[jira] [Created] (SPARK-36996) fixing "SQL column nullable setting not retained as part of spark read" issue

["Senthil Kumar (Jira)" <ji...@apache.org>]

Senthil Kumar created SPARK-36996:
-------------------------------------

             Summary: fixing "SQL column nullable setting not retained as part of spark read" issue
                 Key: SPARK-36996
                 URL: https://issues.apache.org/jira/browse/SPARK-36996
             Project: Spark
          Issue Type: Improvement
          Components: SQL
    Affects Versions: 3.1.2, 3.1.1, 3.1.0, 3.0.0
            Reporter: Senthil Kumar


Sql 'nullable' columns are not retaining 'nullable' type as it is while reading from Spark read using jdbc format.

 

SQL :

------------

 

mysql> CREATE TABLE Persons(Id int NOT NULL, FirstName varchar(255), LastName varchar(255), Age int);

 

mysql> desc Persons;
+-----------+--------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-----------+--------------+------+-----+---------+-------+
| Id | int | NO | | NULL | |
| FirstName | varchar(255) | YES | | NULL | |
| LastName | varchar(255) | YES | | NULL | |
| Age | int | YES | | NULL | |
+-----------+--------------+------+-----+---------+-------+

 

But in Spark  we get all the columns as "Nullable":

=============

scala> val df = spark.read.format("jdbc").option("database","Test_DB").option("user", "root").option("password", "").option("driver", "com.mysql.cj.jdbc.Driver").option("url", "jdbc:mysql://localhost:3306/Test_DB").option("dbtable", "Persons").load()
df: org.apache.spark.sql.DataFrame = [Id: int, FirstName: string ... 2 more fields]

scala> df.printSchema()
root
 |-- Id: integer (nullable = true)
 |-- FirstName: string (nullable = true)
 |-- LastName: string (nullable = true)
 |-- Age: integer (nullable = true)

=============

 



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