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12c Hybrid Hash Distribution with Skew Detection / Handling

Oracle 12c introduces several new features in the area of Parallel Execution. Over the next couple of weeks I attempt to publish more about them - Jonathan Lewis for example already published a note about the new "PQ Replication" feature that applies to the BROADCAST distribution of small tables.One important new feature is the automatic skew handling for parallel joins. I've already given an overview of the feature in my mini-series "Parallel Execution Skew" at "", so if all you want is a high-level overview I recommend reading the article there.The purpose of this note here is to provide a few more internals and details about that feature.First, just a short summary of the prerequisites of the feature to work:1.