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Posted to issues@spark.apache.org by "Hyukjin Kwon (JIRA)" <ji...@apache.org> on 2019/05/21 04:15:39 UTC
[jira] [Resolved] (SPARK-22639) no rowcount estimation returned if
groupby clause involves substring
[ https://issues.apache.org/jira/browse/SPARK-22639?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Hyukjin Kwon resolved SPARK-22639.
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Resolution: Incomplete
> no rowcount estimation returned if groupby clause involves substring
> --------------------------------------------------------------------
>
> Key: SPARK-22639
> URL: https://issues.apache.org/jira/browse/SPARK-22639
> Project: Spark
> Issue Type: Bug
> Components: Optimizer, SQL
> Affects Versions: 2.2.0
> Reporter: ey-chih chow
> Priority: Major
> Labels: bulk-closed
> Original Estimate: 504h
> Remaining Estimate: 504h
>
> CBO can not estimate rowcount if the groupby clause of a query involves the expression substring. For example, we can not estimate the row count of the following query, extracted from TPC-DS queries and based on the TPC-DS schema:
> SELECT item.`i_brand`, count(1), date_dim.`d_year`, item.`i_brand_id`, sum(store_sales.`ss_ext_sales_price`) AS `ext_price`, item.`i_item_sk`
> FROM store_sales INNER JOIN date_dim ON (date_dim.`d_date_sk` = store_sales.`ss_sold_date_sk`) INNER JOIN item ON (store_sales.`ss_item_sk` = item.`i_item_sk`)
> GROUP BY item.`i_brand`, date_dim.`d_date`, substring(item.`i_item_desc`, 1, 30), date_dim.`d_year`, item.`i_brand_id`, item.`i_item_sk`
>
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