| /* |
| * 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.phoenix.expression.function; |
| |
| import java.util.List; |
| |
| import org.apache.hadoop.conf.Configuration; |
| import org.apache.hadoop.hbase.io.ImmutableBytesWritable; |
| import org.apache.phoenix.expression.Expression; |
| import org.apache.phoenix.expression.aggregator.Aggregator; |
| import org.apache.phoenix.expression.aggregator.DistinctCountClientAggregator; |
| import org.apache.phoenix.expression.aggregator.DistinctValueWithCountServerAggregator; |
| import org.apache.phoenix.parse.DistinctCountParseNode; |
| import org.apache.phoenix.parse.FunctionParseNode.Argument; |
| import org.apache.phoenix.parse.FunctionParseNode.BuiltInFunction; |
| import org.apache.phoenix.schema.ComparisonNotSupportedException; |
| import org.apache.phoenix.schema.tuple.Tuple; |
| import org.apache.phoenix.schema.types.PDataType; |
| import org.apache.phoenix.schema.types.PLong; |
| import org.apache.phoenix.util.SchemaUtil; |
| |
| |
| /** |
| * |
| * Built-in function for {@code COUNT(distinct <expression>) } aggregate function, |
| * |
| * |
| * @since 1.2.1 |
| */ |
| @BuiltInFunction(name=DistinctCountAggregateFunction.NAME, nodeClass=DistinctCountParseNode.class, args= {@Argument()} ) |
| public class DistinctCountAggregateFunction extends DelegateConstantToCountAggregateFunction { |
| public static final String NAME = "DISTINCT_COUNT"; |
| public static final String NORMALIZED_NAME = SchemaUtil.normalizeIdentifier(NAME); |
| public final static byte[] ZERO = PLong.INSTANCE.toBytes(0L); |
| public final static byte[] ONE = PLong.INSTANCE.toBytes(1L); |
| |
| public DistinctCountAggregateFunction() { |
| } |
| |
| public DistinctCountAggregateFunction(List<Expression> childExpressions) { |
| this(childExpressions, null); |
| } |
| |
| public DistinctCountAggregateFunction(List<Expression> childExpressions, |
| CountAggregateFunction delegate) { |
| super(childExpressions, delegate); |
| assert childExpressions.size() == 1; |
| } |
| |
| @Override |
| public int hashCode() { |
| return isConstantExpression() ? 0 : super.hashCode(); |
| } |
| |
| /** |
| * The COUNT function never returns null |
| */ |
| @Override |
| public boolean isNullable() { |
| return false; |
| } |
| |
| @Override |
| public boolean equals(Object obj) { |
| if (this == obj) return true; |
| if (obj == null) return false; |
| if (getClass() != obj.getClass()) return false; |
| DistinctCountAggregateFunction other = (DistinctCountAggregateFunction)obj; |
| return (isConstantExpression() && other.isConstantExpression()) || children.equals(other.getChildren()); |
| } |
| |
| @Override |
| public PDataType getDataType() { |
| return PLong.INSTANCE; |
| } |
| |
| @Override |
| public DistinctCountClientAggregator newClientAggregator() { |
| return new DistinctCountClientAggregator(getAggregatorExpression().getSortOrder()); |
| } |
| |
| @Override |
| public Aggregator newServerAggregator(Configuration conf) { |
| return new DistinctValueWithCountServerAggregator(conf); |
| } |
| |
| @Override |
| public boolean evaluate(Tuple tuple, ImmutableBytesWritable ptr) { |
| for (Expression child : getChildren()) { |
| if (child.getDataType() != null && !child.getDataType().isComparisonSupported()) { |
| throw new ComparisonNotSupportedException(child.getDataType()); |
| } |
| } |
| // TODO: optimize query plan of this to run scan serially for a limit of one row |
| if (!super.evaluate(tuple, ptr)) { |
| ptr.set(ZERO); // If evaluate returns false, then no rows were found, so result is 0 |
| } else if (isConstantExpression()) { |
| ptr.set(ONE); // Otherwise, we found one or more rows, so a distinct on a constant is 1 |
| } |
| return true; // Always evaluates to a LONG value |
| } |
| |
| @Override |
| public String getName() { |
| return NAME; |
| } |
| |
| @Override |
| public Aggregator newServerAggregator(Configuration config, ImmutableBytesWritable ptr) { |
| DistinctCountClientAggregator clientAgg = newClientAggregator(); |
| clientAgg.aggregate(null, ptr); |
| return new DistinctValueWithCountServerAggregator(config, clientAgg); |
| } |
| } |