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https://issues.apache.org/jira/browse/SPARK-52339?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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ASF GitHub Bot updated SPARK-52339:
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Labels: correctness pull-request-available (was: correctness)
> Relations may appear equal even though they are different
> ---------------------------------------------------------
>
> Key: SPARK-52339
> URL: https://issues.apache.org/jira/browse/SPARK-52339
> Project: Spark
> Issue Type: Bug
> Components: SQL
> Affects Versions: 4.0.0, 3.5.6
> Reporter: Bruce Robbins
> Priority: Major
> Labels: correctness, pull-request-available
>
> For example:
> {noformat}
> // create test data
> val data = Seq((1, 2), (2, 3)).toDF("a", "b")
> data.write.mode("overwrite").csv("/tmp/test")
> val fileList1 = List.fill(2)("/tmp/test")
> val fileList2 = List.fill(3)("/tmp/test")
> val df1 = spark.read.schema("a int, b int").csv(fileList1: _*)
> val df2 = spark.read.schema("a int, b int").csv(fileList2: _*)
> df1.count() // correctly returns 4
> df2.count() // correctly returns 6
> // the following is the same as above, except df1 is persisted
> val df1 = spark.read.schema("a int, b int").csv(fileList1: _*).persist
> val df2 = spark.read.schema("a int, b int").csv(fileList2: _*)
> df1.count() // correctly returns 4
> df2.count() // incorrectly returns 4!!
> {noformat}
> df1 and df2 were created with a different number of paths: df1 has 2, and df2
> has 3. But since the distinct set of root paths is the same (e.g.,
> {{Set("/tmp/test") == Set("/tmp/test"))}}, the two dataframes are considered
> equal. Thus, when df1 is persisted, df2 uses df1's cached plan.
> The same bug also causes inappropriate exchange reuse.
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