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https://issues.apache.org/jira/browse/SPARK-6444?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14374831#comment-14374831
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Cheng Lian commented on SPARK-6444:
-----------------------------------
This issue also exposes another issue in the analyzer, which is tracked in
SPARK-6452.
> Sum expression should remain unresolved if the data type isn't a numeric type
> -----------------------------------------------------------------------------
>
> Key: SPARK-6444
> URL: https://issues.apache.org/jira/browse/SPARK-6444
> Project: Spark
> Issue Type: Bug
> Components: SQL
> Affects Versions: 1.0.2, 1.1.1, 1.2.1, 1.3.0
> Reporter: Cheng Lian
> Assignee: Cheng Lian
>
> Spark shell session for reproducing this issue:
> {code}
> import sqlContext._
> sql("""
> CREATE TABLE IF NOT EXISTS ut (
> c1 STRING,
> c2 STRING
> )
> """)
> sql("""
> SELECT SUM(c3) FROM (
> SELECT SUM(c1) AS c3, 0 AS c4 FROM ut -- (1)
> UNION ALL
> SELECT 0 AS c3, COUNT(c2) AS c4 FROM ut -- (2)
> ) t
> """).queryExecution.optimizedPlan
> {code}
> Exception thrown:
> {noformat}
> java.util.NoSuchElementException: key not found: c3#10
> at scala.collection.MapLike$class.default(MapLike.scala:228)
> at
> org.apache.spark.sql.catalyst.expressions.AttributeMap.default(AttributeMap.scala:29)
> at scala.collection.MapLike$class.apply(MapLike.scala:141)
> at
> org.apache.spark.sql.catalyst.expressions.AttributeMap.apply(AttributeMap.scala:29)
> at
> org.apache.spark.sql.catalyst.optimizer.UnionPushdown$$anonfun$1.applyOrElse(Optimizer.scala:80)
> at
> org.apache.spark.sql.catalyst.optimizer.UnionPushdown$$anonfun$1.applyOrElse(Optimizer.scala:79)
> at
> org.apache.spark.sql.catalyst.trees.TreeNode$$anonfun$3.apply(TreeNode.scala:187)
> at
> org.apache.spark.sql.catalyst.trees.TreeNode$$anonfun$3.apply(TreeNode.scala:187)
> at
> org.apache.spark.sql.catalyst.trees.CurrentOrigin$.withOrigin(TreeNode.scala:50)
> at
> org.apache.spark.sql.catalyst.trees.TreeNode.transformDown(TreeNode.scala:186)
> at
> org.apache.spark.sql.catalyst.trees.TreeNode.transform(TreeNode.scala:177)
> at
> org.apache.spark.sql.catalyst.optimizer.UnionPushdown$.pushToRight(Optimizer.scala:79)
> at
> org.apache.spark.sql.catalyst.optimizer.UnionPushdown$$anonfun$apply$1$$anonfun$applyOrElse$6.apply(Optimizer.scala:101)
> at
> org.apache.spark.sql.catalyst.optimizer.UnionPushdown$$anonfun$apply$1$$anonfun$applyOrElse$6.apply(Optimizer.scala:101)
> ...
> {noformat}
> The analyzed plan of the query is:
> {noformat}
> == Analyzed Logical Plan ==
> !Aggregate [], [SUM(CAST(c3#153, DoubleType)) AS _c0#157]
> (c)
> Union
> Project [CAST(c3#153, StringType) AS c3#164,c4#163L]
> (d)
> Project [c3#153,CAST(c4#154, LongType) AS c4#163L]
> Aggregate [], [SUM(CAST(c1#158, DoubleType)) AS c3#153,0 AS c4#154]
> (b)
> MetastoreRelation default, ut, None
> Project [CAST(c3#155, StringType) AS c3#162,c4#156L]
> (a)
> Aggregate [], [0 AS c3#155,COUNT(c2#161) AS c4#156L]
> MetastoreRelation default, ut, None
> {noformat}
> This case is very interesting. It involves 2 analysis rules, {{WidenTypes}}
> and {{PropagateStrings}}, and 1 optimizer rule, {{UnionPushdown}}. To see the
> details, we can turn on TRACE level log and check detailed rule execution
> process. The TL;DR is:
> # Since {{c1}} is STRING, {{SUM(c1)}} is also STRING (which is the root cause
> of the whole issue).
> # {{c3}} in {{(1)}} is STRING, while the one in {{(2)}} is INT. Thus
> {{WidenTypes}} casts the latter to STRING to ensure both sides of the UNION
> have the same schema. See {{(a)}}.
> # {{PropagateStrings}} casts {{c1}} in {{SUM(c1)}} to DOUBLE, which
> consequently changes data type of {{SUM(c1)}} and {{c3}} to DOUBLE. See
> {{(b)}}.
> # {{c3}} in the top level {{Aggregate}} is resolved as DOUBLE (c)
> # Since schemas of the two sides of the UNION are different again,
> {{WidenTypes}} casts {{SUM(c1) AS c3}} to STRING. See {{(d)}}.
> # The top level {{Aggregate}} becomes unresolved since {{c3#153}} is hidden
> by {{(d)}} now.
> # In the optimizing phase, {{UnionPushdown}} throws because the top level
> {{Aggregate}} is unresolved.
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