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https://issues.apache.org/jira/browse/FLINK-7217?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17328742#comment-17328742
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Flink Jira Bot commented on FLINK-7217:
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This major issue is unassigned and itself and all of its Sub-Tasks have not
been updated for 30 days. So, it has been labeled "stale-major". If this ticket
is indeed "major", please either assign yourself or give an update. Afterwards,
please remove the label. In 7 days the issue will be deprioritized.
> Give hints about unsupported SQL / Table API features.
> ------------------------------------------------------
>
> Key: FLINK-7217
> URL: https://issues.apache.org/jira/browse/FLINK-7217
> Project: Flink
> Issue Type: Improvement
> Components: Table SQL / API
> Reporter: Fabian Hueske
> Priority: Major
> Labels: stale-major
>
> The Table API and SQL do not support every type of query. While being valid
> SQL, we cannot translate certain queries into execution plans. Especially,
> the supported syntax of streaming queries is limited and will probably always
> be limited.
> Therefore it is important to explain a user why a query could not be
> translated. The problem here is that we need to wait for the optimizer to
> explore the full search space and apply all transformation rules before we
> can tell the user that the query could not be translated. Hence, we cannot
> simply throw an exception if a rule cannot be applied, because another rule
> might succeed. If we throw an exception in the optimizer, we would kill the
> exploration and miss a valid plan. However, after the optimizer failed, we
> are missing the complete context and cannot provide valuable feedback beyond
> "query uses an unsupported feature".
> We should try to improve the situation and provide better feedback to users.
> One approach would be that rules collect possible reasons why they could not
> be applied and these reasons are returned to the user when the translation
> fails.
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