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Posted to issues@spark.apache.org by "Hyukjin Kwon (Jira)" <ji...@apache.org> on 2020/02/17 05:05:00 UTC
[jira] [Updated] (SPARK-30847) Take productPrefix into account in
MurmurHash3.productHash
[ https://issues.apache.org/jira/browse/SPARK-30847?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Hyukjin Kwon updated SPARK-30847:
---------------------------------
Description:
See the issue in https://github.com/scala/bug/issues/10495 and fix https://github.com/scala/scala/pull/7648.
Currently, different expressions with same children can produce the same hash as below:
{code}
scala> spark.range(1).selectExpr("id - 1").queryExecution.analyzed.semanticHash()
res0: Int = -565572825
scala> spark.range(1).selectExpr("id + 1").queryExecution.analyzed.semanticHash()
res1: Int = -565572825
{code}
The reason seems to be it doesn't take the product's class itself
was:
Potentially a correctness issue. See the issue in https://github.com/scala/bug/issues/10495 and fix https://github.com/scala/scala/pull/7648.
Currently, different expressions with same children can produce the same hash as below:
{code}
scala> spark.range(1).selectExpr("id - 1").queryExecution.analyzed.semanticHash()
res0: Int = -565572825
scala> spark.range(1).selectExpr("id + 1").queryExecution.analyzed.semanticHash()
res1: Int = -565572825
{code}
The reason seems to be it doesn't take the product's class itself
> Take productPrefix into account in MurmurHash3.productHash
> ----------------------------------------------------------
>
> Key: SPARK-30847
> URL: https://issues.apache.org/jira/browse/SPARK-30847
> Project: Spark
> Issue Type: Bug
> Components: SQL
> Affects Versions: 2.4.5, 3.0.0
> Reporter: Hyukjin Kwon
> Priority: Critical
>
> See the issue in https://github.com/scala/bug/issues/10495 and fix https://github.com/scala/scala/pull/7648.
> Currently, different expressions with same children can produce the same hash as below:
> {code}
> scala> spark.range(1).selectExpr("id - 1").queryExecution.analyzed.semanticHash()
> res0: Int = -565572825
> scala> spark.range(1).selectExpr("id + 1").queryExecution.analyzed.semanticHash()
> res1: Int = -565572825
> {code}
> The reason seems to be it doesn't take the product's class itself
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