Oracle library access is slow. Why?

Oracle Library access is slow , What is the reason ？

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Take the answer 1：

Provide a simple idea ：

1、 Is the whole library slow or part of the application slow ？

2、 Is the database level slow or the system level slow ？

If the whole library is slow , By analyzing the use of server resources and whether there are locks at the database level 、 jam 、 Abnormal waiting events are analyzed .

If some applications are slow , Other applications are normal , By analyzing SQL To optimize .

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Other answers 1：

Provide a simple idea ：

1、 Is the whole library slow or part of the application slow ？

2、 Is the database level slow or the system level slow ？

If the whole library is slow , By analyzing the use of server resources and whether there are locks at the database level 、 jam 、 Abnormal waiting events are analyzed .

If some applications are slow , Other applications are normal , By analyzing SQL To optimize .

Other answers 2：

Your question , It's too general . Is there any specific phenomenon , Or logs

Other answers 3：

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Other answers 4：

      1、 No index or no index used ( This is the most common problem with slow queries , It's a programming flaw )
　　
　　2、I/O Small throughput , It's a bottleneck effect .
　　
　　3、 The query is not optimized because the computed column is not created .
　　
　　4、 Out of memory
　　
　　5、 The Internet is slow
　　
　　6、 The amount of data found is too large （ You can use multiple queries , Other ways to reduce the amount of data ）
　　
　　7、 Lock or deadlock ( This is also the most common problem of slow query , It's a programming flaw )
　　
　　8、sp_lock,sp_who, Active users view , The reason is that literacy competes for resources .
　　
　　9、 Returns unnecessary rows and columns
　　
　　10、 The query statement is not good , No optimization

Check it out

Other answers 5：

It is usually a load problem . Look at the corresponding AWR, Look at the .

Other answers 6：

1、 Is it slow to establish links ？----》 Possible network problems , System resource problems ,DNS Analytical problem

2、 database SQL Slow execution ？

     a、 Single sql slow ----》 Need to view this sql Implementation of the plan , Whether the implementation plan changes , Whether the statistical information is accurate , Abnormal waiting time .

     b、 All slow   -----》 Whether the database has session congestion , Row lock , Exception wait event .