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https://issues.apache.org/jira/browse/SPARK-25961?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16680152#comment-16680152
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Kris Mok commented on SPARK-25961:
----------------------------------
It looks like the current restriction makes sense, because the expressions in
join condition may eventually be evaluated multiple times depending on which
physical join operator is chosen. It doesn't make a lot of sense to allow
non-deterministic expression directly in the Join operator.
Instead, if we have to support having non-deterministic expression in the join
condition and retain an "evaluated-once" semantic, it'd be better to have a
rule in the Analyzer to extract non-deterministic expressions from the join
condition and put it into a child Project operator on the appropriate side.
[~zengxl] does that make sense to you?
> Random numbers are not supported when handling data skew
> --------------------------------------------------------
>
> Key: SPARK-25961
> URL: https://issues.apache.org/jira/browse/SPARK-25961
> Project: Spark
> Issue Type: Bug
> Components: SQL
> Affects Versions: 2.3.1
> Environment: spark on yarn 2.3.1
> Reporter: zengxl
> Priority: Major
>
> my query sql use two table join,one table join key has null value,i use rand
> value instead of null value,but has error,the error info as follows：
> Error in query: nondeterministic expressions are only allowed in
> Project, Filter, Aggregate or Window, found
>
>
> scan spark source code is
> org.apache.spark.sql.catalyst.analysis.CheckAnalysis check sql, because the
> number of random variables is uncertain, it is prohibited
> case o if o.expressions.exists(!_.deterministic) &&
> !o.isInstanceOf[Project] && !o.isInstanceOf[Filter] &&
> !o.isInstanceOf[Aggregate] && !o.isInstanceOf[Window] =>
> // The rule above is used to check Aggregate operator.
> failAnalysis(
> s"""nondeterministic expressions are only allowed in
> |Project, Filter, Aggregate or Window, found:|
> |${o.expressions.map(_.sql).mkString(",")}|
> |in operator ${operator.simpleString}
> """.stripMargin)|
>
> Is it possible to add Join to this code? It's not yet tested.And whether
> there will be other effects
> case o if o.expressions.exists(!_.deterministic) &&
> !o.isInstanceOf[Project] && !o.isInstanceOf[Filter] &&
> !o.isInstanceOf[Aggregate] && !o.isInstanceOf[Window] +{color:#d04437}&&
> !o.isInstanceOf[Join]{color}+ =>
> // The rule above is used to check Aggregate operator.
> failAnalysis(
> s"""nondeterministic expressions are only allowed in
> |Project, Filter, Aggregate or Window or Join, found:|
> |${o.expressions.map(_.sql).mkString(",")}|
> |in operator ${operator.simpleString}
> """.stripMargin)|
>
> this is my sparksql：
> SELECT
> T1.CUST_NO AS CUST_NO ,
> T3.CON_LAST_NAME AS CUST_NAME ,
> T3.CON_SEX_MF AS SEX_CODE ,
> T3.X_POSITION AS POST_LV_CODE
> FROM tmp.ICT_CUST_RANGE_INFO T1
> LEFT join tmp.F_CUST_BASE_INFO_ALL T3 ON CASE WHEN coalesce(T1.CUST_NO,'')
> ='' THEN concat('cust_no',RAND()) ELSE T1.CUST_NO END = T3.BECIF and
> T3.DATE='20181105'
> WHERE T1.DATE='20181105'
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