flyrain commented on code in PR #3415:
URL: https://github.com/apache/polaris/pull/3415#discussion_r2689031469
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runtime/service/src/main/java/org/apache/polaris/service/task/TableCleanupTaskHandler.java:
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@@ -160,13 +213,14 @@ private Stream<TaskEntity> getManifestTaskStream(
// read the manifest list for each snapshot. dedupe the manifest files and
schedule a
// cleanupTask
// for each manifest file and its data files to be deleted
+ // Use a Set to track seen paths for deduplication without materializing
all ManifestFile
+ // objects
+ Set<String> seenPaths = new HashSet<>();
return tableMetadata.snapshots().stream()
.flatMap(sn -> sn.allManifests(fileIO).stream())
- // distinct by manifest path, since multiple snapshots will contain
the same
- // manifest
- .collect(Collectors.toMap(ManifestFile::path, Function.identity(),
(mf1, mf2) -> mf1))
- .values()
- .stream()
+ // distinct by manifest path, since multiple snapshots will contain
the same manifest
+ // Use stateful filter to dedupe while streaming
+ .filter(mf -> seenPaths.add(mf.path()))
.filter(mf -> TaskUtils.exists(mf.path(), fileIO))
Review Comment:
Once we call `.collect(Collectors.toSet()`, the stream is fully
materialized, which will lose the benefit of lazy execution. Here we are trying
lower the memory footprint based on lazy execution.
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