org.apache.druid.sql.calcite.aggregation.builtin.AvgSqlAggregator.java Source code

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Here is the source code for org.apache.druid.sql.calcite.aggregation.builtin.AvgSqlAggregator.java

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/*
 * 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.druid.sql.calcite.aggregation.builtin;

import com.google.common.collect.ImmutableList;
import com.google.common.collect.Iterables;
import org.apache.calcite.rel.core.AggregateCall;
import org.apache.calcite.rel.core.Project;
import org.apache.calcite.rex.RexBuilder;
import org.apache.calcite.sql.SqlAggFunction;
import org.apache.calcite.sql.fun.SqlStdOperatorTable;
import org.apache.calcite.sql.type.SqlTypeName;
import org.apache.druid.math.expr.ExprMacroTable;
import org.apache.druid.query.aggregation.AggregatorFactory;
import org.apache.druid.query.aggregation.CountAggregatorFactory;
import org.apache.druid.query.aggregation.post.ArithmeticPostAggregator;
import org.apache.druid.query.aggregation.post.FieldAccessPostAggregator;
import org.apache.druid.segment.column.ValueType;
import org.apache.druid.sql.calcite.aggregation.Aggregation;
import org.apache.druid.sql.calcite.aggregation.Aggregations;
import org.apache.druid.sql.calcite.aggregation.SqlAggregator;
import org.apache.druid.sql.calcite.expression.DruidExpression;
import org.apache.druid.sql.calcite.planner.Calcites;
import org.apache.druid.sql.calcite.planner.PlannerContext;
import org.apache.druid.sql.calcite.table.RowSignature;

import javax.annotation.Nullable;
import java.util.List;

public class AvgSqlAggregator implements SqlAggregator {
    @Override
    public SqlAggFunction calciteFunction() {
        return SqlStdOperatorTable.AVG;
    }

    @Nullable
    @Override
    public Aggregation toDruidAggregation(final PlannerContext plannerContext, final RowSignature rowSignature,
            final RexBuilder rexBuilder, final String name, final AggregateCall aggregateCall,
            final Project project, final List<Aggregation> existingAggregations,
            final boolean finalizeAggregations) {
        if (aggregateCall.isDistinct()) {
            return null;
        }

        final List<DruidExpression> arguments = Aggregations.getArgumentsForSimpleAggregator(plannerContext,
                rowSignature, aggregateCall, project);

        if (arguments == null) {
            return null;
        }

        final DruidExpression arg = Iterables.getOnlyElement(arguments);
        final ValueType sumType;

        // Use 64-bit sum regardless of the type of the AVG aggregator.
        if (SqlTypeName.INT_TYPES.contains(aggregateCall.getType().getSqlTypeName())) {
            sumType = ValueType.LONG;
        } else {
            sumType = ValueType.DOUBLE;
        }

        final ExprMacroTable macroTable = plannerContext.getExprMacroTable();

        final String fieldName;
        final String expression;

        if (arg.isDirectColumnAccess()) {
            fieldName = arg.getDirectColumn();
            expression = null;
        } else {
            fieldName = null;
            expression = arg.getExpression();
        }

        final String sumName = Calcites.makePrefixedName(name, "sum");
        final String countName = Calcites.makePrefixedName(name, "count");
        final AggregatorFactory sum = SumSqlAggregator.createSumAggregatorFactory(sumType, sumName, fieldName,
                expression, macroTable);

        final AggregatorFactory count = new CountAggregatorFactory(countName);

        return Aggregation.create(ImmutableList.of(sum, count),
                new ArithmeticPostAggregator(name, "quotient",
                        ImmutableList.of(new FieldAccessPostAggregator(null, sumName),
                                new FieldAccessPostAggregator(null, countName))));
    }
}