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Posted to issues@spark.apache.org by "John Zhuge (JIRA)" <ji...@apache.org> on 2018/07/26 23:56:00 UTC
[jira] [Updated] (SPARK-24940) Coalesce Hint for SQL
[ https://issues.apache.org/jira/browse/SPARK-24940?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
John Zhuge updated SPARK-24940:
-------------------------------
Description:
Many Spark SQL users in my company have asked for a way to control the number of output files in Spark SQL. The users prefer not to use function repartition\(n\) or coalesce(n, shuffle) that require them to write and deploy Scala/Java/Python code.
There are use cases to either reduce or increase the number.
The DataFrame API has repartition/coalesce for a long time. However, we do not have an equivalent functionality in SQL queries. We propose adding the following Hive-style Coalesce hint to Spark SQL.
{noformat}
/*+ COALESCE(n, shuffle) */
/*+ REPARTITION(n) */
{noformat}
REPARTITION\(n\) is equal to COALESCE(n, shuffle=true).
was:
Many Spark SQL users in my company have asked for a way to control the number of output files in Spark SQL. The users prefer not to use function repartition(n) or coalesce(n, shuffle) that require them to write and deploy Scala/Java/Python code.
There are use cases to either reduce or increase the number.
The DataFrame API has repartition/coalesce for a long time. However, we do not have an equivalent functionality in SQL queries. We propose adding the following Hive-style Coalesce hint to Spark SQL.
{noformat}
/*+ COALESCE(n, shuffle) */
/*+ REPARTITION(n) */
{noformat}
REPARTITION(n) is equal to COALESCE(n, shuffle=true).
> Coalesce Hint for SQL
> ---------------------
>
> Key: SPARK-24940
> URL: https://issues.apache.org/jira/browse/SPARK-24940
> Project: Spark
> Issue Type: Improvement
> Components: SQL
> Affects Versions: 2.1.1
> Reporter: John Zhuge
> Priority: Major
>
> Many Spark SQL users in my company have asked for a way to control the number of output files in Spark SQL. The users prefer not to use function repartition\(n\) or coalesce(n, shuffle) that require them to write and deploy Scala/Java/Python code.
>
> There are use cases to either reduce or increase the number.
>
> The DataFrame API has repartition/coalesce for a long time. However, we do not have an equivalent functionality in SQL queries. We propose adding the following Hive-style Coalesce hint to Spark SQL.
> {noformat}
> /*+ COALESCE(n, shuffle) */
> /*+ REPARTITION(n) */
> {noformat}
> REPARTITION\(n\) is equal to COALESCE(n, shuffle=true).
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