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https://issues.apache.org/jira/browse/SPARK-6213?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14351479#comment-14351479
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Littlestar commented on SPARK-6213:
-----------------------------------
above similar scala code is very hard to translate to java.
> sql.catalyst.expressions.Expression is not friendly to java
> -----------------------------------------------------------
>
> Key: SPARK-6213
> URL: https://issues.apache.org/jira/browse/SPARK-6213
> Project: Spark
> Issue Type: Improvement
> Components: SQL
> Affects Versions: 1.3.0
> Reporter: Littlestar
> Priority: Minor
>
> sql.sources.CatalystScan#
> public RDD<Row> buildScan(Seq<Attribute> requiredColumns, Seq<Expression>
> filters)
> I use java to extends BaseRelation, but sql.catalyst.expressions.Expression
> is not friendly to java, it's can't iterated by java, such as NodeName,
> NodeType.....
> DataSourceStrategy.scala#selectFilters
> {noformat}
> /**
> * Selects Catalyst predicate [[Expression]]s which are convertible into
> data source [[Filter]]s,
> * and convert them.
> */
> protected[sql] def selectFilters(filters: Seq[Expression]) = {
> def translate(predicate: Expression): Option[Filter] = predicate match {
> case expressions.EqualTo(a: Attribute, Literal(v, _)) =>
> Some(sources.EqualTo(a.name, v))
> case expressions.EqualTo(Literal(v, _), a: Attribute) =>
> Some(sources.EqualTo(a.name, v))
> case expressions.GreaterThan(a: Attribute, Literal(v, _)) =>
> Some(sources.GreaterThan(a.name, v))
> case expressions.GreaterThan(Literal(v, _), a: Attribute) =>
> Some(sources.LessThan(a.name, v))
> case expressions.LessThan(a: Attribute, Literal(v, _)) =>
> Some(sources.LessThan(a.name, v))
> case expressions.LessThan(Literal(v, _), a: Attribute) =>
> Some(sources.GreaterThan(a.name, v))
> case expressions.GreaterThanOrEqual(a: Attribute, Literal(v, _)) =>
> Some(sources.GreaterThanOrEqual(a.name, v))
> case expressions.GreaterThanOrEqual(Literal(v, _), a: Attribute) =>
> Some(sources.LessThanOrEqual(a.name, v))
> case expressions.LessThanOrEqual(a: Attribute, Literal(v, _)) =>
> Some(sources.LessThanOrEqual(a.name, v))
> case expressions.LessThanOrEqual(Literal(v, _), a: Attribute) =>
> Some(sources.GreaterThanOrEqual(a.name, v))
> case expressions.InSet(a: Attribute, set) =>
> Some(sources.In(a.name, set.toArray))
> case expressions.IsNull(a: Attribute) =>
> Some(sources.IsNull(a.name))
> case expressions.IsNotNull(a: Attribute) =>
> Some(sources.IsNotNull(a.name))
> case expressions.And(left, right) =>
> (translate(left) ++ translate(right)).reduceOption(sources.And)
> case expressions.Or(left, right) =>
> for {
> leftFilter <- translate(left)
> rightFilter <- translate(right)
> } yield sources.Or(leftFilter, rightFilter)
> case expressions.Not(child) =>
> translate(child).map(sources.Not)
> case _ => None
> }
> filters.flatMap(translate)
> }
> {noformat}
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