Dandandan edited a comment on pull request #9970: URL: https://github.com/apache/arrow/pull/9970#issuecomment-817946446
> > At least would be best to remove support for sum, as we don't have an absolute zero for timestamps. For average, I think it may make some more sense, but I think the use case seems limited to me. > > @Dandandan -- I just double checked and the IOx project actually has need of `Sum` (and `Avg`) for timestamps due to the semantics of the `Flux` and `InfluxQL` languages. I can implement this functionality for custom user defined aggregates if needed, but I would prefer having the functionality in DataFusion directly so that anyone else can potentially use it too > > I don't really understand the comment about "absolute zero" for timestamps. > > Would it be ok with you if I merged in support for Sum for timestamps? My reaction to enable sum for timestamps was that it depends on the starting/zero value for the value, in this case the UNIX epoch. The result of a addition/sum on timestamp is meaningless as it depends on the choice of the value of zero (1980 + 1980 + 1980 = 2000!?, 1970 + 1970 = 1970!?). When we would change the zero value (to Jan 1 1900 for example), we would totally change the meaning of adding timestamps. If there was an "actual" zero date (like Kelvin for example) summing the values makes sense but there isn't such a thing for timestamps of course. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: us...@infra.apache.org
