oracle addm segment tuning

   最近客戶出現一次，資料庫效能問題，業務訪問某個表時，非常慢，後來檢視addm報告，

 

建議對這個表重建，重建後恢復正常。 可能是這個表產生碎片太多。

 

 Recommendation 1: Segment Tuning
   Estimated benefit is 354.08 active sessions, 100% of total activity.
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   Action
      Run "Segment Advisor" on TABLE PARTITION
      "DB.OPINION_INST.00000" with object ID 66801.
      Related Object
         Database object with ID 66801.
   Action
      Investigate application logic involving I/O on TABLE PARTITION
      "DB_EXOA.MV_OPINION_INST.DC_WFOI500000" with object ID 66801.
      Related Object
         Database object with ID 66801.
   Action
      Look at the "Top SQL Statements" finding for SQL statements consuming
      significant I/O on this segment. For example, the SELECT statement with
      SQL_ID "4sfsdc5cxbb9t" is responsible for 28% of "User I/O" and
      "Cluster" waits for this segment.
   Rationale
      The I/O usage statistics for the object are: 823 full object scans,
      106338050 physical reads, 5 physical writes and 106337547 direct reads.