be/src/exec/cte-producer-node.h

// Licensed to the Apache Software Foundation (ASF) under one
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// 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 distributed under the License is distributed on an
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// KIND, either express or implied.  See the License for the
// specific language governing permissions and limitations
// under the License.

#pragma once

#include "exec/exec-node.h"
#include "runtime/local-exchanger.h"

namespace impala {

class LocalExchanger;

class CTEProducerPlanNode : public PlanNode {
 public:
  Status Init(const TPlanNode& tnode, FragmentState* state) override;
  Status CreateExecNode(RuntimeState* state, ExecNode** node) const override;
  ~CTEProducerPlanNode() override = default;

  string GetCTEName(int32_t index) const {
    return tnode_->cte_producer.name + "_" + std::to_string(index);
  }

  std::map<int32_t, std::unique_ptr<LocalExchanger>> exchangers_;

  /// True if any hash join or nested-loop join in the child plan-node subtree uses a
  /// separate build fragment and returns build-side tuples in its output rows. When true,
  /// each pushed RowBatch must be deep-copied so the exchanger holds no references to
  /// the build fragment's hash-table memory.
  bool needs_batch_deep_copy_ = false;
};

/// Node that buffers results produced by a Common Table Expression into a
/// LocalExchanger. It's expected to be the root of a fragment; on Open it
/// accumulates all results from its children; GetNext() waits for all consumers
/// (executing in other fragments) to consume the results, then returns eos.
class CTEProducerNode : public ExecNode {
 public:
  CTEProducerNode(
      ObjectPool* pool, const CTEProducerPlanNode& pnode, RuntimeState* state);

  Status Prepare(RuntimeState* state) override;
  Status Open(RuntimeState* state) override;
  Status GetNext(RuntimeState* state, RowBatch* row_batch, bool* eos) override;
  Status Reset(RuntimeState* state, RowBatch* row_batch) override;
  void Close(RuntimeState* state) override;
  void DebugString(int indentation_level, std::stringstream* out) const override;

 private:
  string name_;
  LocalExchanger* exchanger_;
  const bool needs_batch_deep_copy_;
};

}