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https://issues.apache.org/jira/browse/FLINK-6232?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16089646#comment-16089646
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ASF GitHub Bot commented on FLINK-6232:
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Github user fhueske commented on the issue:
https://github.com/apache/flink/pull/4324
Hi @hongyuhong, thanks for your feedback!
I agree, passing good error messages to users is important. However, this
is very difficult in the optimizer because the optimizer is exploring different
paths. If we throw an exception in the optimizer, we would kill the exploration
and miss a valid plan. That's why I'm very hesitant to throw exceptions in
rules. However, if the optimizer does not find a valid execution plan, it quits
with an error message that tells the user that no valid plan could be found but
does not point to a particular problem (such as an invalid join condition).
A good solution for this is still needed. Maybe we can collect potential
problems during optimization and provide these when the translation fails.
> Support proctime inner equi-join between two streams in the SQL API
> -------------------------------------------------------------------
>
> Key: FLINK-6232
> URL: https://issues.apache.org/jira/browse/FLINK-6232
> Project: Flink
> Issue Type: Sub-task
> Components: Table API & SQL
> Reporter: hongyuhong
> Assignee: hongyuhong
>
> 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.proctime, o.productId, o.orderId, s.proctime AS shipTime
> FROM Orders AS o
> JOIN Shipments AS s
> ON o.orderId = s.orderId
> AND o.proctime BETWEEN s.proctime AND s.proctime + 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.proctime BETWEEN s.proctime AND s.proctime +
> INTERVAL '1' HOUR}} only can use proctime that is a system attribute, the
> time condition only support bounded time range like {{o.proctime BETWEEN
> s.proctime - INTERVAL '1' HOUR AND s.proctime + INTERVAL '1' HOUR}}, not
> support unbounded like {{o.proctime > s.protime}}, and should include both
> two stream's proctime attribute, {{o.proctime between proctime() and
> proctime() + 1}} should also not be supported.
> This issue includes:
> * Design of the DataStream operator to deal with stream join
> * Translation from Calcite's RelNode representation (LogicalJoin).
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