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  1. Apache Drill
  2. DRILL-5929

Misleading error for text file with blank line delimiter



    • Type: Bug
    • Status: Resolved
    • Priority: Minor
    • Resolution: Fixed
    • Affects Version/s: 1.11.0
    • Fix Version/s: 1.17.0
    • Component/s: None
    • Labels:


      Consider the following functional test query:

      select * from table(`table_function/colons.txt`(type=>'text',lineDelimiter=>'\\'))

      For some reason (yet to be determined), when running this from Java, the line delimiter ended up empty. This cases the following line to fail with an ArrayIndexOutOfBoundsException:

      class TextInput ...
        public final byte nextChar() throws IOException {
          if (byteChar == lineSeparator[0]) { // but, lineSeparator.length == 0

      We then translate the exception:

      class TextReader ...
        public final boolean parseNext() throws IOException {
          } catch (Exception ex) {
            try {
              throw handleException(ex);
        private TextParsingException handleException(Exception ex) throws IOException {
          if (ex instanceof ArrayIndexOutOfBoundsException) {
            // Not clear this exception is still thrown...
            ex = UserException
                    "Drill failed to read your text file.  Drill supports up to %d columns in a text file.  Your file appears to have more than that.",

      That is, due to a missing delimiter, we get an index out of bounds exception, which we translate to an error about having too many fields. But, the file itself has only a handful of fields. Thus, the error is completely wrong.

      Then, we compound the error:

        private TextParsingException handleException(Exception ex) throws IOException {
          throw new TextParsingException(context, message, ex);
      class CompliantTextReader ...
        public boolean next() {
          } catch (IOException | TextParsingException e) {
            throw UserException.dataReadError(e)
                .addContext("Failure while reading file %s. Happened at or shortly before byte position %d.",
                  split.getPath(), reader.getPos())

      That is, our AIOB exception became a user exception that became a text parsing exception that became a data read error.

      But, this is not a data read error. It is an error in Drill's own validation logic. Not clear we should be wrapping user exceptions in other errors that we wrap in other user exceptions.


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              • Assignee:
                Paul.Rogers Paul Rogers
                Paul.Rogers Paul Rogers
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                • Created: