Hi Wenchen, thanks for your email. I agree adding doc for decimal type, but I am not sure what you mean speaking of the behavior when writing: we are not performing any automatic casting before writing; if we want to do that, we need a design about it I think.
I am not sure if it makes sense to set a min for it. That would break backward compatibility (for very weird use case), so I wouldn't do that. Thanks, Marco Il giorno lun 7 gen 2019 alle ore 05:53 Wenchen Fan <cloud0...@gmail.com> ha scritto: > I think we need to do this for backward compatibility, and according to > the discussion in the doc, SQL standard allows negative scale. > > To do this, I think the PR should also include a doc for the decimal type, > like the definition of precision and scale(this one > <https://stackoverflow.com/questions/35435691/bigdecimal-precision-and-scale> > looks pretty good), and the result type of decimal operations, and the > behavior when writing out decimals(e.g. we can cast decimal(1, -20) to > decimal(20, 0) before writing). > > Another question is, shall we set a min scale? e.g. shall we allow > decimal(1, -10000000)? > > On Thu, Oct 25, 2018 at 9:49 PM Marco Gaido <marcogaid...@gmail.com> > wrote: > >> Hi all, >> >> a bit more than one month ago, I sent a proposal for handling properly >> decimals with negative scales in our operations. This is a long standing >> problem in our codebase as we derived our rules from Hive and SQLServer >> where negative scales are forbidden, while in Spark they are not. >> >> The discussion has been stale for a while now. No more comments on the >> design doc: >> https://docs.google.com/document/d/17ScbMXJ83bO9lx8hB_jeJCSryhT9O_HDEcixDq0qmPk/edit#heading=h.x7062zmkubwm >> . >> >> So I am writing this e-mail in order to check whether there are more >> comments on it or we can go ahead with the PR. >> >> Thanks, >> Marco >> >
