cloud-fan commented on a change in pull request #27616: [SPARK-30864] [SQL]add
the user guide for Adaptive Query Execution
URL: https://github.com/apache/spark/pull/27616#discussion_r380469743
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File path: docs/sql-performance-tuning.md
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@@ -186,3 +186,75 @@ The "REPARTITION_BY_RANGE" hint must have column names
and a partition number is
SELECT /*+ REPARTITION(3, c) */ * FROM t
SELECT /*+ REPARTITION_BY_RANGE(c) */ * FROM t
SELECT /*+ REPARTITION_BY_RANGE(3, c) */ * FROM t
+
+## Adaptive Query Execution
+Adaptive Query Execution (AQE) is an optimization technique in Spark SQL that
make use of the runtime statistics to choose the most efficient query execution
plan. AQE is disabled by default. Spark SQL can use the umbrella configuration
of `spark.sql.adaptive.enabled` to control whether turn it on/off. There are
three mainly feature in AQE, including coalescing post partition number,
optimizing local shuffle reader and optimizing skewed join.
Review comment:
post-shuffle partition number
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