[jira] [Updated] (DRILL-5662) Compliant text reader (CSV) opens, closes, reopens file with headers

["Khurram Faraaz (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/DRILL-5662?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Khurram Faraaz updated DRILL-5662:
----------------------------------
    Component/s: Storage - Text & CSV

> Compliant text reader (CSV) opens, closes, reopens file with headers
> --------------------------------------------------------------------
>
>                 Key: DRILL-5662
>                 URL: https://issues.apache.org/jira/browse/DRILL-5662
>             Project: Apache Drill
>          Issue Type: Bug
>          Components: Storage - Text & CSV
>    Affects Versions: 1.10.0
>            Reporter: Paul Rogers
>            Assignee: Paul Rogers
>            Priority: Minor
>             Fix For: Future
>
>
> The "compliant" (CSV) reader can optional read headers from a file. To do so, the reader:
> * Opens the input stream
> * Reads headers
> * Closes the input stream
> * Opens the input stream
> * Reads data (skipping headers)
> * Closes the input stream
> While the above certainly works, it has an unnecessary close/open cycle. Many CSV readers simply read the header and use the same stream to read data. Drill should do so also.
> In fact, Drill has historically coded its own headers scanner. The first was badly broken, but DRILL-5498 improved the parsing (though not file handling.)
> Given that Drill's "compliant" text reader is based on the UniVocity library, and that library can parse headers, we should probably just reuse that existing code which has, very likely, evolved to handle the header usages seen in the wild.



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