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Home -> Community -> Usenet -> c.d.o.misc -> why oracle does not use pk_emp in my select?
i exec following sql in scott/tiger:
"explain plan for select empno from emp"
but it shows
| 0 | SELECT STATEMENT | | 82 | 1066 | 2 | | 1 | TABLE ACCESS FULL | EMP | 82 | 1066 | 2 |Note: cpu costing is off
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why doesn't it perform full index scan since pk_emp contain the empno
needed!
by the way, what 's meaning of "Note: cpu costing is off"?????
i am a freshman, thks! Received on Wed Mar 26 2003 - 21:36:37 CST