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https://issues.apache.org/jira/browse/FLINK-10834?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16681236#comment-16681236
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sunjincheng commented on FLINK-10834:
-------------------------------------
Hi，[~fhueske],
Thanks for your comments！
I think the expected steps performed by *FuncRow('a).flatten()* are:
# FuncRow.eval() output: Row(-1189206469, -1189206469, -1189206469)
# Row(-1189206469, -1189206469, -1189206469).flatten() output : -1189206469,
-1189206469, -1189206469
Our current implementation logic of *FuncRow('a).flatten()* are:
# FuncRow.eval().get(0) outout: -1189206469
# FuncRow.eval().get(1) outout: -151367792
# FuncRow.eval().get(0) outout: 1988676906
So, There are two problems:
# For deterministic function execution performance will be poor;
# Fo non-deterministic function execution result is incorrect；
And I think may be we can fix it by improve our flink implementation logic of
"*flatten()", May be* can find solutions in two places *expandProjectList and*
*CodeGenerator#visitFieldAccess.* Try to reuse the rexCall or reuse codegen
string.
What do you think?
Thanks, Jincheng
> 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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