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https://issues.apache.org/jira/browse/FLINK-20887?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17262211#comment-17262211
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Leonard Xu commented on FLINK-20887:
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Hi, [~TsReaper]
I think it's not related to the FlinkCalcMergeRule because the plan will not
be matched by the rule and it always fails no matter the FlinkCalcMergeRule is
added or not.
And I think the fail reason is that the RAND() function materialized when it
is used rather than when it is declared.
> Non-deterministic functions return different values even if it is referred
> with the same column name
> ----------------------------------------------------------------------------------------------------
>
> Key: FLINK-20887
> URL: https://issues.apache.org/jira/browse/FLINK-20887
> Project: Flink
> Issue Type: Bug
> Components: Table SQL / Planner
> Affects Versions: 1.13.0
> Reporter: Caizhi Weng
> Priority: Major
>
> Add the following test case to {{CalcITCase.scala}}
> {code:scala}
> @Test
> def testRand(): Unit = {
> checkResult(
> s"""
> |SELECT b - a FROM (
> | SELECT r + 5 AS a, r + 7 AS b FROM (
> | SELECT RAND() AS r FROM SmallTable3
> | ) t1
> |) t2
> |""".stripMargin,
> Seq(row(2), row(2), row(2))
> )
> }
> {code}
> Failure messages are
> {code}
> Results
> == Correct Result - 3 == == Actual Result - 3 ==
> !2 1.051329250417921
> !2 1.3649146677814379
> !2 1.787784536771345
>
> Plan:
> == Abstract Syntax Tree ==
> LogicalProject(EXPR$0=[-($1, $0)])
> +- LogicalProject(a=[+($0, 5)], b=[+($0, 7)])
> +- LogicalProject(r=[RAND()])
> +- LogicalTableScan(table=[[default_catalog, default_database,
> SmallTable3]])
> == Optimized Logical Plan ==
> Calc(select=[-(+(RAND(), 7), +(RAND(), 5)) AS EXPR$0])
> +- BoundedStreamScan(table=[[default_catalog, default_database,
> SmallTable3]], fields=[a, b, c])
> {code}
> It seems that the projections are merged incorrectly. However if you run the
> following test case in {{FlinkCalcMergeRuleTest.scala}}
> {code:scala}
> @Test
> def testCalcMergeWithRandomUdf(): Unit = {
> val sqlQuery = "SELECT ts + a, ts + b FROM " +
> "(SELECT a, b, random_udf(a) AS ts FROM MyTable WHERE a = b) t"
> util.verifyRelPlan(sqlQuery)
> }
> {code}
> The result is
> {code:xml}
> <Root>
> <TestCase name="testCalcMergeWithRandomUdf">
> <Resource name="sql">
> <![CDATA[SELECT ts + a, ts + b FROM (SELECT a, b, random_udf(a) AS ts
> FROM MyTable WHERE a = b) t]]>
> </Resource>
> <Resource name="ast">
> <![CDATA[
> LogicalProject(EXPR$0=[+(random_udf($0), $0)], EXPR$1=[+(random_udf($0), $1)])
> +- LogicalFilter(condition=[=($0, $1)])
> +- LogicalTableScan(table=[[default_catalog, default_database, MyTable,
> source: [TestTableSource(a, b, c)]]])
> ]]>
> </Resource>
> <Resource name="optimized rel plan">
> <![CDATA[
> FlinkLogicalCalc(select=[+(random_udf(a), a) AS EXPR$0, +(random_udf(a), b)
> AS EXPR$1], where=[=(a, b)])
> +- FlinkLogicalLegacyTableSourceScan(table=[[default_catalog,
> default_database, MyTable, source: [TestTableSource(a, b, c)]]], fields=[a,
> b, c])
> ]]>
> </Resource>
> </TestCase>
> </Root>
> {code}
> It seems that the plan is incorrect from the AST. So this seems to be a bug
> in Calcite?
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