singhpk234 commented on code in PR #1285:
URL: https://github.com/apache/polaris/pull/1285#discussion_r2153683238
##########
service/common/src/main/java/org/apache/polaris/service/catalog/iceberg/CatalogHandlerUtils.java:
##########
@@ -433,39 +461,233 @@ protected TableMetadata commit(TableOperations ops,
UpdateTableRequest request)
2.0 /* exponential */)
.onlyRetryOn(CommitFailedException.class)
.run(
- taskOps -> {
+ (taskOps) -> {
TableMetadata base = isRetry.get() ? taskOps.refresh() :
taskOps.current();
- isRetry.set(true);
- // validate requirements
+ TableMetadata.Builder metadataBuilder =
TableMetadata.buildFrom(base);
+ TableMetadata newBase = base;
try {
- request.requirements().forEach(requirement ->
requirement.validate(base));
+ request.requirements().forEach((requirement) ->
requirement.validate(base));
} catch (CommitFailedException e) {
- // wrap and rethrow outside of tasks to avoid unnecessary
retry
- throw new ValidationFailureException(e);
+ if (!isRollbackCompactionEnabled()) {
+ throw new ValidationFailureException(e);
+ }
+ LOGGER.debug(
+ "Attempting to Rollback replace operations for table={},
with current-snapshot-id={}",
+ base.uuid(),
+ base.currentSnapshot().snapshotId());
+ UpdateRequirement.AssertRefSnapshotID assertRefSnapshotId =
+ findAssertRefSnapshotID(request);
+ MetadataUpdate.SetSnapshotRef setSnapshotRef =
findSetSnapshotRefUpdate(request);
+
+ if (assertRefSnapshotId == null || setSnapshotRef == null) {
+ // This implies the request was not trying to add a
snapshot.
+ LOGGER.debug(
+ "Giving up on Rollback replace operations for
table={}, with current-snapshot-id={}, as operation doesn't attempts to add a
single snapshot",
+ base.uuid(),
+ base.currentSnapshot().snapshotId());
+ throw new ValidationFailureException(e);
+ }
+
+ // snapshot-id the client expects the table
current_snapshot_id
+ long expectedCurrentSnapshotId =
assertRefSnapshotId.snapshotId();
+
+ MetadataUpdate.AddSnapshot snapshotToBeAdded =
findAddSnapshotUpdate(request);
+ if (snapshotToBeAdded == null) {
+ // Re-throw if, there's no snapshot data to be added.
+ throw new ValidationFailureException(e);
+ }
+
+ LOGGER.info(
+ "Attempting to Rollback replace operation for table={},
with current-snapshot-id={}, to snapshot={}",
+ base.uuid(),
+ base.currentSnapshot().snapshotId(),
+ snapshotToBeAdded.snapshot().snapshotId());
+
+ List<MetadataUpdate> metadataUpdates =
+ generateUpdatesToRemoveNoopSnapshot(
+ base, expectedCurrentSnapshotId,
setSnapshotRef.name());
+
+ if (metadataUpdates == null || metadataUpdates.isEmpty()) {
+ // Nothing can be done as this implies that there were not
all
+ // No-op snapshots (REPLACE) between
expectedCurrentSnapshotId and
+ // currentSnapshotId. hence re-throw the exception caught.
+ throw new ValidationFailureException(e);
+ }
+ // Set back the ref we wanted to set, back to the snapshot-id
+ // the client is expecting the table to be at.
+ metadataBuilder.setBranchSnapshot(
+ expectedCurrentSnapshotId, setSnapshotRef.name());
+
+ // apply the remove snapshots update in the current metadata.
+ // NOTE: we need to setRef to expectedCurrentSnapshotId
first and then apply
+ // remove, as otherwise the remove will drop the reference.
+ // NOTE: we can skip removing the now orphan base. Its not a
hard requirement.
+ // just something good to do, and not leave for Remove
Orphans.
+ // Ref rolled back update correctly to snapshot to be
committed parent now.
+ metadataUpdates.forEach((update ->
update.applyTo(metadataBuilder)));
+ newBase =
setAppropriateLastSeqNumber(metadataBuilder.build());
+ LOGGER.info(
+ "Successfully roll-backed replace operation for
table={}, with current-snapshot-id={}, to snapshot={}",
+ base.uuid(),
+ base.currentSnapshot().snapshotId(),
+ newBase.currentSnapshot().snapshotId());
}
-
- // apply changes
- TableMetadata.Builder metadataBuilder =
TableMetadata.buildFrom(base);
- request.updates().forEach(update ->
update.applyTo(metadataBuilder));
-
- TableMetadata updated = metadataBuilder.build();
- if (updated.changes().isEmpty()) {
- // do not commit if the metadata has not changed
- return;
+ // double check if the requirements passes now.
+ try {
+ TableMetadata baseWithRemovedSnaps = newBase;
+ request
+ .requirements()
+ .forEach((requirement) ->
requirement.validate(baseWithRemovedSnaps));
+ } catch (CommitFailedException e) {
+ throw new ValidationFailureException(e);
}
- // commit
+ TableMetadata.Builder newMetadataBuilder =
TableMetadata.buildFrom(newBase);
+ request.updates().forEach((update) ->
update.applyTo(newMetadataBuilder));
+ TableMetadata updated = newMetadataBuilder.build();
+ // always commit this
taskOps.commit(base, updated);
});
-
} catch (ValidationFailureException e) {
throw e.wrapped();
}
return ops.current();
}
+ private UpdateRequirement.AssertRefSnapshotID findAssertRefSnapshotID(
+ UpdateTableRequest request) {
+ UpdateRequirement.AssertRefSnapshotID assertRefSnapshotID = null;
+ int total = 0;
+ for (UpdateRequirement requirement : request.requirements()) {
+ if (requirement instanceof UpdateRequirement.AssertRefSnapshotID) {
+ ++total;
+ assertRefSnapshotID = (UpdateRequirement.AssertRefSnapshotID)
requirement;
+ }
+ }
+
+ // if > 1 assertion for refs, then it's not safe to roll back, make this
Noop.
+ return total != 1 ? null : assertRefSnapshotID;
+ }
+
+ private List<MetadataUpdate> generateUpdatesToRemoveNoopSnapshot(
+ TableMetadata base, long expectedCurrentSnapshotId, String
updateRefName) {
+ // find the all the snapshots we want to retain which are not the part of
current branch.
+ Set<Long> idsToRetain = Sets.newHashSet();
+ for (Map.Entry<String, SnapshotRef> ref : base.refs().entrySet()) {
+ String refName = ref.getKey();
+ SnapshotRef snapshotRef = ref.getValue();
+ if (refName.equals(updateRefName)) {
+ continue;
+ }
+ idsToRetain.add(ref.getValue().snapshotId());
+ // Always check the ancestry for both branch and tags
+ // mostly for case where a branch was created and then was dropped
+ // then a tag was created and then rollback happened post that tag
+ // was dropped and branch was re-created on it.
+ for (Snapshot ancestor :
SnapshotUtil.ancestorsOf(snapshotRef.snapshotId(), base::snapshot)) {
+ idsToRetain.add(ancestor.snapshotId());
+ }
+ }
+
+ List<MetadataUpdate> updateToRemoveSnapshot = new ArrayList<>();
+ Long snapshotId = base.ref(updateRefName).snapshotId(); // current tip of
the given branch
+ // ensure this branch has the latest sequence number.
+ long expectedSequenceNumber = base.lastSequenceNumber();
+ Set<Long> snapshotsToRemove = new LinkedHashSet<>();
+ while (snapshotId != null && !Objects.equals(snapshotId,
expectedCurrentSnapshotId)) {
+ Snapshot snap = base.snapshot(snapshotId);
+ // catch un-expected state the commit sequence number are
+ // not continuous can happen for a table with multiple branches.
+ if (expectedSequenceNumber != snap.sequenceNumber()) {
+ LOGGER.debug(
+ "Giving up rolling back table {} to snapshot {}, Sequence Number
are not continuous from {}",
+ base.uuid(),
+ snapshotId,
+ expectedSequenceNumber);
+ break;
+ }
+ if (!isRollbackSnapshot(snap) || idsToRetain.contains(snapshotId)) {
+ // Either encountered a non no-op snapshot or the snapshot is being
referenced by any other
+ // reference either by branch or a tag.
+ LOGGER.debug(
+ "Giving up rolling back table {} to snapshot {}, snapshot to be
removed referenced by another branch or tag ancestor",
+ base.uuid(),
+ snapshotId);
+ break;
+ }
+ snapshotsToRemove.add(snap.snapshotId());
+ snapshotId = snap.parentId();
+ // we need continuous sequence number to correctly rollback
+ expectedSequenceNumber--;
Review Comment:
Its just that it will miss the opportunity to rollback, i think its fine
from correctness POV, but i understand we can handle it, let me see if i can
add that check !
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