danny0405 opened a new pull request, #7620:
URL: https://github.com/apache/hudi/pull/7620
At the beginning, we bootstrap the ckp metadata by cleaning all the
messages. This brings in some corner case like 'the write task can not fetch
the pending instant correctly when restartting the job', if a checkpoint
succeed and the job crashes suddenly, the instant hasn't had time to commit,
then the data loss happens, because the last pending instant would be rolled
back, while the Flink engin thinks the checkpint/instant is successful.
Q: Why we clean the messages here ?
A: To prevent inconsistencies between timeline and the messages.
Q: Why we decide to keep the messages ?
A: There are two cases for the inconsistency:
1. the timeline instant is complete but the ckp message is inflight (for
committing instant);
2. the timeline instant is pending while the ckp message does not start (for
starting a new instant);
For case1, there is no need to re-commit the instant, so it's okey the write
task does not get any pending instant when recovering, for case2, the instant
is basically pending, it would be rolled back which is in line with
expectations. so keeping the ckp messages as is can actually maintain
correctness.
### Change Logs
Keep the ckp messages instead of cleaning it.
### Impact
No impact
### Risk level (write none, low medium or high below)
none
### Documentation Update
_Describe any necessary documentation update if there is any new feature,
config, or user-facing change_
- _The config description must be updated if new configs are added or the
default value of the configs are changed_
- _Any new feature or user-facing change requires updating the Hudi website.
Please create a Jira ticket, attach the
ticket number here and follow the
[instruction](https://hudi.apache.org/contribute/developer-setup#website) to
make
changes to the website._
### Contributor's checklist
- [ ] Read through [contributor's
guide](https://hudi.apache.org/contribute/how-to-contribute)
- [ ] Change Logs and Impact were stated clearly
- [ ] Adequate tests were added if applicable
- [ ] CI passed
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