content: /*
   * 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
   * 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.
   */
  package org.apache.calcite.plan;
  
  import org.apache.calcite.config.CalciteConnectionConfig;
  import org.apache.calcite.jdbc.CalciteSchema;
  import org.apache.calcite.materialize.Lattice;
  import org.apache.calcite.materialize.MaterializationService;
  import org.apache.calcite.materialize.TileKey;
  import org.apache.calcite.rel.RelNode;
  import org.apache.calcite.util.ImmutableBitSet;
  import org.apache.calcite.util.Pair;
  
  import org.checkerframework.checker.nullness.qual.Nullable;
  
  import java.util.List;
  
  /**
   * Use of a lattice by the query optimizer.
   */
  public class RelOptLattice {
    public final Lattice lattice;
    public final RelOptTable starRelOptTable;
  
    public RelOptLattice(Lattice lattice, RelOptTable starRelOptTable) {
      this.lattice = lattice;
      this.starRelOptTable = starRelOptTable;
    }
  
    public RelOptTable rootTable() {
      return lattice.rootNode.relOptTable();
    }
  
    /** Rewrites a relational expression to use a lattice.
     *
     * <p>Returns null if a rewrite is not possible.
     *
     * @param node Relational expression
     * @return Rewritten query
     */
    public @Nullable RelNode rewrite(RelNode node) {
      return RelOptMaterialization.tryUseStar(node, starRelOptTable);
    }
  
    /** Retrieves a materialized table that will satisfy an aggregate query on
     * the star table.
     *
     * <p>The current implementation creates a materialization and populates it,
     * provided that {@link Lattice#auto} is true.
     *
     * <p>Future implementations might return materializations at a different
     * level of aggregation, from which the desired result can be obtained by
     * rolling up.
     *
     * @param planner Current planner
     * @param groupSet Grouping key
     * @param measureList Calls to aggregate functions
     * @return Materialized table
     */
    public @Nullable Pair<CalciteSchema.TableEntry, TileKey> getAggregate(
        RelOptPlanner planner, ImmutableBitSet groupSet,
        List<Lattice.Measure> measureList) {
      final CalciteConnectionConfig config =
          planner.getContext().unwrap(CalciteConnectionConfig.class);
      if (config == null) {
        return null;
      }
      final MaterializationService service = MaterializationService.instance();
      boolean create = lattice.auto && config.createMaterializations();
      final CalciteSchema schema = starRelOptTable.unwrap(CalciteSchema.class);
      if (schema == null) {
        throw new IllegalArgumentException("Can't get CalciteSchema from "
            + starRelOptTable);
      }
      return service.defineTile(lattice, groupSet, measureList, schema, create,
          false);
    }
  }
  