---------- ----------
              2      95983 2008-10-30 12:45:43 3487375171       177359624        223 CHOOSE
              2      95982 2008-10-30 12:25:43 3487375171       177359624        223 CHOOSE
              2      95981 2008-10-30 12:05:43 3487375171       177359624        223 CHOOSE
              2      95980 2008-10-30 11:45:43 3487375171       177359624        223 CHOOSE
              2      95977 2008-10-30 10:45:43 3487375171       177359624        223 CHOOSE
              2      95976 2008-10-30 10:25:43 3487375171       177359624        223 CHOOSE
              2      95976 2008-10-30 10:25:43 3487375171       378545151         28 CHOOSE
执行计划已恢复正常。
查看当前执行计划：
 
[Execution Plan Information]
 
--------------------------------------------------------------------------------------------------
| Operation                                        | PHV/Object Name     |  Rows | Bytes| Cost   |
--------------------------------------------------------------------------------------------------
|00[00]SELECT STATEMENT                            |---- 3487375171.0 ---|       |      |    223 |
|01[01]SORT ORDER BY                               |                     |     1 |  218 |    223 |
|02[02] FILTER                                     |                     |       |      |        |
|03[03]  TABLE ACCESS BY INDEX ROWID               |SYS_FIELD_DESC       |     1 |   43 |      2 |
|04[04]   NESTED LOOPS                             |                     |     1 |  218 |    207 |
|05[05]    NESTED LOOPS OUTER                      |                     |     1 |  175 |    205 |
|06[06]     NESTED LOOPS                           |                     |     1 |  117 |    204 |
|07[07]      MERGE JOIN CARTESIAN                  |                     |     1 |   65 |      6 |
|08[08]       TABLE ACCESS FULL                    |SYS_FIELD_DESC       |     1 |   43 |      2 |
|09[08]       BUFFER SORT                          |                     |     1 |   22 |      4 |
|10[09]        TABLE ACCESS BY INDEX ROWID         |ACCT_75              |     1 |   22 |      4 |
|11[10]         INDEX RANGE SCAN                   |IDX_ACCT_CODE_75     |     1 |      |      2 |
|12[07]      TABLE ACCESS BY GLOBAL INDEX ROWID    |PT_75                |     1 |   52 |    198 |
|13[08]       INDEX RANGE SCAN                     |IDX_PT_75_ACCTI      |    11 |      |      2 |
|14[06]     VIEW PUSHED PREDICATE                  |                     |    10 |  580 |      1 |
|15[07]      NESTED LOOPS OUTER                    |                     |     1 |   58 |      7 |
|16[08]       NESTED LOOPS OUTER                   |                     |     1 |   42 |      6 |
|17[09]        NESTED LOOPS OUTER                  |                     |     1 |   29 |      4 |
|18[10]         TABLE ACCESS BY INDEX ROWID        |SYS_OPERATOR         |     1 |   15 |      2 |
|19[11]          INDEX UNIQUE SCAN                 |PK_SYS_OPERATOR      |     1 |      |      1 |
|20[10]         TABLE ACCESS BY INDEX ROWID        |PARTY_ROLE           |     1 |   14 |      2 |
|21[11]          INDEX RANGE SCAN                  |IDX_PARTYROLE_PARTY_ |     1 |      |      1 |
|22[09]        TABLE ACCESS BY INDEX ROWID         |PARTY_ROLE_RELAT     |     1 |   13 |      2 |
|23[10]         INDEX RANGE SCAN                   |IDX_PARTY2_ROLE_ID   |     1 |      |      1 |
|24[08]       TABLE ACCESS BY INDEX ROWID          |PARTY_ROLE           |     1 |   16 |      1 |
|25[09]        INDEX UNIQUE SCAN                   |PK_PARTY_ROLE        |     1 |      |        |
|26[05]    INDEX RANGE SCAN                        |SYS_FIELD_DESC_1     |     1 |      |      1 |
--------------------------------------------------------------------
 
[Predicate Information]
 
--------------------------------------------------------------------
 
         2 filter::2< =:3
         3 filter:"A"."PAYED_METHOD"="D"."VALUE"
         8 filter:"C"."TABLE_NAME"='PT' AND "C"."COLUMN_NAME"='CERTIFICATE_T
           YPE'
 
        11 access:"B"."ACCT_CODE"=:1
        12 filter:"A"."AMOUNT"<>0 AND "A"."CERTIFICATE_TYPE"="C"."VALUE" AND TO_C
           HAR("A"."PAY_DATE",'yyyymmdd')>=:2 AND TO_CHAR("A"."PAY_DATE",'yyyymmd
           d')< =:3
 
        13 access:"A"."ACCT_ID"="B"."ACCT_ID"
        18 filter:NVL("X"."REGION_ID",0)=75 OR NVL("X"."REGION_ID",0)=0
        19 access:"A"."STAFF_ID"="X"."OPERATOR_ID"
        21 access:"X"."PARTY_ID"="Y"."PARTY_ID"(+)
        23 access:"Y"."PARTY_ROLE_ID"="Z"."PARTY2_ROLE_ID"(+)
        25 access:"Z"."PARTY1_ROLE_ID"="O"."PARTY_ROLE_ID"(+)
        26 access:"D"."TABLE_NAME"='PT_PLAN' AND "D"."COLUMN_NAME"='PT_
           METHOD'

来自 “ ITPUB博客 ” ，链接：http://blog.itpub.net/22578826/viewspace-741756/，如需转载，请注明出处，否则将追究法律责任。

转载于:http://blog.itpub.net/22578826/viewspace-741756/

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