[jira] [Work started] (HIVE-4884) ORC TimestampTreeReader.nextVector() off by a second when time in fractional

["Gopal V (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/HIVE-4884?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Work on HIVE-4884 started by Gopal V.

> ORC TimestampTreeReader.nextVector() off by a second when time in fractional
> ----------------------------------------------------------------------------
>
>                 Key: HIVE-4884
>                 URL: https://issues.apache.org/jira/browse/HIVE-4884
>             Project: Hive
>          Issue Type: Sub-task
>          Components: File Formats
>    Affects Versions: vectorization-branch
>            Reporter: Gopal V
>            Assignee: Gopal V
>             Fix For: vectorization-branch
>
>         Attachments: HIVE-4884-0000.patch
>
>
> When using negative timestamps, the ORC vectorized Timestampreader does the following
> {code}
> result.vector[i] = (result.vector[i] * 1000000) + nanoVector.vector[i];
> {code}
> This suffers from inaccuracies because the nanoseconds are always positive and the result.vector[i] is in effect 
> {code}
> seconds = (getTime() / 1000)
> nanos = (getNanos())
> // so -42001 ms is written as
> // seconds = -42
> // nanos = 999000000
> // (-42001 / 1000) * 1000 == -42000
> // + 999 ms (from nanos)
> // which is -42999 ms
> {code}
> This needs to be adjusted down if nanos has been zero adjusted, to result in -42001 as the vector[i] value.

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