Oracle Database Administration

Deal all, Below post content is not my own. It is taken from MOSC document but the example shown below is taken from our environment. I got to know the below topic when we had experienced the bad SQL query performance in one of our production environment during daily batch running time. Hence we had implemented the same mentioned in the title "Pinning execution plan for a sql_id using 'SQL Profile' to consistently reproduce a good plan". Introduction The "cost-based optimizer (CBO or just optimizer) is the part of database software that determines the most efficient means of accessing the specified data (or at least what it "calculates" as the most efficient). The optimizer determines which execution plan is most efficient by considering several sources of information, including query conditions, available access paths, statistics gathered for the system, and hints. Some changes in those conditions may affect the calculations of the plan