Insights into Statistics, Query Optimization and the Oracle Optimizer

Hint Reporting in Oracle Database 19c

Nigel Bayliss
Product Manager

I mentioned in an earlier blog post that in Oracle Database 19c we introduced a hint usage report for DBMS_XPLAN. If you have been using this feature then you might have noticed that some hints are not reported. We can loosely categorize them as execution hints, and this is a known limitation of the hint usage report. The ones you are most likely to notice are perhaps APPEND, BIND_AWARE and GATHER_OPTIMIZER_STATISTICS. There are some inconsistencies in the reporting of parallel execution hints too.

This is the subject of an enhancement request - number 29319971. Currently the ER is not published, but I want you to be aware that it is in the system.


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