Use of the 1.explain plan
sql> explain plan for delete from T_jingyu; Explained.sql> select * FROM table (dbms_xplan.display); Plan_table_ OUTPUT------------------------------------------------------------------------------------------------------------------- -------------------------Plan Hash value:1368587462------------------------------------------------------------- ----------| Id | Operation | Name | Rows | Cost (%CPU) | Time |-----------------------------------------------------------------------| 0 | DELETE STATEMENT | | 1864k| 978 (2) | 00:00:12 | | 1 | DELETE | T_jingyu | | | || 2 | TABLE ACCESS full| T_jingyu | 1864k| 978 (2) | 00:00:12 |-----------------------------------------------------------------------Note------Dynamic sampling used For this statement (level=2) rows selected
2.explain plan simply shows the execution plan and does not actually execute the DELETE statement ·
Sql> Select COUNT (*) from T_jingyu; COUNT (*)---------- 2097152
SQL Tuning Basics Overview of the use of 02-explain plan