[jira] [Created] (ARROW-7508) DateTime Reading is Broken

[Anthony Abate (Jira)]

Anthony Abate created ARROW-7508:
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             Summary: DateTime Reading is Broken
                 Key: ARROW-7508
                 URL: https://issues.apache.org/jira/browse/ARROW-7508
             Project: Apache Arrow
          Issue Type: Bug
          Components: C#
    Affects Versions: 0.15.1
            Reporter: Anthony Abate
            Assignee: Anthony Abate


DateTime support for writing works - but reading is broken.

This another arithmetic overflow bug (reported a few already) which is causing 
date to be misinterpreted

 

I extracted the current logic out to linqpad and to show the bug and fix:

 
{code:java}
        var dto = DateTimeOffset.Parse("2024-09-25");
        (dto.ToUnixTimeMilliseconds() / 86400000).Dump();
        // YIELDS: 19991
        
        unchecked  (current code)
        {
                DateTimeOffset.FromUnixTimeMilliseconds(19991 * 
86400000).Dump();
                // 1/8/1970 WRONG
        }       

        checked
        {
                DateTimeOffset.FromUnixTimeMilliseconds((long)19991 * 
86400000).Dump();
                // 9/25/2024 CORRECT
        } {code}
 

 

this fix is trivial - a cast to long is missing whereever 
FromUnixTimeMilliseconds is used

 

 



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