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From "ASF GitHub Bot (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (FLINK-6233) Support rowtime inner equi-join between two streams in the SQL API
Date Tue, 05 Sep 2017 21:51:09 GMT

    [ https://issues.apache.org/jira/browse/FLINK-6233?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16154401#comment-16154401

ASF GitHub Bot commented on FLINK-6233:

Github user fhueske commented on a diff in the pull request:

    --- Diff: flink-libraries/flink-table/src/main/scala/org/apache/flink/table/runtime/join/WindowJoinUtil.scala
    @@ -115,10 +118,15 @@ object WindowJoinUtil {
           case _ =>
             Some(otherPreds.reduceLeft((l, r) => RelOptUtil.andJoinFilters(rexBuilder,
l, r)))
    -    val bounds = Some(WindowBounds(timePreds.head.isEventTime, leftLowerBound, leftUpperBound))
    -    (bounds, remainCondition)
    +    if (timePreds.head.leftInputOnLeftSide) {
    --- End diff --
    Please replace the condition as follows:
      val bounds = if (timePreds.head.leftInputOnLeftSide) {
      } else {
      (bounds, remainCondition)
    We should not get the right index from the second time predicate because the tables might
be accessed in inverse order there (we would need to check `leftInputOnLeftSide` again).

> Support rowtime inner equi-join between two streams in the SQL API
> ------------------------------------------------------------------
>                 Key: FLINK-6233
>                 URL: https://issues.apache.org/jira/browse/FLINK-6233
>             Project: Flink
>          Issue Type: Sub-task
>          Components: Table API & SQL
>            Reporter: hongyuhong
>            Assignee: Xingcan Cui
> The goal of this issue is to add support for inner equi-join on proc time streams to
the SQL interface.
> Queries similar to the following should be supported:
> {code}
> SELECT o.rowtime , o.productId, o.orderId, s.rowtime AS shipTime 
> FROM Orders AS o 
> JOIN Shipments AS s 
> ON o.orderId = s.orderId 
> AND o.rowtime BETWEEN s.rowtime AND s.rowtime + INTERVAL '1' HOUR;
> {code}
> The following restrictions should initially apply:
> * The join hint only support inner join
> * The ON clause should include equi-join condition
> * The time-condition {{o.rowtime BETWEEN s.rowtime AND s.rowtime + INTERVAL '1' HOUR}}
only can use rowtime that is a system attribute, the time condition only support bounded time
range like {{o.rowtime BETWEEN s.rowtime - INTERVAL '1' HOUR AND s.rowtime + INTERVAL '1'
HOUR}}, not support unbounded like {{o.rowtime &lt; s.rowtime}} ,  and  should include
both two stream's rowtime attribute, {{o.rowtime between rowtime () and rowtime () + 1}} should
also not be supported.
> An row-time streams join will not be able to handle late data, because this would mean
in insert a row into a sorted order shift all other computations. This would be too expensive
to maintain. Therefore, we will throw an error if a user tries to use an row-time stream join
with late data handling.
> This issue includes:
> * Design of the DataStream operator to deal with stream join
> * Translation from Calcite's RelNode representation (LogicalJoin). 

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