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https://issues.apache.org/jira/browse/FLINK-22968?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17361370#comment-17361370
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Jark Wu commented on FLINK-22968:
---------------------------------
Hi [~DaChun777], thanks for reporting this, but this is not a bug. Flink does
support consuming DataStream with atomic type, e.g. String. However,
{{toAppendStream()}} only support {{Row}} or POJO as result type. This is
claimed in the Javadoc.
{code}
/**
* Converts the given [[Table]] into an append [[DataStream]] of a specified
type.
*
* The [[Table]] must only have insert (append) changes. If the [[Table]] is
also modified
* by update or delete changes, the conversion will fail.
*
* The fields of the [[Table]] are mapped to [[DataStream]] fields as
follows:
* - [[Row]] and Scala Tuple types: Fields are mapped by position, field
* types must match.
* - POJO [[DataStream]] types: Fields are mapped by field name, field types
must match.
*
* @param table The [[Table]] to convert.
* @tparam T The type of the resulting [[DataStream]].
* @return The converted [[DataStream]].
*/
def toAppendStream[T: TypeInformation](table: Table): DataStream[T]
{code}
You can update your code to use Row as output type,
{{tableEnvironment.toAppendStream[Row](res).print()}}, then the job should be
able to run.
> String type cannot be used when creating Flink SQL
> ---------------------------------------------------
>
> Key: FLINK-22968
> URL: https://issues.apache.org/jira/browse/FLINK-22968
> Project: Flink
> Issue Type: Bug
> Components: Table SQL / API
> Affects Versions: 1.12.3, 1.13.1
> Environment: {color:#FF0000}*Flink-1.13.1 and Flink-1.12.1*{color}
> Reporter: DaChun
> Priority: Blocker
> Attachments: test.scala, this_error.txt
>
>
> When I run the program, the error is as follows:
> The specific error is in this_ error.txt,
> But the error prompts me to write an issue
> Caused by: org.apache.flink.api.common.InvalidProgramException: Table program
> cannot be compiled. This is a bug. Please file an issue.
> It's very easy to read a stream and convert it into a table mode. The generic
> type is string
> Then an error is reported. The code is in test. Scala and the error is in
> this_ error.txt
> But I try to create an entity class by myself, and then assign generics to
> this entity class, and then I can pass it normally,
> Or with row type, do you have to create your own entity class, not with
> string type?
>
>
>
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