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https://issues.apache.org/jira/browse/SPARK-21707?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Hyukjin Kwon resolved SPARK-21707.
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Resolution: Incomplete
> Improvement a special case for non-deterministic filters in optimizer
> ---------------------------------------------------------------------
>
> Key: SPARK-21707
> URL: https://issues.apache.org/jira/browse/SPARK-21707
> Project: Spark
> Issue Type: Improvement
> Components: SQL
> Affects Versions: 2.3.0
> Reporter: caoxuewen
> Priority: Major
> Labels: bulk-closed
>
> 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 filters. Deal with that we only need to read user needs
> fields for non-deterministic filters in optimizer.
> For example, the condition of filters is nondeterministic. e.g:contains
> nondeterministic function(rand function), HiveTableScans optimizer generated:
> ```
> HiveTableScans plan:Aggregate [k#2L], [k#2L, k#2L, sum(cast(id#1 as bigint))
> AS sum(id)#395L]
> +- Project [d004#205 AS id#1, CEIL(c010#214) AS k#2L]
> +- Filter ((isnotnull(d004#205) && (rand(-4530215890880734772) <= 0.5)) &&
> NOT (cast(cast(d004#205 as decimal(10,0)) as decimal(11,1)) = 0.0))
> +- MetastoreRelation XXX_database, XXX_table
> HiveTableScans plan:Project [d004#205 AS id#1, CEIL(c010#214) AS k#2L]
> +- Filter ((isnotnull(d004#205) && (rand(-4530215890880734772) <= 0.5)) &&
> NOT (cast(cast(d004#205 as decimal(10,0)) as decimal(11,1)) = 0.0))
> +- MetastoreRelation XXX_database, XXX_table
> HiveTableScans plan:Filter ((isnotnull(d004#205) &&
> (rand(-4530215890880734772) <= 0.5)) && NOT (cast(cast(d004#205 as
> decimal(10,0)) as decimal(11,1)) = 0.0))
> +- MetastoreRelation XXX_database, XXX_table
> HiveTableScans plan:MetastoreRelation XXX_database, XXX_table
> ```
> so HiveTableScan will read all the fields from table. but we only need to
> ‘d004’ and 'c010' . it will affect the performance of task.
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