/*
 * 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
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 */

package org.apache.flink.table.sources

/**
  * Adds support for projection push-down to a [[TableSource]].
  * A [[TableSource]] extending this interface is able to project the fields of the return table.
  */
trait ProjectableTableSource {

  /**
    * Creates a copy of the [[TableSource]] that projects its output on the specified fields.
    *
    * @param fields The indexes of the fields to return.
    * @return A copy of the [[TableSource]] that projects its output.
    */
  def projectFields(fields: Array[Int]): TableSource

}