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https://issues.apache.org/jira/browse/SPARK-21520?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16144024#comment-16144024
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Apache Spark commented on SPARK-21520:
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User 'heary-cao' has created a pull request for this issue:
https://github.com/apache/spark/pull/18969
> Improvement a special case for non-deterministic projects in optimizer
> ----------------------------------------------------------------------
>
> Key: SPARK-21520
> URL: https://issues.apache.org/jira/browse/SPARK-21520
> Project: Spark
> Issue Type: Improvement
> Components: SQL
> Affects Versions: 2.3.0
> Reporter: caoxuewen
>
> Currently, Did a lot of special handling for non-deterministic projects and
> filters in optimizer. but not good enough. this patch add a new special case
> for non-deterministic projects. Deal with that we only need to read user
> needs fields for non-deterministic projects in optimizer.
> For example, the fields of project contains nondeterministic function(rand
> function), after a executedPlan optimizer generated:
> *HashAggregate(keys=[k#403L], functions=[partial_sum(cast(id#402 as
> bigint))], output=[k#403L, sum#800L])
> +- Project [d004#607 AS id#402, FLOOR((rand(8828525941469309371) * 10000.0))
> AS k#403L]
> +- HiveTableScan [c030#606L, d004#607, d005#608, d025#609, c002#610,
> d023#611, d024#612, c005#613L, c008#614, c009#615, c010#616, d021#617,
> d022#618, c017#619, c018#620, c019#621, c020#622, c021#623, c022#624,
> c023#625, c024#626, c025#627, c026#628, c027#629, ... 169 more fields],
> MetastoreRelation XXX_database, XXX_table
> HiveTableScan will read all the fields from table. but we only need to ‘d004’
> . it will affect the performance of task.
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