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Posted to issues@spark.apache.org by "Sascha Baumanns (Jira)" <ji...@apache.org> on 2020/08/20 09:45:00 UTC
[jira] [Commented] (SPARK-32635) When pyspark.sql.functions.lit()
function is used with dataframe cache, it returns wrong result
[ https://issues.apache.org/jira/browse/SPARK-32635?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17181076#comment-17181076 ]
Sascha Baumanns commented on SPARK-32635:
-----------------------------------------
Please close the brackets in the first code section: final.show()
> When pyspark.sql.functions.lit() function is used with dataframe cache, it returns wrong result
> -----------------------------------------------------------------------------------------------
>
> Key: SPARK-32635
> URL: https://issues.apache.org/jira/browse/SPARK-32635
> Project: Spark
> Issue Type: Bug
> Components: PySpark, SQL
> Affects Versions: 3.0.0
> Reporter: Vinod KC
> Priority: Major
>
> When pyspark.sql.functions.lit() function is used with dataframe cache, it returns wrong result
> eg:lit() function with cache() function.
> -----------------------------------
> {code:java}
> from pyspark.sql import Row
> from pyspark.sql import functions as F
> df_1 = spark.createDataFrame(Row(**x) for x in [{'col1': 'b'}]).withColumn("col2", F.lit(str(2)))
> df_2 = spark.createDataFrame(Row(**x) for x in [{'col1': 'a', 'col3': 8}]).withColumn("col2", F.lit(str(1)))
> df_3 = spark.createDataFrame(Row(**x) for x in [{'col1': 'b', 'col3': 9}]).withColumn("col2", F.lit(str(2)))
> df_23 = df_2.union(df_3)
> df_4 = spark.createDataFrame(Row(**x) for x in [{'col3': 9}]).withColumn("col2", F.lit(str(2)))
> sel_col3 = df_23.select('col3', 'col2')
> df_4 = df_4.join(sel_col3, on=['col3', 'col2'], how = "inner")
> df_23_a = df_23.join(df_1, on=["col1", 'col2'], how="inner").cache()
> finaldf = df_23_a.join(df_4, on=['col2', 'col3'], how='left').filter(F.col('col3') == 9)
> finaldf.show(
> finaldf.select('col2').show() #Wrong result
> {code}
>
> Output
> -----------
> {code:java}
> >>> finaldf.show()
> +----+----+----+
> |col2|col3|col1|
> +----+----+----+
> | 2| 9| b|
> +----+----+----+
> >>> finaldf.select('col2').show() #Wrong result, instead of 2, got 1
> +----+
> |col2|
> +----+
> | 1|
> +----+
> +----+{code}
> lit() function without cache() function.
> {code:java}
> from pyspark.sql import Row
> from pyspark.sql import functions as F
> df_1 = spark.createDataFrame(Row(**x) for x in [{'col1': 'b'}]).withColumn("col2", F.lit(str(2)))
> df_2 = spark.createDataFrame(Row(**x) for x in [{'col1': 'a', 'col3': 8}]).withColumn("col2", F.lit(str(1)))
> df_3 = spark.createDataFrame(Row(**x) for x in [{'col1': 'b', 'col3': 9}]).withColumn("col2", F.lit(str(2)))
> df_23 = df_2.union(df_3)
> df_4 = spark.createDataFrame(Row(**x) for x in [{'col3': 9}]).withColumn("col2", F.lit(str(2)))
> sel_col3 = df_23.select('col3', 'col2')
> df_4 = df_4.join(sel_col3, on=['col3', 'col2'], how = "inner")
> df_23_a = df_23.join(df_1, on=["col1", 'col2'], how="inner")
> finaldf = df_23_a.join(df_4, on=['col2', 'col3'], how='left').filter(F.col('col3') == 9)
> finaldf.show()
> finaldf.select('col2').show() #Correct result
> {code}
>
> Output
> {code:java}
> ----------
> >>> finaldf.show()
> +----+----+----+
> |col2|col3|col1|
> +----+----+----+
> | 2| 9| b|
> +----+----+----+
> >>> finaldf.select('col2').show() #Correct result, when df_23_a is not cached
> +----+
> |col2|
> +----+
> | 2|
> +----+
> {code}
>
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