rdblue commented on code in PR #4578:
URL: https://github.com/apache/iceberg/pull/4578#discussion_r884920285
##########
core/src/main/java/org/apache/iceberg/RemoveSnapshots.java:
##########
@@ -161,21 +174,89 @@ public List<Snapshot> apply() {
private TableMetadata internalApply() {
this.base = ops.refresh();
+ if (base.snapshots().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
+ Map<String, SnapshotRef> retainedRefs = computeRetainedRefs(base.refs());
+ Map<Long, List<String>> retainedIdToRefs = Maps.newHashMap();
+ for (Map.Entry<String, SnapshotRef> retainedRefEntry :
retainedRefs.entrySet()) {
+ long snapshotId = retainedRefEntry.getValue().snapshotId();
+ retainedIdToRefs.putIfAbsent(snapshotId, Lists.newArrayList());
+ retainedIdToRefs.get(snapshotId).add(retainedRefEntry.getKey());
+ }
+
+ for (long idToRemove : idsToRemove) {
+ List<String> refsForId = retainedIdToRefs.get(idToRemove);
+ Preconditions.checkArgument(refsForId == null,
+ "Cannot expire %s. Still referenced by refs: %s", idToRemove,
refsForId);
}
- TableMetadata updateMeta = base.removeSnapshotsIf(snapshot ->
- idsToRemove.contains(snapshot.snapshotId()) ||
- (snapshot.timestampMillis() < expireOlderThan &&
!idsToRetain.contains(snapshot.snapshotId())));
- List<Snapshot> updateSnapshots = updateMeta.snapshots();
- List<Snapshot> baseSnapshots = base.snapshots();
- return updateSnapshots.size() != baseSnapshots.size() ? updateMeta : base;
+ idsToRetain.addAll(retainedIdToRefs.keySet());
+ Set<Long> branchSnapshotsToRetain =
computeAllBranchSnapshotsToRetain(retainedRefs);
+ 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.containsKey(ref)).forEach(updatedMetaBuilder::removeRef);
+ updatedMetaBuilder.removeSnapshots(idsToRemove);
+ return updatedMetaBuilder.build();
+ }
+
+ private Map<String, SnapshotRef> computeRetainedRefs(Map<String,
SnapshotRef> refs) {
+ Map<String, SnapshotRef> retainedRefs = Maps.newHashMap();
+ retainedRefs.put(SnapshotRef.MAIN_BRANCH,
refs.get(SnapshotRef.MAIN_BRANCH));
Review Comment:
Actually, I think it would be easier to move this inside the loop:
```java
for (Map.Entry<String, SnapshotRef> refEntry : refs.entrySet()) {
String name = refEntry.getKey();
SnapshotRef ref = refEntry.getValue();
if (SnapshotRef.MAIN_BRANCH.equals(name)) {
retainedRefs.put(name, ref);
continue;
}
...
}
```
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