Github user wuchong commented on a diff in the pull request:
https://github.com/apache/flink/pull/2282#discussion_r71898802
--- Diff:
flink-libraries/flink-table/src/main/scala/org/apache/flink/api/table/plan/logical/operators.scala
---
@@ -150,6 +150,41 @@ 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.")
+ }
+ 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.")
+ }
--- End diff --
I think we need to check the 'fetch' is followed after a 'orderby' and
'offset' here. Otherwise, the class cast in construct will throw exception.
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