SPM Auto Load Capture and Use.

Question

Hi,
I was reading about Oracle SPM feature, but i have questions in mind for automatic feature..
* if we have set both capture and use parameter true. Oracle will automatically capture Plans, but will it automatically evolve new plans to accepted or it will wait for evolve it manually before using new plan.
* If it Automatically evolve, when and how will it?
* If it Automatically, will change old plan's flag accepted to No? or add one more accepted plan
regards
Hitesh

Answer 1

if we have set both capture and use parameter true. Oracle will automatically capture PlansCorrect.
but will it automatically evolve new plans to accepted or it will wait for evolve it manually before using new plan.For plans manually loaded into a baseline, these should be loaded as accepted.
If a plan is loaded automatically and no plan already exists, then the first plan will be created as ACCEPTED=YES.
Otherwise, if the plans are loaded automatically, then they will not be accepted until performance has been verified by the evolution process.
If it Automatically evolve, when and how will it?If the task is enabled, the SQL Tuning Advisor auto task will deal with the automatic evolution.
If it Automatically, will change old plan's flag accepted to No? or add one more accepted planThe accepted flag of the previous plan should not be set to NO, there should be multiple accepted plans.
It might be worth taking a step back and looking at the big picture with automatic baseline capture on.
- If you have a SQL statement for which there is not an accepted baseline, on parse the optimizer does its usual optimizer business and the generated plan is stored in a baseline as ACCEPTED=YES.
- If you have a SQL statement for which there is already an accepted baseline, on parse the optimizer does its usual optimizer business.
- If the plan it comes up with by default matches one of the baselines, great.
- If the plan doesn't match one of the baselines then it will store the generated plan in the baseline to wait for evolution.
- The optimizer will then use the outline hints in the baseline to generate the particular plan - to do this it has to match the plan_hash_2 value to the underlying plan id in sys.sqlobj$/sqlobj$data/sqlobj$auxdata.
- If the optimizer can generate the plan, great.
- If the optimizer cannot generate the baselined plan, then it will revert to the generated plan and mark the relevant plan as reproduced=NO.
- What if there are multiple accepted plans? It will attempt to reproduce the plans in order of lowest cost baselined plans first.