I’m refreshing our Hands-On Lab for Oracle Database 18c. And as part of a performance evaluation I wanted to set an underscore parameter to ignore all hints my load test tool sets. But then I learned: This does not work anymore as _optimizer_ignore_hints is now optimizer_ignore_hints. We made the underscore obsolete in Oracle Database 18c. _optimizer_ignore_hints is now optimizer_ignore_hints Actually in Oracle Database 12.2.0.1 you can find a long list of obsolete parameters here: Obsolete Parameters in Oracle Database 12.2.0.1 (Nov 10, 2016) To be precise: We obsoleted159 parameters. In addition, in Oracle Database 18c we added an additional 8 … Continue reading _optimizer_ignore_hints is now optimizer_ignore_hints