| Since database become the most useful management way of data, it has developed and perfected rapidly to the direction that the data structure is more and more complex, the amount of data becomes larger and larger and the application becomes wider and wider. The tight relationship and fusion with the application system makes the users improve the requirement of it performance, especially in the database with a mass mount of data. Besides the limit of software and hardware, the efficiency of inquiring statement becomes the key factor in the performance. The running SQL statement consumes most of the resource of database, so it is necessary to adjust it and it makes sense to improve the performance of the database.This paper researches and analyses the execution procedure and mechanism of Oracle database, and learns the way of handling the SQL statement and the factor of affecting the execution plan. Then the paper makes it be the theory source of the optimization rule. The paper puts forward optimization rules of SQL statement based on the optimization target in Oracle database. The rules contain the ones that has been already exist, the new ones raised by this paper and the wrong ones that known by people, at the same time it analyzes the reason of the rule.What also included in the research is that Oracle database storages the message analyzed and executed, and by this message the low quality SQL statement executed in the system can be found. Meanwhile it diagnoses and checks up the performance problem of executed SQL statement and raises optimization advisement.The main achievement and creativity of this paper are acquiring the optimization rule of Oracle database, and in the way of calling Oracle order and designing a plan to judge the validity of optimization rule. At the same time the low quality SQL statement in the Oracle database can be acquired directly, and at the last the performance of the SQL statement can be diagnosed automatically followed with optimization advisement. |
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