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Posted to issues@spark.apache.org by "Huaxin Gao (JIRA)" <ji...@apache.org> on 2017/07/05 21:52:00 UTC
[jira] [Commented] (SPARK-15491) JSON serialization fails for JDBC
DataFrames
[ https://issues.apache.org/jira/browse/SPARK-15491?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16075491#comment-16075491 ]
Huaxin Gao commented on SPARK-15491:
------------------------------------
Hi Marc,
Is there a use case you need to convert JDBCRelation to JSON?
Spark added a method shouldConvertToJson to limit certain node types to convert to JSON after #14990, and JDBCRelation is not allowed to convert, so this Jira won't be fixed unless there is a requirement.
> JSON serialization fails for JDBC DataFrames
> --------------------------------------------
>
> Key: SPARK-15491
> URL: https://issues.apache.org/jira/browse/SPARK-15491
> Project: Spark
> Issue Type: Bug
> Components: SQL
> Affects Versions: 2.0.0
> Environment: MacOS 10.11.5, Spark 2.0.0-preview
> Reporter: Marc Prud'hommeaux
>
> The TreeNode.toJSON feature implemented in SPARK-12321 fails with an assertion error on DataFrames that use JDBC in spark 2.0.0-preview:
> {code}
> scala> sqlContext.read.json("examples/src/main/resources/people.json").select("name", "age").agg(avg("age"), count("name")).filter(avg("age") > 10).queryExecution.logical.toJSON
> res113: String = [{"class":"org.apache.spark.sql.catalyst.plans.logical.Filter","num-children":1,"condition":[{"class":"org.apache.spark.sql.catalyst.expressions.GreaterThan","num-children":2,"left":0,"right":1},{"class":"org.apache.spark.sql.catalyst.expressions.aggregate.AggregateExpression","num-children":1,...
> scala> sqlContext.read.format("jdbc").options(db + ("dbtable" -> "categories")).load().queryExecution.logical.simpleString
> res120: String = Relation[category#2148,categoryname#2149] JDBCRelation(categories)
> scala> sqlContext.read.format("jdbc").options(db + ("dbtable" -> "categories")).load().queryExecution.logical.toJSON
> java.lang.AssertionError: assertion failed
> at scala.Predef$.assert(Predef.scala:156)
> at org.apache.spark.sql.catalyst.trees.TreeNode.org$apache$spark$sql$catalyst$trees$TreeNode$$parseToJson(TreeNode.scala:598)
> at org.apache.spark.sql.catalyst.trees.TreeNode$$anonfun$jsonFields$2.apply(TreeNode.scala:562)
> at org.apache.spark.sql.catalyst.trees.TreeNode$$anonfun$jsonFields$2.apply(TreeNode.scala:553)
> at scala.collection.TraversableLike$$anonfun$map$1.apply(TraversableLike.scala:234)
> at scala.collection.TraversableLike$$anonfun$map$1.apply(TraversableLike.scala:234)
> at scala.collection.immutable.List.foreach(List.scala:381)
> at scala.collection.TraversableLike$class.map(TraversableLike.scala:234)
> at scala.collection.immutable.List.map(List.scala:285)
> at org.apache.spark.sql.catalyst.trees.TreeNode.jsonFields(TreeNode.scala:553)
> at org.apache.spark.sql.catalyst.trees.TreeNode.org$apache$spark$sql$catalyst$trees$TreeNode$$collectJsonValue$1(TreeNode.scala:538)
> at org.apache.spark.sql.catalyst.trees.TreeNode.jsonValue(TreeNode.scala:543)
> at org.apache.spark.sql.catalyst.trees.TreeNode.toJSON(TreeNode.scala:529)
> ... 48 elided
> {code}
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