We all know adaptive query feature introduced in Oracle Database Release 1 is a problem. Recently I had the opportunity to review few 12cR1 databases and found that to alleviate the performance problems, the DBA set parameter OPTIMIZER_FEATURES_ENABLE=11.2.0.4 in Oracle Database 12c Release 1 (12.1.0.2). This observation is the catalyst for the blog “Adaptive Query Patches in Oracle Database 12c Release 1” on my Company Blog. Oracle Support team provided options to turn off the new feature (OPTIMIZER_ADAPTIVE_FEATURES=FALSE) or to fix the issues with a Proactive Bundle Patch or with a one-off patch. Please read the blog to find out the options DBA have to fix the adaptive query optimization problem in Oracle Database 12c Release 1.
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