amogh-jahagirdar commented on code in PR #4578:
URL: https://github.com/apache/iceberg/pull/4578#discussion_r867546130
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core/src/main/java/org/apache/iceberg/RemoveSnapshots.java:
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@@ -161,21 +173,101 @@ public List<Snapshot> apply() {
private TableMetadata internalApply() {
this.base = ops.refresh();
+ if (base.refs().isEmpty()) {
+ return base;
+ }
Set<Long> idsToRetain = Sets.newHashSet();
- List<Long> ancestorIds = SnapshotUtil.ancestorIds(base.currentSnapshot(),
base::snapshot);
- if (minNumSnapshots >= ancestorIds.size()) {
- idsToRetain.addAll(ancestorIds);
- } else {
- idsToRetain.addAll(ancestorIds.subList(0, minNumSnapshots));
+ // Identify refs that should be removed
+ Set<String> retainedRefs = computeRetainedRefs(base.refs());
+ Set<Long> retainedRefIds = retainedRefs.stream()
+ .map(ref -> base.ref(ref).snapshotId())
+ .collect(Collectors.toSet());
+
+ for (long idToRemove : idsToRemove) {
+ Preconditions.checkArgument(!retainedRefIds.contains(idToRemove),
+ "Cannot expire %s. There is a reference to it", idToRemove);
+ }
+
+ idsToRetain.addAll(retainedRefIds);
+ Set<Long> branchSnapshotsToRetain =
computeAllBranchSnapshotsToRetain(base.refs());
+ idsToRetain.addAll(branchSnapshotsToRetain);
+ TableMetadata.Builder updatedMetaBuilder = TableMetadata.buildFrom(base);
+ idsToRemove.addAll(base.snapshots().stream().map(Snapshot::snapshotId)
+ .filter(snapshot ->
!idsToRetain.contains(snapshot)).collect(Collectors.toSet()));
+ base.refs().keySet().stream().filter(ref ->
!retainedRefs.contains(ref)).forEach(updatedMetaBuilder::removeRef);
+ updatedMetaBuilder.removeSnapshots(idsToRemove);
+ TableMetadata updatedMetadata = updatedMetaBuilder.build();
+ return updatedMetadata;
+ }
+
+ private boolean multipleLineages(TableMetadata metadata) {
+ List<Snapshot> allSnapshots = metadata.snapshots();
+ Set<Snapshot> mainSnapshots = Sets.newHashSet(SnapshotUtil.ancestorsOf(
+ metadata.ref(SnapshotRef.MAIN_BRANCH).snapshotId(),
metadata::snapshot));
+ return allSnapshots.stream()
+ .filter(snapshot -> !mainSnapshots.contains(snapshot))
+ .filter(snapshot -> snapshot.parentId() != null)
+ .filter(snapshot -> metadata.snapshot(snapshot.parentId()) == null ||
+ !mainSnapshots.contains(metadata.snapshot(snapshot.parentId())))
+ .findAny().isPresent();
Review Comment:
This should filter out any snapshots which are outside the main lineage,
which are not staged commits off of main. Staged commits would have parent
snapshots, and those parent snapshots would be on main.
The existence of a snapshot which does have a parent snapshot, but that
parent snapshot either exists outside of main OR that snapshot no longer exists
means the procedure with cleanExpired cannot be performed. This means there is
a detached commit lineage. @rdblue let me know if I am missing something in my
reasoning.
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