I have a case where I need to read files with lines of the format

```
Field1,Field2,Field3,Field4,Field5,Field6#Field1,Field2,Field3

```

While one way to achive this would be to use a record reader like `KeyValueLineRecordReader` with the separator `#`. But I will have to split the key and value on `,` in my UDF using `String.split` which I feel can slow down the execution.  

 1. Are there any record readers that serve formats of this type?
 2. If one such a record writer doesn't exist, what are my alternatives for reading such a line efficiently?

Input data is ~10GB.