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 * 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,
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 */

package org.apache.flink.table.sources;

import org.apache.flink.annotation.Experimental;

/**
 * Adds support for limiting push-down to a {@link TableSource}.
 * A {@link TableSource} extending this interface is able to limit the number of records.
 *
 * <p>After pushing down, source only needs to try its best to limit the number of output records,
 * but does not need to guarantee that the number must be less than or equal to the limit.
 */
@Experimental
public interface LimitableTableSource<T> {

	/**
	 * Return the flag to indicate whether limit push down has been tried. Must return true on
	 * the returned instance of {@link #applyLimit(long)}.
	 */
	boolean isLimitPushedDown();

	/**
	 * 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 {@link TableSource}.
	 */
	TableSource<T> applyLimit(long limit);
}

Introduce LimitableTableSource for optimizing limit