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https://issues.apache.org/jira/browse/SPARK-33915?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17257647#comment-17257647
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Ted Yu commented on SPARK-33915:
--------------------------------
Here is sample code for capturing the column and fields in downstream
PredicatePushDown.scala
{code}
private val JSONCapture = "`GetJsonObject\\((.*),(.*)\\)`".r
private def transformGetJsonObject(p: Predicate): Predicate = {
val eq = p.asInstanceOf[sources.EqualTo]
eq.attribute match {
case JSONCapture(column,field) =>
val colName = column.toString.split("#")(0)
val names = field.toString.split("\\.").foldLeft(List[String]()){(z, n)
=> z :+ "->'"+n+"'" }
sources.EqualTo(colName + names.slice(1, names.size).mkString(""),
eq.value).asInstanceOf[Predicate]
case _ => sources.EqualTo("foo", "bar").asInstanceOf[Predicate]
}
}
{code}
> Allow json expression to be pushable column
> -------------------------------------------
>
> Key: SPARK-33915
> URL: https://issues.apache.org/jira/browse/SPARK-33915
> Project: Spark
> Issue Type: Improvement
> Components: Spark Core
> Affects Versions: 3.0.1
> Reporter: Ted Yu
> Assignee: Apache Spark
> Priority: Major
>
> Currently PushableColumnBase provides no support for json / jsonb expression.
> Example of json expression:
> {code}
> get_json_object(phone, '$.code') = '1200'
> {code}
> If non-string literal is part of the expression, the presence of cast() would
> complicate the situation.
> Implication is that implementation of SupportsPushDownFilters doesn't have a
> chance to perform pushdown even if third party DB engine supports json
> expression pushdown.
> This issue is for discussion and implementation of Spark core changes which
> would allow json expression to be recognized as pushable column.
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