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1 Overview The nature of the SQL language is a string of pseudo code that expresses what to do rather than what to do. As in other languages, SQL statements need to be compiled before they can be run, so every SQL needs to be interpreted by the compiler to run (and also to optimize SQL). These steps require running costs, so there is something called an execution plan in the database, and the compiler will store the compiled SQL in the execution

Tags: parameter sniffThe parameter sniff problem is to reuse the execution plan generated by other parameters, leading to the non-optimization of the execution plan by the current parameters. Presumably familiar with the data of the students should know that the most typical problem of producing parameter sniff is the use of parameterized SQL (or stored procedures using parameterized), if there is uneven di

Label:Prior to the 11g version, the stored outlines (SQL Profile) feature was provided to save the SQL execution plan. In 11g, a new feature SQL plan management (SQL Management) feature was introduced to save SQL performance. The database automatically controls the evolution of the SQL execution plan, with SQL plan ba

I. Overview Performance risks may occur when the SQL Execution Plan of an SQL statement is changed. There are many reasons for changing the SQL plan, such as the Optimized Program version, optimized program statistics, optimized program parameters, solution definition, system design, and SQL profile creation. In earlier versions of Oracle DB, various plan control

everything in the world begins with a plan. The success of one thing must also have a comprehensive plan. To achieve great success, we need to set different milestones to achieve the ultimate goal. To do a good job, we also need to know when to do what to do. A plan is always bound to a task. It is a prelude to the beginning of the implementation cycle of the ent

Tags: div flush condition Statement deployment put where count off1. Get an execution plan for SQL in PL developerEnter the target SQL for which you want to view the execution plan, and then press the shortcut key F5.2.explain Plan CommandExplain plan for + target SQLSELECT * FROM table (Dbms_xplan.display)3. Dbms_xpla

Test Plan Evaluation ModelChen nengji-8-12 original article: Test Plan Evaluation Model-James Bach, to answer "is the test plan determined ?" To answer this question, we need to answer the test plan. Although there are many test plan document templates, they do not distingui

Plan Name:SOrigin"Read s planS can represent "books", "History", and "Specification ". I initially wanted to name this idea "the historical Reading Plan", but the "History" sound is the same as "shit". It sounds indecent and it is easy to think of people as reading Chinese classical classics, for example, historical records and four databases lack the characteristics of the IT industry. Then I want to chang

The method for generating and displaying execution plans in Oracle. In addition to the executed SQL statements, the execution plan is generated in the memory, and the explain Plan can be used to enable the optimizer to parse the SQL statements, The method for generating and displaying execution plans in Oracle. In addition to the executed SQL statements, the execution p