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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
* limitations under the License.
*/
package org.apache.flink.table.api;
import org.apache.flink.annotation.PublicEvolving;
import org.apache.flink.table.expressions.Expression;
import org.apache.flink.table.expressions.ExpressionParser;
/**
* Helper class for creating a sliding window. Sliding windows have a fixed size and slide by
* a specified slide interval. If the slide interval is smaller than the window size, sliding
* windows are overlapping. Thus, an element can be assigned to multiple windows.
*
* For example, a sliding window of size 15 minutes with 5 minutes sliding interval groups
* elements of 15 minutes and evaluates every five minutes. Each element is contained in three
* consecutive window evaluations.
*
*
Java Example:
*
*
* {@code
* Slide.over("10.minutes").every("5.minutes").on("rowtime").as("w")
* }
*
*
* Scala Example:
*
*
* {@code
* Slide over 10.minutes every 5.minutes on 'rowtime as 'w
* }
*
*/
@PublicEvolving
public final class Slide {
/**
* Creates a sliding window. Sliding windows have a fixed size and slide by
* a specified slide interval. If the slide interval is smaller than the window size, sliding
* windows are overlapping. Thus, an element can be assigned to multiple windows.
*
* For example, a sliding window of size 15 minutes with 5 minutes sliding interval groups
* elements of 15 minutes and evaluates every five minutes. Each element is contained in three
* consecutive window evaluations.
*
* @param size the size of the window as time or row-count interval
* @return a partially specified sliding window
*/
public static SlideWithSize over(String size) {
return over(ExpressionParser.parseExpression(size));
}
/**
* Creates a sliding window. Sliding windows have a fixed size and slide by
* a specified slide interval. If the slide interval is smaller than the window size, sliding
* windows are overlapping. Thus, an element can be assigned to multiple windows.
*
*
For example, a sliding window of size 15 minutes with 5 minutes sliding interval groups
* elements of 15 minutes and evaluates every five minutes. Each element is contained in three
* consecutive
*
* @param size the size of the window as time or row-count interval
* @return a partially specified sliding window
*/
public static SlideWithSize over(Expression size) {
return new SlideWithSize(size);
}
}