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Posted to issues@spark.apache.org by "Chen Zou (Jira)" <ji...@apache.org> on 2021/03/15 15:23:00 UTC
[jira] [Comment Edited] (SPARK-34694) Improve Spark SQL Source
Filter to allow pushdown of filters span multiple columns
[ https://issues.apache.org/jira/browse/SPARK-34694?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17301701#comment-17301701 ]
Chen Zou edited comment on SPARK-34694 at 3/15/21, 3:22 PM:
------------------------------------------------------------
Hi Hyukjin,
I think the design you described would work.
But the current org.apache.spark.sql.sources.Filter isn't built under the assumption that the 'value' parameter could be a column reference.
e.g. the findReferences member function does not consider value being a column references.
{quote} protected def findReferences(value: Any): Array[String] = value match {
case f: Filter => f.references
case _ => Array.empty
}
{quote}
And this is probably why org.apache.spark.sql.execution.datasources.v2.PushDownUtils would not push the cross-column filters down to data sources.
The end result is that cross-column filters don't get pushed down, from stderr of a spark job doing TPC-H Q12:
21/03/10 16:56:16.266 INFO V2ScanRelationPushDown:
Pushing operators to lineitem@[file:///home/colouser51/udpstorage/tpch/tbl_s1e1/lineitem]
Pushed Filters: Or(EqualTo(l_shipmode,MAIL),EqualTo(l_shipmode,SHIP)), GreaterThanOrEqual(l_receiptdate,1994-01-01), LessThan(l_receiptdate,1995-01-01)
Post-Scan Filters: (l_commitdate#11 < l_receiptdate#12),(l_shipdate#10 < l_commitdate#11)
Output: l_orderkey#0, l_shipdate#10, l_commitdate#11, l_receiptdate#12, l_shipmode#14
Regards,
Chen
was (Author: zinechant):
Hi Hyukjin,
I think the design you described would work.
But the current org.apache.spark.sql.sources.Filter isn't built under the assumption that the 'value' parameter could be a column reference.
e.g. the findReferences member function does not consider value being a column references.
{quote} protected def findReferences(value: Any): Array[String] = value match {
case f: Filter => f.references
case _ => Array.empty
}{quote}
And this is probably why org.apache.spark.sql.execution.datasources.v2.PushDownUtils would not push the cross-column filters down to data sources.
The end result is that cross-column filters don't get pushed down, from stderr of a spark job doing TPC-H Q12:
21/03/10 16:56:16.266 INFO V2ScanRelationPushDown:
Pushing operators to lineitem@file:///home/colouser51/udpstorage/tpch/tbl_s1e1/lineitem
Pushed Filters: Or(EqualTo(l_shipmode,MAIL),EqualTo(l_shipmode,SHIP)), GreaterThanOrEqual(l_receiptdate,1994-01-01), LessThan(l_receiptdate,1995-01-01)
Post-Scan Filters: (l_commitdate#11 < l_receiptdate#12),(l_shipdate#10 < l_commitdate#11)
Output: l_orderkey#0, l_shipdate#10, l_commitdate#11, l_receiptdate#12, l_shipmode#14
Regards,
Chen
> Improve Spark SQL Source Filter to allow pushdown of filters span multiple columns
> ----------------------------------------------------------------------------------
>
> Key: SPARK-34694
> URL: https://issues.apache.org/jira/browse/SPARK-34694
> Project: Spark
> Issue Type: Improvement
> Components: Spark Core
> Affects Versions: 3.0.0, 3.0.1, 3.0.2, 3.1.0, 3.1.1
> Reporter: Chen Zou
> Priority: Minor
>
> The current org.apache.spark.sql.sources.Filter abstract class only allows pushdown of filters on single column or sum of products of multiple such single-column filters.
> Filters on multiple columns cannot be pushed down through this Filter subclass to source, e.g. from TPC-H benchmark on lineitem table:
> (l_commitdate#11 < l_receiptdate#12)
> (l_shipdate#10 < l_commitdate#11)
>
> The current design probably originates from the point that columnar source has a hard time supporting these cross-column filters. But with batching implemented in columnar sources, they can still support cross-column filters. This issue tries to open up discussion on a more general Filter interface to allow pushing down cross-column filters.
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