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https://issues.apache.org/jira/browse/FLINK-3848?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15697953#comment-15697953
]
ASF GitHub Bot commented on FLINK-3848:
---------------------------------------
Github user wuchong commented on a diff in the pull request:
https://github.com/apache/flink/pull/2810#discussion_r89671128
--- Diff:
flink-libraries/flink-table/src/main/scala/org/apache/flink/api/table/sources/CsvTableSource.scala
---
@@ -102,11 +107,43 @@ class CsvTableSource(
* Do not use it in Table API programs.
*/
override def getDataStream(streamExecEnv: StreamExecutionEnvironment):
DataStream[Row] = {
- streamExecEnv.createInput(createCsvInput(), returnType)
+ streamExecEnv.createInput(createCsvInput(),
projectionReturnTypeWithOrder.getOrElse(returnType))
+ }
+
+ /** Returns a [[TableSource]] with ability to project fields */
+ override def setProjection(fields: Array[Int]): CsvTableSource = {
+ val mask = new Array[Boolean](fieldNames.length)
+ fields.foreach(mask(_) = true)
+ val orderedReturnType = fields.map(fieldTypes(_))
+ val indexDiff = fieldNames.length - fields.length
+ val order = fields.map(f => f -
indexDiff).zipWithIndex.sortBy(_._1).map(_._2)
+ val source = copy
--- End diff --
I would like use the `newFieldNames` and `newFieldTypes` to create a new
`CsvTableSource` instead of a same copy, so that we do not need
`orderedReturnType`. What do you think ?
> Add ProjectableTableSource interface and translation rule
> ---------------------------------------------------------
>
> Key: FLINK-3848
> URL: https://issues.apache.org/jira/browse/FLINK-3848
> Project: Flink
> Issue Type: New Feature
> Components: Table API & SQL
> Reporter: Fabian Hueske
> Assignee: Anton Solovev
>
> Add a {{ProjectableTableSource}} interface for {{TableSource}} implementation
> that support projection push-down.
> The interface could look as follows
> {code}
> def trait ProjectableTableSource {
> def setProjection(fields: Array[String]): Unit
> }
> {code}
> In addition we need Calcite rules to push a projection into a TableScan that
> refers to a {{ProjectableTableSource}}. We might need to tweak the cost model
> as well to push the optimizer in the right direction.
> Moreover, the {{CsvTableSource}} could be extended to implement
> {{ProjectableTableSource}}.
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