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https://issues.apache.org/jira/browse/SPARK-27581?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Wenchen Fan reassigned SPARK-27581:
-----------------------------------
Assignee: Liang-Chi Hsieh
> DataFrame countDistinct("*") fails with AnalysisException: "Invalid usage of
> '*' in expression 'count'"
> -------------------------------------------------------------------------------------------------------
>
> Key: SPARK-27581
> URL: https://issues.apache.org/jira/browse/SPARK-27581
> Project: Spark
> Issue Type: Bug
> Components: SQL
> Affects Versions: 2.4.0
> Reporter: Josh Rosen
> Assignee: Liang-Chi Hsieh
> Priority: Major
> Fix For: 3.0.0
>
>
> If I have a DataFrame then I can use {{count("*")}} as an expression, e.g.:
> {code:java}
> import org.apache.spark.sql.functions._
> val df = sql("select id % 100 from range(100000)")
> df.select(count("*")).first()
> {code}
> However, if I try to do the same thing with {{countDistinct}} I get an error:
> {code:java}
> import org.apache.spark.sql.functions._
> val df = sql("select id % 100 from range(100000)")
> df.select(countDistinct("*")).first()
> org.apache.spark.sql.AnalysisException: Invalid usage of '*' in expression
> 'count';
> {code}
> As a workaround, I need to use {{expr}}, e.g.
> {code:java}
> import org.apache.spark.sql.functions._
> val df = sql("select id % 100 from range(100000)")
> df.select(expr("count(distinct(*))")).first()
> {code}
> You might be wondering "why not just use {{df.count()}} or
> {{df.distinct().count()}}?" but in my case I'd ultimately to compute both
> counts as part of the same aggregation, e.g.
> {code:java}
> val (cnt, distinctCnt) = df.select(count("*"), countDistinct("*)).as[(Long,
> Long)].first()
> {code}
> I'm reporting this because it's a minor usability annoyance / surprise for
> inexperienced Spark users.
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