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From "Apache Spark (JIRA)" <j...@apache.org>
Subject [jira] [Assigned] (SPARK-9066) Improve cartesian performance
Date Wed, 15 Jul 2015 09:21:04 GMT

     [ https://issues.apache.org/jira/browse/SPARK-9066?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Apache Spark reassigned SPARK-9066:
-----------------------------------

    Assignee: Apache Spark

> Improve cartesian performance 
> ------------------------------
>
>                 Key: SPARK-9066
>                 URL: https://issues.apache.org/jira/browse/SPARK-9066
>             Project: Spark
>          Issue Type: Improvement
>          Components: SQL
>            Reporter: Weizhong
>            Assignee: Apache Spark
>            Priority: Minor
>
> Currently, for CartesianProduct, if right plan partition number are small than left partition
number, then then performance is bad as need do many times scan for right plan.
> For example:
> {noformat}
> with single_value as (
>   select max(1) tpcds_val from date_dim
> )
> select sum(ss_quantity * ss_sales_price) ssales, tpcds_val
> from store_sales, single_value
> group by tpcds_val
> {noformat}
> above SQL clause, right plan only have 1 partition, left plan have 1823 partiton(in our
test), then for each left plan partition we need scan data from hdfs for right plan.
> That is, for left plan we need scan _left_plan_partition_num_ times, for right plan we
need scan _left_plan_partition_num * right_plan_partition_num_ times, total is  _left_plan_partition_num
* left_plan_partition_num * right_plan_partition_num_ times



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