spark-reviews mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From GitBox <...@apache.org>
Subject [GitHub] [spark] cloud-fan commented on a change in pull request #27616: [SPARK-30864] [SQL]add the user guide for Adaptive Query Execution
Date Thu, 12 Mar 2020 07:32:40 GMT
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_r391441866
 
 

 ##########
 File path: docs/sql-performance-tuning.md
 ##########
 @@ -186,3 +186,61 @@ 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 makes 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. As of Spark 3.0, there are three major features in AQE, including
coalescing post-shuffle partitions, local shuffle reader optimization and skewed join optimization.
+ ### Coalescing Post Shuffle Partition Number
+ This feature coalesces the post shuffle partitions based on the map output statistics when
`spark.sql.adaptive.enabled` and `spark.sql.adaptive.coalescePartitions.enabled` configuration
properties are both enabled. There are four following sub-configurations in this optimization
rule. This feature simplifies the tuning of shuffle partitions number when running queries.
You don't need to set a proper shuffle partition number to fit your dataset. You just need
to set a large enough number and Spark can pick the proper shuffle partition number at runtime.
 
 Review comment:
   `You just need to set a large enough number` -> `You just need to set a large enough
initial number of shuffle partitions via xxx config, and ...`

----------------------------------------------------------------
This is an automated message from the Apache Git Service.
To respond to the message, please log on to GitHub and use the
URL above to go to the specific comment.
 
For queries about this service, please contact Infrastructure at:
users@infra.apache.org


With regards,
Apache Git Services

---------------------------------------------------------------------
To unsubscribe, e-mail: reviews-unsubscribe@spark.apache.org
For additional commands, e-mail: reviews-help@spark.apache.org


Mime
View raw message