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This finding may appear when the difference between the best and worse plans, within a selected time frame, is significant in terms of in Oracle time. This indicates that some plans were used, and the best plan consumed significantly less resources of Oracle than the worse plan.
| Significant differentiation between best and worse plans |
| Description | |
| What to do next | Perform one of the following options: n Compare the execution plan of the best plan with the execution plan of the worse plan (also includes a comparison of costs). In the Bind variables tab, check if the difference can be attributed to using a different bind set. If not, check if the significant difference can be derived from a change of one of the objects. n If you find that the difference between the best and worse plans is derived from a different bind set, consider running the statement using a different bind set and compare their run times. |
| Advice | If the significant difference between the best and worse plans was derived from using a different bind set consider: n Fixing an optimal plan using outlines or profiles. n Disabling bind peeking by setting the "_optim_peek_user_binds" parameter to FALSE. n Using literals instead of bind variables. If the significant difference between the best and worse plans were derived from a change of one of the objects within the plan: n Explore the objects that are being accessed inefficiently in the worst plan, in the Objects workspace. Check if the table grew significantly or if one of the indexes was dropped and can be rebuilt. n Consider using outlines or profiles for checking improvements to the worst plan. Note: Notice that setting the "_optim_peek_user_binds" parameter to FALSE will influence all statements running in this instance. |
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