STATISTICS COLLECTOR
STATISTICS COLLECTOR indicates the optimizer is using an ADAPTIVE query plan and gathering stats during the query execution
Detailed Description​
STATISTICS COLLECTOR indicates the optimizer is using an ADAPTIVE query plan and gathering stats during the query execution. When the initialization parameter STATISTICS_LEVEL is set to ALL Oracle will collect statistics during the execution of the query in order to find the best plan. This differs from the TYPICAL statistics level where the optimizer updates itself after the first execution and only picks the optimal plan on the second and subsequent execution.
ADAPTIVE query plans will be indicated in the Notes section of the plan.
There will be steps in these plans that have been evaluated, but not used. These will be indicated with a leading hyphen ‘-’.
Further Reading​
- Oracle Tuning Guide - Explaining Adaptive Query Plans: Tutorial
- Oracle Reference - initialization parameter STATISTICS_LEVEL
- Oracle Magazine - How to read an execution plan
- Oracle Tuning Guide - Explaining and Displaying Execution Plans
- Oracle Tuning Guide - Comparing Execution Plans Tutorial
Search online​
If this article doesn't have the information you need you can try searching online. Remember, you can contribute suggestions to this page.