This is one of the technical infrastructure data gathering methodologies and performance recommendations for server machines. The full list is defined in the Server Environment Recommendations topic here.
Oracle version 12.1.0.2. includes a known issue (bug) in which a 'directive' is used. For some queries, this means a poor execution plan, and response times go from milliseconds to seconds.
This has quite an unfortunate impact on performance, and when displaying execution plans for SQL queries, shows up as an 'adaptive plan' by Oracle.
Recommendation
- In Oracle version 12.1.0.2, the parameter should be set to FALSE.
- Once Oracle is upgraded to 12.2.0.1 or greater, reassess the parameter setting.