[SPARK-24540] Support for multiple character delimiter in Spark CSV read

• Type: Improvement
• Status: Resolved
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 2.3.1
• Fix Version/s: 3.0.0
• Component/s: SQL
• Assignee: Jeff Evans
• Reporter: Ashwin K
• Created: 13/Jun/18 05:02
• Updated: 12/Dec/22 18:11
• Resolved: 15/Oct/19 20:45

Description

Currently, the delimiter option Spark 2.0 to read and split CSV files/data only support a single character delimiter. If we try to provide multiple delimiters, we observer the following error message.

eg: Dataset<Row> df = spark.read().option("inferSchema", "true")
                                                         .option("header", "false")

                                                         .option("delimiter", ", ")
                                                         .csv("C:\test.txt");

Exception in thread "main" java.lang.IllegalArgumentException: Delimiter cannot be more than one character: , 

at org.apache.spark.sql.execution.datasources.csv.CSVUtils$.toChar(CSVUtils.scala:111)
at org.apache.spark.sql.execution.datasources.csv.CSVOptions.<init>(CSVOptions.scala:83)
at org.apache.spark.sql.execution.datasources.csv.CSVOptions.<init>(CSVOptions.scala:39)
at org.apache.spark.sql.execution.datasources.csv.CSVFileFormat.inferSchema(CSVFileFormat.scala:55)
at org.apache.spark.sql.execution.datasources.DataSource$$anonfun$8.apply(DataSource.scala:202)
at org.apache.spark.sql.execution.datasources.DataSource$$anonfun$8.apply(DataSource.scala:202)
at scala.Option.orElse(Option.scala:289)
at org.apache.spark.sql.execution.datasources.DataSource.getOrInferFileFormatSchema(DataSource.scala:201)
at org.apache.spark.sql.execution.datasources.DataSource.resolveRelation(DataSource.scala:392)
at org.apache.spark.sql.DataFrameReader.loadV1Source(DataFrameReader.scala:239)
at org.apache.spark.sql.DataFrameReader.load(DataFrameReader.scala:227)
at org.apache.spark.sql.DataFrameReader.csv(DataFrameReader.scala:596)
at org.apache.spark.sql.DataFrameReader.csv(DataFrameReader.scala:473)

 

Generally, the data to be processed contains multiple character delimiters and presently we need to do a manual data clean up on the source/input file, which doesn't work well in large applications which consumes numerous files.

There seems to be work-around like reading data as text and using the split option, but this in my opinion defeats the purpose, advantage and efficiency of a direct read from CSV file.

 

Issue Links

• is blocked by: SPARK-17967 Support for list or other types as an option for datasources
• links to: GitHub Pull Request #26027