org.apache.flink.table.planner.plan.rules.physical.stream.StreamExecLimitRule.scala Maven / Gradle / Ivy

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
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 * See the License for the specific language governing permissions and
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package org.apache.flink.table.planner.plan.rules.physical.stream

import org.apache.flink.table.planner.plan.`trait`.FlinkRelDistribution
import org.apache.flink.table.planner.plan.nodes.FlinkConventions
import org.apache.flink.table.planner.plan.nodes.logical.FlinkLogicalSort
import org.apache.flink.table.planner.plan.nodes.physical.stream.StreamExecLimit

import org.apache.calcite.plan.{RelOptRule, RelOptRuleCall}
import org.apache.calcite.rel.RelNode
import org.apache.calcite.rel.convert.ConverterRule

/**
  * Rule that matches [[FlinkLogicalSort]] with empty sort fields,
  * and converts it to [[StreamExecLimit]].
  */
class StreamExecLimitRule
  extends ConverterRule(
    classOf[FlinkLogicalSort],
    FlinkConventions.LOGICAL,
    FlinkConventions.STREAM_PHYSICAL,
    "StreamExecLimitRule") {

  override def matches(call: RelOptRuleCall): Boolean = {
    val sort: FlinkLogicalSort = call.rel(0)
    // only matches Sort with empty sort fields
    sort.getCollation.getFieldCollations.isEmpty
}

  override def convert(rel: RelNode): RelNode = {
    val sort = rel.asInstanceOf[FlinkLogicalSort]
    val input = sort.getInput

    // require SINGLETON exchange
    val newTraitSet = input.getTraitSet
      .replace(FlinkConventions.STREAM_PHYSICAL)
      .replace(FlinkRelDistribution.SINGLETON)
    val newInput = RelOptRule.convert(input, newTraitSet)

    // create StreamExecLimit
    val providedGlobalTraitSet = newTraitSet
    new StreamExecLimit(
      rel.getCluster,
      providedGlobalTraitSet,
      newInput,
      sort.offset,
      sort.fetch)
  }
}

object StreamExecLimitRule {
  val INSTANCE: RelOptRule = new StreamExecLimitRule
}