To master the SQL tuning technology, you need to be able to understand the execution plan of the SQL statement. To understand the execution plan of the SQL statement, you not only need to accurately understand the operations and meanings in the SQL statement execution plan, but also need to accurately understand the execution of the SQL statement. The meaning of each data item in the plan. In Chapter 7 of this book, the meaning of each operation in the SQL statement execution plan has been explained in detail. In this chapter, we will give a detailed description and explanation of the common data items in the SQL statement execution plan.
8.1. Execution plan data items
In daily tuning work, the most common way to obtain the SQL statement execution plan is through the "explain plan for" command. This method has been favored by many for its simplicity, convenience, professionalism, rich information, and almost no impact on the server. It is favored and preferred by professionals. Below, each data item in the SQL statement execution plan obtained through this method will be described and explained in detail, so that readers can correctly understand the exact meaning of each data item. An example of an SQL statement execution plan is shown in Figure 8.1-1.
Figure 8.1-1 Example of SQL statement execution plan
--Note:
1) Plan hash va