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From twalthr <...@git.apache.org>
Subject [GitHub] flink pull request #2562: [FLINK-4691] [table] Add group-windows for streami...
Date Thu, 06 Oct 2016 11:53:31 GMT
Github user twalthr commented on a diff in the pull request:

    https://github.com/apache/flink/pull/2562#discussion_r82170972
  
    --- Diff: flink-libraries/flink-table/src/main/scala/org/apache/flink/api/table/windows.scala
---
    @@ -0,0 +1,340 @@
    +/*
    + * 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.api.table
    +
    +import org.apache.flink.api.table.expressions.{Expression, ExpressionParser}
    +import org.apache.flink.api.table.plan.logical._
    +
    +/**
    +  * Group-window specification. Group-windows allow aggregates which are computed for
a group of
    +  * elements. A (time or row-count) window is required to bound the infinite input stream
into a
    +  * finite group. Group-windows are evaluated once per group.
    +  */
    +trait GroupWindow {
    +
    +  /**
    +    * Converts an API class to a logical window for planning. This is an internal method.
    +    */
    +  private[flink] def toLogicalWindow: LogicalWindow
    +}
    +
    +/**
    +  * A group-window operating on event-time.
    +  *
    +  * @param timeField defines the time mode for streaming tables and acts as a time attribute
for
    +  *                  batch tables over which the query is evaluated.
    +  */
    +abstract class EventTimeWindow(timeField: Expression) extends GroupWindow {
    +
    +  protected var name: Option[Expression] = None
    +
    +  /**
    +    * Assigns an alias for this window that the following `select()` clause can refer
to in order
    +    * to access window properties such as window start or end time.
    +    *
    +    * @param alias alias for this window
    +    * @return this window
    +    */
    +  def as(alias: Expression): EventTimeWindow = {
    +    this.name = Some(alias)
    +    this
    +  }
    +
    +  /**
    +    * Assigns an alias for this window that the following `select()` clause can refer
to in order
    +    * to access window properties such as window start or end time.
    +    *
    +    * @param alias alias for this window
    +    * @return this window
    +    */
    +  def as(alias: String): EventTimeWindow = as(ExpressionParser.parseExpression(alias))
    +}
    +
    +// ------------------------------------------------------------------------------------------------
    +// Tumbling group-windows
    +// ------------------------------------------------------------------------------------------------
    +
    +/**
    +  * Tumbling group-window. By default, it works on processing-time.
    +  *
    +  * @param size size of the window either as number of rows or interval of milliseconds
    +  */
    +class TumblingWindow(size: Expression) extends GroupWindow {
    +
    +  /**
    +    * Tumbling group-window. By default, it works on processing-time.
    +    *
    +    * @param size size of the window either as number of rows or interval of milliseconds
    +    */
    +  def this(size: String) = this(ExpressionParser.parseExpression(size))
    +
    +  private var alias: Option[Expression] = None
    +
    +  /**
    +    * Defines the time mode for streaming tables and specifies a time attribute for
    +    * batch tables over which the query is evaluated.
    +    *
    +    * @param timeField time mode for streaming tables and time attribute for batch tables
    +    * @return a tumbling group-window on event-time
    +    */
    +  def on(timeField: Expression): TumblingEventTimeWindow =
    +    new TumblingEventTimeWindow(alias, timeField, size)
    +
    +  /**
    +    * Defines the time mode for streaming tables and specifies a time attribute for
    +    * batch tables over which the query is evaluated.
    +    *
    +    * @param timeField time mode for streaming tables and time attribute for batch tables
    +    * @return a tumbling group-window on event-time
    +    */
    +  def on(timeField: String): TumblingEventTimeWindow =
    +    on(ExpressionParser.parseExpression(timeField))
    +
    +  /**
    +    * Assigns an alias for this window that the following `select()` clause can refer
to in order
    +    * to access window properties such as window start or end time.
    +    *
    +    * @param alias alias for this window
    +    * @return this window
    +    */
    +  def as(alias: Expression): TumblingWindow = {
    +    this.alias = Some(alias)
    +    this
    +  }
    +
    +  /**
    +    * Assigns an alias for this window that the following `select()` clause can refer
to in order
    +    * to access window properties such as window start or end time.
    +    *
    +    * @param alias alias for this window
    +    * @return this window
    +    */
    +  def as(alias: String): TumblingWindow = as(ExpressionParser.parseExpression(alias))
    +
    +  override private[flink] def toLogicalWindow: LogicalWindow =
    +    ProcessingTimeTumblingGroupWindow(alias, size)
    +}
    +
    +/**
    +  * Tumbling group-window on event-time.
    +  */
    +class TumblingEventTimeWindow(
    +    alias: Option[Expression],
    +    time: Expression,
    +    size: Expression)
    +  extends EventTimeWindow(time) {
    +
    +  override private[flink] def toLogicalWindow: LogicalWindow =
    +    EventTimeTumblingGroupWindow(name.orElse(alias), time, size)
    +}
    +
    +// ------------------------------------------------------------------------------------------------
    +// Sliding group windows
    +// ------------------------------------------------------------------------------------------------
    +
    +/**
    +  * Partially specified sliding window.
    +  *
    +  * @param size size of the window either as number of rows or interval of milliseconds
    +  */
    +class SlideWithSize(size: Expression) {
    +
    +  /**
    +    * Partially specified sliding window.
    +    *
    +    * @param size size of the window either as number of rows or interval of milliseconds
    +    */
    +  def this(size: String) = this(ExpressionParser.parseExpression(size))
    +
    +  /**
    +    * Specifies the window's slide. This is the size of the overlap.
    --- End diff --
    
    Done.


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