This is at analysis time. On Tue, 18 Dec 2018, 17:32 Reynold Xin <r...@databricks.com wrote:
> Is this an analysis time thing or a runtime thing? > > On Tue, Dec 18, 2018 at 7:45 AM Marco Gaido <marcogaid...@gmail.com> > wrote: > >> Hi all, >> >> as you may remember, there was a design doc to support operations >> involving decimals with negative scales. After the discussion in the design >> doc, now the related PR is blocked because for 3.0 we have another option >> which we can explore, ie. forbidding negative scales. This is probably a >> cleaner solution, as most likely we didn't want negative scales, but it is >> a breaking change: so we wanted to check the opinion of the community. >> >> Getting to the topic, here there are the 2 options: >> * - Forbidding negative scales* >> Pros: many sources do not support negative scales (so they can create >> issues); they were something which was not considered as possible in the >> initial implementation, so we get to a more stable situation. >> Cons: some operations which were supported earlier, won't be working >> anymore. Eg. since our max precision is 38, if the scale cannot be negative >> 1e36 * 1e36 would cause an overflow, while now works fine (producing a >> decimal with negative scale); basically impossible to create a config which >> controls the behavior. >> >> *- Handling negative scales in operations* >> Pros: no regressions; we support all the operations we supported on 2.x. >> Cons: negative scales can cause issues in other moments, eg. when >> saving to a data source which doesn't support them. >> >> Looking forward to hear your thoughts, >> Thanks. >> Marco >> >> >>
