[jira] [Assigned] (DRILL-5929) Misleading error for text file with blank line delimiter

["Paul Rogers (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/DRILL-5929?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Paul Rogers reassigned DRILL-5929:
----------------------------------

    Assignee: Paul Rogers

> Misleading error for text file with blank line delimiter
> --------------------------------------------------------
>
>                 Key: DRILL-5929
>                 URL: https://issues.apache.org/jira/browse/DRILL-5929
>             Project: Apache Drill
>          Issue Type: Bug
>    Affects Versions: 1.11.0
>            Reporter: Paul Rogers
>            Assignee: Paul Rogers
>            Priority: Minor
>
> Consider the following functional test query:
> {code}
> select * from table(`table_function/colons.txt`(type=>'text',lineDelimiter=>'\\'))
> {code}
> 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}}:
> {code}
> class TextInput ...
>   public final byte nextChar() throws IOException {
>     if (byteChar == lineSeparator[0]) { // but, lineSeparator.length == 0
> {code}
> We then translate the exception:
> {code}
> 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
>           .dataReadError(ex)
>           .message(
>               "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.",
>               MAXIMUM_NUMBER_COLUMNS)
>           .build(logger);
>     }
> {code}
> 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:
> {code}
>   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())
>           .build(logger);
> {code}
> 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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