View the Exhibit exhibit1 to examine the series of SQL commands and parameter settings.
View the Exhibit exhibit2 to examine the plans available in the SQL plan baseline.
The first plan (in red) is created when OPTIMIZER_MODE is set to ALL_ROWS and the second
plan (in blue) is created when OPTIMIZER_MODE is set to FIRST_ROWS.
Which SQL plan baseline would be used if the SQL query in exhibit1 is executed again when the value of
OPTIMIZER_MODE is set to FIRST_ROWS?
A.
the second plan, because it is a fixed plan
B.
the first plan, because it is an accepted plan
C.
the second plan, because it is the latest generated plan in FIRST_ROW mode
D.
A new plan, because the second plan in FIRST_ROW mode is not an accepted plan
A is correct
when there is a fixed plan, optimizer uses it.
A is correct.
SQL plan management (SPM) ensures that runtime performance will never degrade due to the
change of an execution plan. To guarantee this, only accepted (trusted) execution plans will be
used; any plan evolution will be tracked and evaluated at a later point in time and only be
accepted as verified if the new plan causes no runtime change or an improvement of the runtime.
Guess you are the retard
If a fixed SQL plan baseline also contains non-fixed plans, then the optimizer gives preference to fixed plans over non-fixed ones.
b is the correct answer because red plan is the accepted plan,fixed means it fixes the plan for the query
b is the correct answer because red plan is the accepted plan whereas the blue one is not the accepted plan,fixed means it fixes the plan for the query
https://avdeo.com/2011/06/07/oracle-sql-plan-management-%E2%80%93-part-2/