[SPARK-17230] Writing decimal to csv will result empty string if the decimal exceeds (20, 18)

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 1.6.2, 2.0.0
• Fix Version/s: 2.0.1, 2.1.0
• Component/s: SQL
• Assignee: Davies Liu
• Reporter: Davies Liu
• Created: 24/Aug/16 20:49
• Updated: 02/Sep/16 22:14
• Resolved: 02/Sep/16 22:14

Description

// file content 
spark.read.csv("/mnt/djiang/test-case.csv").show 
// read in as string and create temp view 
spark.read.csv("/mnt/djiang/test-case.csv").createOrReplaceTempView("test") 
// confirm schema 
spark.table("test").printSchema 
// apply decimal calculation, confirm the result is correct 
spark.sql("select _c0, cast(_c0 as long) * cast('1.0' as decimal(38, 18)) from test").show(false) 
// run the same query, and write out as csv 
spark.sql("select _c0, cast(_c0 as long) * cast('1.0' as decimal(38, 18)) from test").write.csv("/mnt/djiang/test-case-result") 
// show the content of the result file, particularly, for number exceeded decimal(20, 18), the csv is not writing anything or failing silently 
spark.read.csv("/mnt/djiang/test-case-result").show

+------+ 
| _c0| 
+------+ 
| 1| 
| 10| 
| 100| 
| 1000| 
| 10000| 
|100000| 
+------+

root 
|-- _c0: string (nullable = true)

+------+-------------------------------------------------------------------------------------------------------------------------------------------------+ 
|_c0 |(CAST(CAST(CAST(CAST(_c0 AS DECIMAL(20,0)) AS BIGINT) AS DECIMAL(20,0)) AS DECIMAL(38,18)) * CAST(CAST(1.0 AS DECIMAL(38,18)) AS DECIMAL(38,18)))| 
+------+-------------------------------------------------------------------------------------------------------------------------------------------------+ 
|1 |1.000000000000000000 | 
|10 |10.000000000000000000 | 
|100 |100.000000000000000000 | 
|1000 |1000.000000000000000000 | 
|10000 |10000.000000000000000000 |
|100000|100000.000000000000000000 | 
+------+-------------------------------------------------------------------------------------------------------------------------------------------------+

+------+--------------------+ 
| _c0| _c1| 
+------+--------------------+ 
| 1|1.000000000000000000| 
| 10|10.00000000000000...| 
| 100| | 
| 1000| | 
| 10000| | 
|100000| | 
+------+--------------------+

Issue Links

• links to: [Github] Pull Request #14797 (davies)