org.apache.flink.table.sources.LimitableTableSource.scala Maven / Gradle / Ivy

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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
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 */

package org.apache.flink.table.sources

/**
  * Adds support for limiting push-down to a [[TableSource]].
  * A [[TableSource]] extending this interface is able to limit the number of records.
  */
trait LimitableTableSource {

  /**
   * Check and push down the limit to the table source.
   *
   * @param limit the value which limit the number of records.
   * @return A new cloned instance of [[TableSource]]
   */
  def applyLimit(limit: Long): TableSource

  /**
    * Return the flag to indicate whether limit push down has been tried. Must return true on
    * the returned instance of [[applyLimit]].
    */
  def isLimitPushedDown: Boolean
}