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https://issues.apache.org/jira/browse/FLINK-10834?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16681180#comment-16681180
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Fabian Hueske commented on FLINK-10834:
---------------------------------------
Do you know what the SQL standard defines for non-deterministic functions (or
how other DBMS handle the situation)?
Should they be evaluated just once per row?
If not, than this behavior might be actually fine.
This might also be a Calcite issue.
> TableAPI flatten() calculated value error
> -----------------------------------------
>
> Key: FLINK-10834
> URL: https://issues.apache.org/jira/browse/FLINK-10834
> Project: Flink
> Issue Type: Bug
> Components: Table API & SQL
> Reporter: sunjincheng
> Assignee: Hequn Cheng
> Priority: Major
> Fix For: 1.7.1
>
>
> We have a UDF as follows:
> {code:java}
> object FuncRow extends ScalarFunction {
> def eval(v: Int): Row = {
> val version = "" + new Random().nextInt()
> val row = new Row(3)
> row.setField(0, version)
> row.setField(1, version)
> row.setField(2, version)
> row
> }
> override def isDeterministic: Boolean = false
> override def getResultType(signature: Array[Class[_]]): TypeInformation[_] =
> Types.ROW(Types.STRING, Types.STRING, Types.STRING)
> }
> {code}
> Do the following Query:
> {code:sql}
> val data = new mutable.MutableList[(Int, Long, String)]
> data.+=((1, 1L, "Hi"))
> val ds = env.fromCollection(data).toTable(tEnv, 'a, 'b,'c)
> .select(FuncRow('a).flatten()).as('v1, 'v2, 'v3)
> {code}
> The result is : -1189206469,-151367792,1988676906
> The result expected by the user should be: v1==v2==v3 .
> It looks the real reason is that there is no result of the reuse in codegen.
>
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