Oracle parallel query hints - part 1: PQ_DISTRIBUTE
![](https://www.pythian.com/hubfs/Imported_Blog_Media/PQ_DISTRIBUTE.png)
One of the most powerful features of the Oracle database is its ability to leverage multiple cores spread across many RAC servers to execute a single query. Oracle's optimizer tries its best to execute queries in the most efficient manner, but often the best distribution of data is not obvious from the statistics alone - and some hints are needed to help out. The most important hint is PQ_DISTRIBUTE, but it's also the most tricky to use as it depends on so many other hints. The Oracle documentation offers the bare minimum on usage, and there are no "Oracle Support" articles that help. For something so complex and important, it's a rather big miss from Oracle. There should be examples, use cases etc. But then again .. Microsoft's SQL Server is not any better in describing control nobs for parallel query executions. So we have to rely on the community for those. Let's start with basics (from the docs):
![](https://www.pythian.com/hs-fs/hubfs/Imported_Blog_Media/PQ_DISTRIBUTE.png?width=776&height=65&name=PQ_DISTRIBUTE.png)
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