beyond1920 commented on a change in pull request #8203:
[Flink-12208][table-planner-blink] Support translation from StreamExecSort /
TemporalSort / SortLimit/ Limit to StreamTransformation.
URL: https://github.com/apache/flink/pull/8203#discussion_r276629617
##########
File path:
flink-table/flink-table-planner-blink/src/main/scala/org/apache/flink/table/plan/nodes/physical/stream/StreamExecLimit.scala
##########
@@ -72,4 +89,78 @@ class StreamExecLimit(
.item("fetch", RelExplainUtil.fetchToString(fetch))
}
+ //~ ExecNode methods
-----------------------------------------------------------
+
+ override def getInputNodes: util.List[ExecNode[StreamTableEnvironment, _]] =
{
+ List(getInput.asInstanceOf[ExecNode[StreamTableEnvironment, _]])
+ }
+
+ override protected def translateToPlanInternal(
+ tableEnv: StreamTableEnvironment): StreamTransformation[BaseRow] = {
+ if (fetch == null) {
+ throw new TableException(
+ "FETCH is missed, which on streaming table is not supported currently")
+ }
+ val inputRowTypeInfo =
FlinkTypeFactory.toInternalRowType(getInput.getRowType).toTypeInfo
+ val generateRetraction = StreamExecRetractionRules.isAccRetract(this)
+ val tableConfig = tableEnv.getConfig
+ val minIdleStateRetentionTime = tableConfig.getMinIdleStateRetentionTime
+ val maxIdleStateRetentionTime = tableConfig.getMaxIdleStateRetentionTime
+
+ // rankStart begin with 1
+ val rankRange = new ConstantRankRange(limitStart + 1, limitEnd)
+ val rankType = RankType.ROW_NUMBER
+ val outputRankNumber = false
+ // TODO Use RankFunction underlying StreamExecLimit currently
Review comment:
Because SortLimit and Limit takes `limited` elements from `offset`, which is
very similar to TopN, and could use AppendRankFunction or UpdateRankFunction
under some as optimization in some scenarios. BTW, maybe RankFunction is not a
good name, it's only for TopN.
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