TengHuo commented on code in PR #6733:
URL: https://github.com/apache/hudi/pull/6733#discussion_r1009158080
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hudi-flink-datasource/hudi-flink/src/main/java/org/apache/hudi/sink/compact/CompactionPlanOperator.java:
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@@ -129,9 +128,6 @@ private void scheduleCompaction(HoodieFlinkTable<?> table,
long checkpointId) th
List<CompactionOperation> operations =
compactionPlan.getOperations().stream()
.map(CompactionOperation::convertFromAvroRecordInstance).collect(toList());
LOG.info("Execute compaction plan for instant {} as {} file groups",
compactionInstantTime, operations.size());
- WriteMarkersFactory
- .get(table.getConfig().getMarkersType(), table,
compactionInstantTime)
- .deleteMarkerDir(table.getContext(),
table.getConfig().getMarkersDeleteParallelism());
Review Comment:
In this `HoodieMergeHandle.init` method, it will call a method
`createMarkerFile` to create a marker file for the new data file when doing the
compaction. So every marker file represents a new base file.
https://github.com/apache/hudi/blob/efe553b327bc025d242afa37221a740dca9b1ea6/hudi-client/hudi-client-common/src/main/java/org/apache/hudi/io/HoodieMergeHandle.java#L201
In this method `HoodieTable.reconcileAgainstMarkers`, it will delete all
data files which have marker files, but not in `List<HoodieWriteStat> stats`.
https://github.com/apache/hudi/blob/4f6f15c3c761621eaaa1b3b52e0c2841626afe53/hudi-client/hudi-client-common/src/main/java/org/apache/hudi/table/HoodieTable.java#L674
In summary, `WriteMarkers` contains all data files we created in the current
batch (and previous failed batches for the same instant),
`List<HoodieWriteStat> stats` contains all data files we committed in the
current batch.
So, `Set(invalidDataPaths)` = `Set(data file in WriteMarkers)` - `Set(data
file in List<HoodieWriteStat> stats)`
In Hudi Flink online compaction, if there is anything wrong in compaction,
it will do the retry automatically (won't restart the whole pipeline, only
retry compaction). **So If we delete the marker file directory here, it is not
possible to delete the files left by a previous failed compaction (a failed
compaction with same instant), because all their marker files are deleted.**
These un-committed data files will cause `corrupted data file exception` in
future.
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