[
https://issues.apache.org/jira/browse/SPARK-29432?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Hyukjin Kwon updated SPARK-29432:
---------------------------------
Description:
When I add a new column to a dataframe with {{withColumn}} function, by
default, the column is added with {{nullable=false}}.
But, when I save the dataframe, the flag changes to {{nullable=true}}. Is this
the expected behavior? why?
{code}
>>> l = [('Alice', 1)]
>>> df = spark.createDataFrame(l)
>>> df.printSchema()
root
|-- _1: string (nullable = true)
|-- _2: long (nullable = true)
{code}
{code}
>>> from pyspark.sql.functions import lit
>>> df = df.withColumn('newCol', lit('newVal'))
>>> df.printSchema()
root
|-- _1: string (nullable = true)
|-- _2: long (nullable = true)
|-- newCol: string (nullable = false)
>>> spark.sql("select * from default.withcolTest").printSchema()
|-- _1: string (nullable = true)
|-- _2: long (nullable = true)
|-- newCol: string (nullable = true)
{code}
was:
When I add a new column to a dataframe with {{withColumn}} function, by
default, the column is added with {{nullable=false}}.
But, when I save the dataframe, the flag changes to {{nullable=true}}. Is this
the expected behavior? why?
{{>>> l = [('Alice', 1)]}}
{{>>> df = spark.createDataFrame(l)}}
{{>>> df.printSchema()}}
{{root}}
\{{ |-- _1: string (nullable = true)}}
\{{ |-- _2: long (nullable = true)}}
{{>>> from pyspark.sql.functions import lit}}
{{>>> df = df.withColumn('newCol', lit('newVal'))}}
{{>>> df.printSchema()}}
{{root}}
\{{ |-- _1: string (nullable = true)}}
\{{ |-- _2: long (nullable = true)}}
\{{ |-- newCol: string (nullable = false)}}{{>>> spark.sql("select * from
default.withcolTest").printSchema()}}
{{root}}
\{{ |-- _1: string (nullable = true)}}
\{{ |-- _2: long (nullable = true)}}
\{{ |-- newCol: string (nullable = true)}}
> nullable flag of new column changes when persisting a pyspark dataframe
> -----------------------------------------------------------------------
>
> Key: SPARK-29432
> URL: https://issues.apache.org/jira/browse/SPARK-29432
> Project: Spark
> Issue Type: Question
> Components: SQL
> Affects Versions: 2.4.0
> Environment: Spark 2.4.0-cdh6.1.1 (Cloudera distribution)
> Python 3.7.3
> Reporter: Prasanna Saraswathi Krishnan
> Priority: Minor
>
> When I add a new column to a dataframe with {{withColumn}} function, by
> default, the column is added with {{nullable=false}}.
> But, when I save the dataframe, the flag changes to {{nullable=true}}. Is
> this the expected behavior? why?
>
> {code}
> >>> l = [('Alice', 1)]
> >>> df = spark.createDataFrame(l)
> >>> df.printSchema()
> root
> |-- _1: string (nullable = true)
> |-- _2: long (nullable = true)
> {code}
> {code}
> >>> from pyspark.sql.functions import lit
> >>> df = df.withColumn('newCol', lit('newVal'))
> >>> df.printSchema()
> root
> |-- _1: string (nullable = true)
> |-- _2: long (nullable = true)
> |-- newCol: string (nullable = false)
> >>> spark.sql("select * from default.withcolTest").printSchema()
> |-- _1: string (nullable = true)
> |-- _2: long (nullable = true)
> |-- newCol: string (nullable = true)
> {code}
--
This message was sent by Atlassian Jira
(v8.3.4#803005)
---------------------------------------------------------------------
To unsubscribe, e-mail: issues-unsubscr...@spark.apache.org
For additional commands, e-mail: issues-h...@spark.apache.org
