comphead commented on code in PR #7250: URL: https://github.com/apache/datafusion-comet/pull/7250#discussion_r4414768567
########## docs/source/contributor-guide/upgrading_datafusion.md: ########## @@ -0,0 +1,137 @@ +<!-- +Licensed to the Apache Software Foundation (ASF) under one +or more contributor license agreements. See the NOTICE file +distributed with this work for additional information +regarding copyright ownership. The ASF licenses this file +to you under the Apache License, Version 2.0 (the +"License"); you may not use this file except in compliance +with the License. You may obtain a copy of the License at + + http://www.apache.org/licenses/LICENSE-2.0 + +Unless required by applicable law or agreed to in writing, +software distributed under the License is distributed on an +"AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY +KIND, either express or implied. See the License for the +specific language governing permissions and limitations +under the License. +--> + +# Upgrading DataFusion + +A DataFusion major release usually changes APIs Comet calls, often moves to new major versions of +the crates whose types cross DataFusion's API (today Arrow, Parquet and object_store), and sometimes +changes behavior that Comet's tests depend on. So while the next DataFusion major version is in +development, Comet builds against DataFusion `main` on a long-lived upgrade branch, which surfaces +breaks and regressions while there is still time to fix them upstream. + +## The Upgrade Branch + +The upgrade to DataFusion N lives on a branch named `datafusion-N` (for example, `datafusion-56`) +in `apache/datafusion-comet` itself, not on a fork, so any committer can push to it. One draft pull +request from that branch to `main` carries the upgrade, titled `deps: upgrade to DataFusion N.0.0`. +It stays a draft until DataFusion N.0.0 is released (see [Merging the Upgrade](#merging-the-upgrade)). + +An EPIC issue titled `DataFusion N upgrade` tracks the upgrade, with each regression it finds as a +sub-issue. The pull request links the EPIC. + +Keep the branch as a small number of commits on top of current `main`, so the pull request shows +only the upgrade. Updating it means resetting onto `main` and force pushing, as described in +[Submitting a Pull Request](development.md#submitting-a-pull-request). Review Comment: Resetting a branch that any committer can push to loses work in a way `--force-with-lease` does not catch. After a plain `git fetch`, the lease compares against the ref just fetched, so a commit another committer pushed in the meantime is dropped unless the person resetting carries it over on purpose. Could this section say how pushers coordinate, for example by announcing the reset on the EPIC and asking for pending commits to be rebased onto the new head? Another option is to update the branch by merging `main` and to squash only when the upgrade merges, which the squash merge already does for `main`. -- 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. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
