Hi Timo, The messy TableSchema confuses many developers. It's great to see we can finally come up with a clean interface hierarchy and still backward compatible.
Thanks for preparing the nice FLIP. It looks good to me. I have some minor comments: 1) Should `ResolvedSchema#getColumn(int)` returns `TableColumn` instead of `Column`? 2) You mentioned ResolvedSchema should store ResolvedExpression, should we extend `ComputedColumn` and `WatermarkSpec` to allow `ResolvedExpression`? 3) `ResolvedSchema` aims to replace `TableSchema`, it would be better to add un-deprecated methods of `TableSchema` into `ResolvedSchema` (e.g. `getColumnDataTypes()`). Then users can have a smooth migration. Best, Jark On Mon, 8 Feb 2021 at 20:21, Dawid Wysakowicz <dwysakow...@apache.org> wrote: > Hi Timo, > > From my perspective the proposed changes look good. I agree it is an > important step towards FLIP-129 and FLIP-136. Personally I feel > comfortable voting on the document. > > Best, > > Dawid > > On 05/02/2021 16:09, Timo Walther wrote: > > Hi everyone, > > > > you might have seen that we discussed a better schema API in past as > > part of FLIP-129 and FLIP-136. We also discussed this topic during > > different releases: > > > > https://issues.apache.org/jira/browse/FLINK-17793 > > > > Jark and I had an offline discussion how we can finally fix this > > shortcoming and maintain backwards compatibile for a couple of > > releases to give people time to update their code. > > > > I would like to propose the following FLIP: > > > > > https://cwiki.apache.org/confluence/display/FLINK/FLIP-164%3A+Improve+Schema+Handling+in+Catalogs > > > > > > The FLIP updates the class hierarchy to achieve the following goals: > > > > - make it visible whether a schema is resolved or unresolved and when > > the resolution happens > > - offer a unified API for FLIP-129, FLIP-136, and catalogs > > - allow arbitrary data types and expressions in the schema for > > watermark spec or columns > > - have access to other catalogs for declaring a data type or > > expression via CatalogManager > > - a cleaned up TableSchema > > - remain backwards compatible in the persisted properties and API > > > > Looking forward to your feedback. > > > > Thanks, > > Timo > >
