org.apache.flink.table.operations.DistinctQueryOperation Maven / Gradle / Ivy

Go to download

Show more of this group Show more artifacts with this name
Show all versions of flink-table-api-java Show documentation

This module contains the Table/SQL API for writing table programs within the table ecosystem using the Java programming language.

There is a newer version: 2.0-preview1

Show newest version

/*
 * 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.flink.table.operations;

import org.apache.flink.annotation.Internal;
import org.apache.flink.table.catalog.ResolvedSchema;

import java.util.Collections;
import java.util.List;

/** Removes duplicated rows of underlying relational operation. */
@Internal
public class DistinctQueryOperation implements QueryOperation {

    private final QueryOperation child;

    public DistinctQueryOperation(QueryOperation child) {
        this.child = child;
    }

    @Override
    public ResolvedSchema getResolvedSchema() {
        return child.getResolvedSchema();
    }

    @Override
    public String asSummaryString() {
        return OperationUtils.formatWithChildren(
                "Distinct", Collections.emptyMap(), getChildren(), Operation::asSummaryString);
    }

    @Override
    public List getChildren() {
        return Collections.singletonList(child);
    }

    @Override
    public  T accept(QueryOperationVisitor visitor) {
        return visitor.visit(this);
    }
}