Hi Timo, Thanks a lot for the feedback and input. I've added your suggestion to Future Work.
Kind regards, Gustavo On Mon, 9 Nov 2026 at 10:28, Timo Walther via dev <[email protected]> wrote: > Hi Gustavo, > > Thanks for proposing this FLIP. Big +1 for this effort. What others > might not see is that we are still in the learning process of how we > want to use the PTF framework for our built-in functions. Overloading > single functions with too much functionality is definitely an issue that > happened with TO/FROM_CHANGELOG. A TO_APPEND would most likely have > solved 80% of all use cases, and I agree that we should make the most > common case as convenient as possible. > > As an optimization, we might even be able to remove the > ChangelogNormalize if a TO_APPEND immediately follows it. Maybe we can > add this to the Future Work section. > > Thanks, > Timo > > > On 08.11.26 07:20, Gustavo de Morais wrote: > > Hi everyone, > > > > I'd like to propose FLIP-621: Add built-in TO_APPEND PTF [1] for > > discussion. Since we added TO_CHANGELOG, we've seen the same pattern come > > up frequently: users have an updating table and want to write its inserts > > and updates to an append-only sink, dropping deletes. TO_CHANGELOG can do > > this, but it needs an op_mapping that drops deletes plus a projection > that > > removes the op column. > > > > TO_APPEND gives everyone else a very easy way to stay in the append > world, > > without having to understand the changelog behind it. Full signature: > > > > SELECT * FROM TO_APPEND(input => TABLE my_table); > > > > Inserts and updates are emitted as inserts, update-befores and deletes > are > > dropped, and the input schema stays unchanged. Following the PTF > guidelines > > [2], we want to provide functions that solve one problem at a time. > > TO_APPEND fits that well: it is a stateless, row-semantics PTF with an > easy > > to reason implementation. It also covers the use case discussed in the > > mailing list for adding one more parameter to TO_CHANGELOG [3]. Looking > > forward to your feedback and thoughts. > > > > Kind regards, > > Gustavo > > > > [1] > > > https://cwiki.apache.org/confluence/display/FLINK/FLIP-621%3A+Add+built-in+TO_APPEND+PTF > > [2] > > > https://cwiki.apache.org/confluence/spaces/FLINK/pages/462816208/Built-in+Process+Table+Function+Guidelines > > [3] https://lists.apache.org/thread/pfd6ktpyh95j126jm0qolngkrm2bpyhg > >
