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https://issues.apache.org/jira/browse/SPARK-20107?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16073951#comment-16073951
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Steve Loughran commented on SPARK-20107:
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If you are curious, I've just written out the v1 and v2 commit algorithms with
cost/complexity estimates:
https://github.com/steveloughran/hadoop/blob/s3guard/HADOOP-13786-committer/hadoop-tools/hadoop-aws/src/site/markdown/tools/hadoop-aws/s3a_committer_architecture.md
> Add spark.hadoop.mapreduce.fileoutputcommitter.algorithm.version option to
> configuration.md
> -------------------------------------------------------------------------------------------
>
> Key: SPARK-20107
> URL: https://issues.apache.org/jira/browse/SPARK-20107
> Project: Spark
> Issue Type: Improvement
> Components: Documentation
> Affects Versions: 2.1.0
> Reporter: Yuming Wang
> Assignee: Yuming Wang
> Priority: Trivial
> Fix For: 2.2.0
>
>
> Set {{spark.hadoop.mapreduce.fileoutputcommitter.algorithm.version=2}} can
> speed up
> [HadoopMapReduceCommitProtocol#commitJob|https://github.com/apache/spark/blob/v2.1.0/core/src/main/scala/org/apache/spark/internal/io/HadoopMapReduceCommitProtocol.scala#L121]
> for many output files.
> It can speed up {{11 minutes}} for 216869 output files:
> {code:sql}
> CREATE TABLE tmp.spark_20107 AS SELECT
> category_id,
> product_id,
> track_id,
> concat(
> substr(ds, 3, 2),
> substr(ds, 6, 2),
> substr(ds, 9, 2)
> ) shortDate,
> CASE WHEN actiontype = '0' THEN 'browse' WHEN actiontype = '1' THEN 'fav'
> WHEN actiontype = '2' THEN 'cart' WHEN actiontype = '3' THEN 'order' ELSE
> 'invalid actio' END AS type
> FROM
> tmp.user_action
> WHERE
> ds > date_sub('2017-01-23', 730)
> AND actiontype IN ('0','1','2','3');
> {code}
> {code}
> $ hadoop fs -ls /user/hive/warehouse/tmp.db/spark_20107 | wc -l
> 216870
> {code}
> We should add this option to
> [configuration.md|http://spark.apache.org/docs/latest/configuration.html].
> All cloudera's hadoop 2.6.0-cdh5.4.0 or higher versions(see:
> [cloudera/hadoop-common@1c12361|https://github.com/cloudera/hadoop-common/commit/1c1236182304d4075276c00c4592358f428bc433]
> and
> [cloudera/hadoop-common@16b2de2|https://github.com/cloudera/hadoop-common/commit/16b2de27321db7ce2395c08baccfdec5562017f0])
> and apache's hadoop 2.7.0 or higher versions support this improvement.
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