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https://issues.apache.org/jira/browse/SPARK-24385?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Wenchen Fan updated SPARK-24385:
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Fix Version/s: 2.3.2
> Trivially-true EqualNullSafe should be handled like EqualTo in Dataset.join
> ---------------------------------------------------------------------------
>
> Key: SPARK-24385
> URL: https://issues.apache.org/jira/browse/SPARK-24385
> Project: Spark
> Issue Type: Bug
> Components: SQL
> Affects Versions: 2.2.1, 2.3.0
> Reporter: Daniel Shields
> Assignee: Marco Gaido
> Priority: Major
> Fix For: 2.3.2, 2.4.0
>
>
> Dataset.join(right: Dataset[_], joinExprs: Column, joinType: String) has
> special logic for resolving trivially-true predicates to both sides. It
> currently handles regular equals but not null-safe equals; the code should be
> updated to also handle null-safe equals.
> Pyspark example:
> {code:java}
> df = spark.range(10)
> df.join(df, 'id').collect() # This works.
> df.join(df, df['id'] == df['id']).collect() # This works.
> df.join(df, df['id'].eqNullSafe(df['id'])).collect() # This fails!!!
> # This is a workaround that works.
> df2 = df.withColumn('id', F.col('id'))
> df.join(df2, df['id'].eqNullSafe(df2['id'])).collect(){code}
> The relevant code in Dataset.join should look like this:
> {code:java}
> // Otherwise, find the trivially true predicates and automatically resolves
> them to both sides.
> // By the time we get here, since we have already run analysis, all
> attributes should've been
> // resolved and become AttributeReference.
> val cond = plan.condition.map { _.transform {
> case catalyst.expressions.EqualTo(a: AttributeReference, b:
> AttributeReference) if a.sameRef(b) =>
> catalyst.expressions.EqualTo(
> withPlan(plan.left).resolve(a.name),
> withPlan(plan.right).resolve(b.name))
> // This case is new!!!
> case catalyst.expressions.EqualNullSafe(a: AttributeReference, b:
> AttributeReference) if a.sameRef(b) =>
> catalyst.expressions.EqualNullSafe(
> withPlan(plan.left).resolve(a.name),
> withPlan(plan.right).resolve(b.name))
> }}
> {code}
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