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使用eventapi診斷數據導入imp性能

2013-11-13 22:07:49  來源: Oracle 

  SQL> select eventTOTAL_WAITS TIME_WAITEDAVERAGE_WAIT from  v$session_event where sid= order by TIME_WAITED desc;

  EVENT                                                            TOTAL_WAITS

TIME_WAITED AVERAGE_WAIT

db file sequential read                                            
      

  free buffer waits                                                    
       

  log file switch completion                                            
       

  EVENT                                                            TOTAL_WAITS

TIME_WAITED AVERAGE_WAIT

log file sync                                                        
       

  SQL*Net message from client                                            
        

  latch free                                                            
        

  EVENT                                                            TOTAL_WAITS

TIME_WAITED AVERAGE_WAIT

log file switch (checkpoint incomplete)                                
        

  SQL*Net more data from client                                       
        

  enqueue                                                                
        

  EVENT                                                            TOTAL_WAITS

TIME_WAITED AVERAGE_WAIT

undo segment extension                                              
        

  write complete waits                                                    
          

  buffer busy waits                                                    
         

  EVENT                                                            TOTAL_WAITS

TIME_WAITED AVERAGE_WAIT

SQL*Net message to client                                              
            

  file open                                                                
            

  發現db file sequential read 居高通常在單塊讀發生該事件用於索引讀取察看正在導入數據的表果然索引俱全導入數據的時候要維護索引對每個導入的數據都要找到對應的索引葉結點插入新索引enry 刪除索引後該等待事件降低

  通常如果發生較高的log file sync  事件表示導入進程提交過於頻繁增加buffer參數可以減少commit次數減少該等待事件


From:http://tw.wingwit.com/Article/program/Oracle/201311/18307.html
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