操作FILTER 的优化

SQL> explain plan for select * from emp where job='CLERK' and 1=2;

 

SQL> select * from table(dbms_xplan.display);

 

0  SELECT STATEMENT

*1 FILTER

2    TABLE ACCESS BY INDEX ROWID

*3     INDEX RANGE SCAN

 

 

1-filter(NULL IS NOT NULL)

3-access("JOB"='CLERK')