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https://issues.apache.org/jira/browse/FLINK-3940?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15404141#comment-15404141
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ASF GitHub Bot commented on FLINK-3940:
---------------------------------------
Github user twalthr commented on a diff in the pull request:
https://github.com/apache/flink/pull/2282#discussion_r73172521
--- Diff:
flink-libraries/flink-table/src/main/scala/org/apache/flink/api/table/plan/logical/operators.scala
---
@@ -150,6 +150,47 @@ case class Sort(order: Seq[Ordering], child:
LogicalNode) extends UnaryNode {
}
}
+case class Offset(offset: Int, child: LogicalNode) extends UnaryNode {
+ override def output: Seq[Attribute] = child.output
+
+ override protected[logical] def construct(relBuilder: RelBuilder):
RelBuilder = {
+ child.construct(relBuilder)
+ relBuilder.limit(offset, -1)
+ }
+
+ override def validate(tableEnv: TableEnvironment): LogicalNode = {
+ if (tableEnv.isInstanceOf[StreamTableEnvironment]) {
+ throw new TableException(s"Offset on stream tables is currently not
supported.")
+ }
+ if (!child.validate(tableEnv).isInstanceOf[Sort]) {
+ throw new TableException(s"Offset operator must follow behind
orderBy clause.")
+ }
+ super.validate(tableEnv)
+ }
+}
+
+case class Fetch(fetch: Int, child: LogicalNode) extends UnaryNode {
+ override def output: Seq[Attribute] = child.output
+
+ override protected[logical] def construct(relBuilder: RelBuilder):
RelBuilder = {
+
+ val newChild = child.asInstanceOf[Offset].child
+ newChild.construct(relBuilder)
+ val relNode = child.toRelNode(relBuilder).asInstanceOf[LogicalSort]
+ relBuilder.limit(RexLiteral.intValue(relNode.offset), fetch)
+ }
+
+ override def validate(tableEnv: TableEnvironment): LogicalNode = {
+ if (tableEnv.isInstanceOf[StreamTableEnvironment]) {
+ throw new TableException(s"Fetch on stream tables is currently not
supported.")
+ }
+ if (!child.validate(tableEnv).isInstanceOf[Offset]) {
--- End diff --
Some comment as above.
> Add support for ORDER BY OFFSET FETCH
> -------------------------------------
>
> Key: FLINK-3940
> URL: https://issues.apache.org/jira/browse/FLINK-3940
> Project: Flink
> Issue Type: New Feature
> Components: Table API & SQL
> Affects Versions: 1.1.0
> Reporter: Fabian Hueske
> Assignee: GaoLun
> Priority: Minor
>
> Currently only ORDER BY without OFFSET and FETCH are supported.
> This issue tracks the effort to add support for OFFSET and FETCH and involves:
> - Implementing the execution strategy in `DataSetSort`
> - adapting the `DataSetSortRule` to support OFFSET and FETCH
> - extending the Table API and validation to support OFFSET and FETCH and
> generate a corresponding RelNode.
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