sdks/java/extensions/sql/src/main/java/org/apache/beam/sdk/extensions/sql/impl/rel/BeamIOSourceRel.java

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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 "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
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package org.apache.beam.sdk.extensions.sql.impl.rel;

import static org.apache.beam.vendor.calcite.v1_20_0.com.google.common.base.Preconditions.checkArgument;

import java.util.List;
import java.util.Map;
import org.apache.beam.sdk.extensions.sql.impl.BeamCalciteTable;
import org.apache.beam.sdk.extensions.sql.impl.BeamTableStatistics;
import org.apache.beam.sdk.extensions.sql.impl.planner.BeamCostModel;
import org.apache.beam.sdk.extensions.sql.impl.planner.NodeStats;
import org.apache.beam.sdk.extensions.sql.impl.utils.CalciteUtils;
import org.apache.beam.sdk.extensions.sql.meta.BeamSqlTable;
import org.apache.beam.sdk.extensions.sql.meta.BeamSqlTableFilter;
import org.apache.beam.sdk.extensions.sql.meta.DefaultTableFilter;
import org.apache.beam.sdk.schemas.Schema;
import org.apache.beam.sdk.transforms.PTransform;
import org.apache.beam.sdk.values.PBegin;
import org.apache.beam.sdk.values.PCollection;
import org.apache.beam.sdk.values.PCollectionList;
import org.apache.beam.sdk.values.Row;
import org.apache.beam.vendor.calcite.v1_20_0.org.apache.calcite.plan.RelOptCluster;
import org.apache.beam.vendor.calcite.v1_20_0.org.apache.calcite.plan.RelOptCost;
import org.apache.beam.vendor.calcite.v1_20_0.org.apache.calcite.plan.RelOptPlanner;
import org.apache.beam.vendor.calcite.v1_20_0.org.apache.calcite.plan.RelOptTable;
import org.apache.beam.vendor.calcite.v1_20_0.org.apache.calcite.plan.RelTraitSet;
import org.apache.beam.vendor.calcite.v1_20_0.org.apache.calcite.prepare.RelOptTableImpl;
import org.apache.beam.vendor.calcite.v1_20_0.org.apache.calcite.rel.RelWriter;
import org.apache.beam.vendor.calcite.v1_20_0.org.apache.calcite.rel.core.TableScan;
import org.apache.beam.vendor.calcite.v1_20_0.org.apache.calcite.rel.metadata.RelMetadataQuery;
import org.apache.beam.vendor.calcite.v1_20_0.org.apache.calcite.rel.type.RelDataType;

/** BeamRelNode to replace a {@code TableScan} node. */
public class BeamIOSourceRel extends TableScan implements BeamRelNode {
  public static final double CONSTANT_WINDOW_SIZE = 10d;
  private final BeamSqlTable beamTable;
  private final BeamCalciteTable calciteTable;
  private final Map<String, String> pipelineOptions;
  private final List<String> usedFields;
  private final BeamSqlTableFilter tableFilters;

  public BeamIOSourceRel(
      RelOptCluster cluster,
      RelTraitSet traitSet,
      RelOptTable table,
      BeamSqlTable beamTable,
      List<String> usedFields,
      BeamSqlTableFilter tableFilters,
      Map<String, String> pipelineOptions,
      BeamCalciteTable calciteTable) {
    super(cluster, traitSet, table);
    this.beamTable = beamTable;
    this.usedFields = usedFields;
    this.tableFilters = tableFilters;
    this.calciteTable = calciteTable;
    this.pipelineOptions = pipelineOptions;
  }

  public BeamIOSourceRel copy(
      RelDataType newType, List<String> usedFields, BeamSqlTableFilter tableFilters) {
    RelOptTable relOptTable =
        newType == null ? table : ((RelOptTableImpl) getTable()).copy(newType);
    tableFilters = tableFilters == null ? this.tableFilters : tableFilters;

    return new BeamIOSourceRel(
        getCluster(),
        traitSet,
        relOptTable,
        beamTable,
        usedFields,
        tableFilters,
        pipelineOptions,
        calciteTable);
  }

  @Override
  public double estimateRowCount(RelMetadataQuery mq) {
    BeamTableStatistics rowCountStatistics = calciteTable.getStatistic();
    if (beamTable.isBounded() == PCollection.IsBounded.BOUNDED) {
      return rowCountStatistics.getRowCount();
    } else {
      return rowCountStatistics.getRate();
    }
  }

  @Override
  public NodeStats estimateNodeStats(RelMetadataQuery mq) {
    BeamTableStatistics rowCountStatistics = calciteTable.getStatistic();
    double window =
        (beamTable.isBounded() == PCollection.IsBounded.BOUNDED)
            ? rowCountStatistics.getRowCount()
            : CONSTANT_WINDOW_SIZE;
    return NodeStats.create(rowCountStatistics.getRowCount(), rowCountStatistics.getRate(), window);
  }

  @Override
  public PCollection.IsBounded isBounded() {
    return beamTable.isBounded();
  }

  @Override
  public PTransform<PCollectionList<Row>, PCollection<Row>> buildPTransform() {
    return new Transform();
  }

  @Override
  public RelWriter explainTerms(RelWriter pw) {
    super.explainTerms(pw);

    // This is done to tell Calcite planner that BeamIOSourceRel cannot be simply substituted by
    //  another BeamIOSourceRel, except for when they carry the same content.
    if (!usedFields.isEmpty()) {
      pw.item("usedFields", usedFields.toString());
    }
    if (!(tableFilters instanceof DefaultTableFilter)) {
      pw.item(tableFilters.getClass().getSimpleName(), tableFilters.toString());
    }

    return pw;
  }

  private class Transform extends PTransform<PCollectionList<Row>, PCollection<Row>> {

    @Override
    public PCollection<Row> expand(PCollectionList<Row> input) {
      checkArgument(
          input.size() == 0,
          "Should not have received input for %s: %s",
          BeamIOSourceRel.class.getSimpleName(),
          input);

      final PBegin begin = input.getPipeline().begin();

      if (usedFields.isEmpty() && tableFilters instanceof DefaultTableFilter) {
        return beamTable.buildIOReader(begin);
      }

      final Schema newBeamSchema = CalciteUtils.toSchema(getRowType());
      return beamTable.buildIOReader(begin, tableFilters, usedFields).setRowSchema(newBeamSchema);
    }
  }

  @Override
  public RelOptCost computeSelfCost(RelOptPlanner planner, RelMetadataQuery mq) {
    // We should technically avoid this function. This happens if we are in JDBC path or the
    // costFactory is not set correctly.
    double rowCount = this.estimateRowCount(mq);
    return planner.getCostFactory().makeCost(rowCount, rowCount, rowCount);
  }

  @Override
  public BeamCostModel beamComputeSelfCost(RelOptPlanner planner, RelMetadataQuery mq) {
    NodeStats estimates = BeamSqlRelUtils.getNodeStats(this, mq);
    return BeamCostModel.FACTORY
        .makeCost(estimates.getRowCount(), estimates.getRate())
        .multiplyBy(getRowType().getFieldCount());
  }

  public BeamSqlTable getBeamSqlTable() {
    return beamTable;
  }

  @Override
  public Map<String, String> getPipelineOptions() {
    return pipelineOptions;
  }
}