feat: add UpdateSnapshotReference

src/iceberg/CMakeLists.txt

@@ -88,6 +88,7 @@ set(ICEBERG_SOURCES
     update/update_properties.cc
     update/update_schema.cc
     update/update_sort_order.cc
+    update/update_snapshot_reference.cc
     util/bucket_util.cc
     util/content_file_util.cc
     util/conversions.cc

src/iceberg/meson.build

@@ -108,6 +108,7 @@ iceberg_sources = files(
     'update/update_partition_spec.cc',
     'update/update_properties.cc',
     'update/update_schema.cc',
+    'update/update_snapshot_reference.cc',
     'update/update_sort_order.cc',
     'util/bucket_util.cc',
     'util/content_file_util.cc',

src/iceberg/parquet/parquet_data_util.cc

@@ -148,7 +148,7 @@ Result<std::shared_ptr<::arrow::Array>> ProjectStructArray(
   return output_array;
 }
 
-///  Templated implementation for projecting list arrays.
+/// \brief Templated implementation for projecting list arrays.
 /// Works with both ListArray/ListType (32-bit offsets) and
 /// LargeListArray/LargeListType (64-bit offsets).
 template <typename ArrowListArrayType, typename ArrowListType>

src/iceberg/transaction.cc

@@ -36,6 +36,7 @@
 #include "iceberg/update/update_partition_spec.h"
 #include "iceberg/update/update_properties.h"
 #include "iceberg/update/update_schema.h"
+#include "iceberg/update/update_snapshot_reference.h"
 #include "iceberg/update/update_sort_order.h"
 #include "iceberg/util/checked_cast.h"
 #include "iceberg/util/location_util.h"
@@ -183,6 +184,24 @@ Status Transaction::Apply(PendingUpdate& update) {
         metadata_builder_->RemoveSchemas(std::move(result.schema_ids_to_remove));
       }
     } break;
+    case PendingUpdate::Kind::kUpdateSnapshotReference: {
+      auto& update_ref = internal::checked_cast<UpdateSnapshotReference&>(update);
+      ICEBERG_ASSIGN_OR_RAISE(auto updated_refs, update_ref.Apply());
+      const auto& current_refs = current().refs;
+      // Identify references which have been removed
+      for (const auto& [name, ref] : current_refs) {
+        if (updated_refs.find(name) == updated_refs.end()) {
+          metadata_builder_->RemoveRef(name);
+        }
+      }
+      // Identify references which have been created or updated
+      for (const auto& [name, ref] : updated_refs) {
+        auto current_it = current_refs.find(name);
+        if (current_it == current_refs.end() || *current_it->second != *ref) {
+          metadata_builder_->SetRef(name, ref);
+        }
+      }
+    } break;
     default:
       return NotSupported("Unsupported pending update: {}",
                           static_cast<int32_t>(update.kind()));
@@ -280,4 +299,12 @@ Result<std::shared_ptr<ExpireSnapshots>> Transaction::NewExpireSnapshots() {
   return expire_snapshots;
 }
 
+Result<std::shared_ptr<UpdateSnapshotReference>>
+Transaction::NewUpdateSnapshotReference() {
+  ICEBERG_ASSIGN_OR_RAISE(std::shared_ptr<UpdateSnapshotReference> update_ref,
+                          UpdateSnapshotReference::Make(shared_from_this()));
+  ICEBERG_RETURN_UNEXPECTED(AddUpdate(update_ref));
+  return update_ref;
+}
+
 }  // namespace iceberg

src/iceberg/transaction.h

@@ -82,6 +82,10 @@ class ICEBERG_EXPORT Transaction : public std::enable_shared_from_this<Transacti
   /// changes.
   Result<std::shared_ptr<ExpireSnapshots>> NewExpireSnapshots();
 
+  /// \brief Create a new UpdateSnapshotReference to update snapshot references (branches
+  /// and tags) and commit the changes.
+  Result<std::shared_ptr<UpdateSnapshotReference>> NewUpdateSnapshotReference();
+
  private:
   Transaction(std::shared_ptr<Table> table, Kind kind, bool auto_commit,
               std::unique_ptr<TableMetadataBuilder> metadata_builder);

src/iceberg/type_fwd.h

@@ -194,6 +194,7 @@ class UpdateProperties;
 class UpdateSchema;
 class UpdateSortOrder;
 class ExpireSnapshots;
+class UpdateSnapshotReference;
 
 /// ----------------------------------------------------------------------------
 /// TODO: Forward declarations below are not added yet.

src/iceberg/update/meson.build

@@ -21,6 +21,7 @@ install_headers(
         'snapshot_update.h',
         'update_partition_spec.h',
         'update_schema.h',
+        'update_snapshot_reference.h',
         'update_sort_order.h',
         'update_properties.h',
     ],

src/iceberg/update/pending_update.h

@@ -48,6 +48,7 @@ class ICEBERG_EXPORT PendingUpdate : public ErrorCollector {
     kUpdateSchema,
     kUpdateSnapshot,
     kUpdateSortOrder,
+    kUpdateSnapshotReference,
   };
 
   /// \brief Return the kind of this pending update.

src/iceberg/update/update_snapshot_reference.cc

@@ -0,0 +1,228 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+#include "iceberg/update/update_snapshot_reference.h"
+
+#include <memory>
+#include <optional>
+#include <string>
+#include <unordered_map>
+
+#include "iceberg/result.h"
+#include "iceberg/snapshot.h"
+#include "iceberg/table_metadata.h"
+#include "iceberg/transaction.h"
+#include "iceberg/util/error_collector.h"
+#include "iceberg/util/macros.h"
+#include "iceberg/util/snapshot_util_internal.h"
+
+namespace iceberg {
+
+Result<std::shared_ptr<UpdateSnapshotReference>> UpdateSnapshotReference::Make(
+    std::shared_ptr<Transaction> transaction) {
+  ICEBERG_PRECHECK(transaction != nullptr,
+                   "Cannot create UpdateSnapshotReference without a transaction");
+  return std::shared_ptr<UpdateSnapshotReference>(
+      new UpdateSnapshotReference(std::move(transaction)));
+}
+
+UpdateSnapshotReference::UpdateSnapshotReference(std::shared_ptr<Transaction> transaction)
+    : PendingUpdate(std::move(transaction)) {
+  // Initialize updated_refs_ with current refs from base metadata
+  for (const auto& [name, ref] : base().refs) {
+    updated_refs_[name] = ref;
+  }
+}
+
+UpdateSnapshotReference::~UpdateSnapshotReference() = default;
+
+UpdateSnapshotReference& UpdateSnapshotReference::CreateBranch(const std::string& name,
+                                                               int64_t snapshot_id) {
+  ICEBERG_BUILDER_CHECK(!name.empty(), "Branch name cannot be empty");
+  ICEBERG_BUILDER_ASSIGN_OR_RETURN(auto branch, SnapshotRef::MakeBranch(snapshot_id));
+  auto [_, inserted] = updated_refs_.emplace(name, std::move(branch));
+  ICEBERG_BUILDER_CHECK(inserted, "Ref '{}' already exists", name);
+  return *this;
+}
+
+UpdateSnapshotReference& UpdateSnapshotReference::CreateTag(const std::string& name,
+                                                            int64_t snapshot_id) {
+  ICEBERG_BUILDER_CHECK(!name.empty(), "Tag name cannot be empty");
+  ICEBERG_BUILDER_ASSIGN_OR_RETURN(auto tag, SnapshotRef::MakeTag(snapshot_id));
+  auto [_, inserted] = updated_refs_.emplace(name, std::move(tag));
+  ICEBERG_BUILDER_CHECK(inserted, "Ref '{}' already exists", name);
+  return *this;
+}
+
+UpdateSnapshotReference& UpdateSnapshotReference::RemoveBranch(const std::string& name) {
+  ICEBERG_BUILDER_CHECK(!name.empty(), "Branch name cannot be empty");
+  ICEBERG_BUILDER_CHECK(name != SnapshotRef::kMainBranch, "Cannot remove main branch");
+  auto it = updated_refs_.find(name);
+  ICEBERG_BUILDER_CHECK(it != updated_refs_.end(), "Branch does not exist: {}", name);
+  ICEBERG_BUILDER_CHECK(it->second->type() == SnapshotRefType::kBranch,
+                        "Ref '{}' is a tag not a branch", name);
+  updated_refs_.erase(it);
+  return *this;
+}
+
+UpdateSnapshotReference& UpdateSnapshotReference::RemoveTag(const std::string& name) {
+  ICEBERG_BUILDER_CHECK(!name.empty(), "Tag name cannot be empty");
+  auto it = updated_refs_.find(name);
+  ICEBERG_BUILDER_CHECK(it != updated_refs_.end(), "Tag does not exist: {}", name);
+  ICEBERG_BUILDER_CHECK(it->second->type() == SnapshotRefType::kTag,
+                        "Ref '{}' is a branch not a tag", name);
+  updated_refs_.erase(it);
+  return *this;
+}
+
+UpdateSnapshotReference& UpdateSnapshotReference::RenameBranch(
+    const std::string& name, const std::string& new_name) {
+  ICEBERG_BUILDER_CHECK(!name.empty(), "Branch to rename cannot be empty");
+  ICEBERG_BUILDER_CHECK(!new_name.empty(), "New branch name cannot be empty");
+  ICEBERG_BUILDER_CHECK(name != SnapshotRef::kMainBranch, "Cannot rename main branch");
+  auto it = updated_refs_.find(name);
+  ICEBERG_BUILDER_CHECK(it != updated_refs_.end(), "Branch does not exist: {}", name);
+  ICEBERG_BUILDER_CHECK(it->second->type() == SnapshotRefType::kBranch,
+                        "Ref '{}' is a tag not a branch", name);
+  auto [_, inserted] = updated_refs_.emplace(new_name, it->second);
+  ICEBERG_BUILDER_CHECK(inserted, "Ref '{}' already exists", new_name);
+  updated_refs_.erase(it);
+  return *this;
+}
+
+UpdateSnapshotReference& UpdateSnapshotReference::ReplaceBranch(const std::string& name,
+                                                                int64_t snapshot_id) {
+  ICEBERG_BUILDER_CHECK(!name.empty(), "Branch name cannot be empty");
+  auto it = updated_refs_.find(name);
+  ICEBERG_BUILDER_CHECK(it != updated_refs_.end(), "Branch does not exist: {}", name);
+  ICEBERG_BUILDER_CHECK(it->second->type() == SnapshotRefType::kBranch,
+                        "Ref '{}' is a tag not a branch", name);
+  it->second->snapshot_id = snapshot_id;
+  return *this;
+}
+
+UpdateSnapshotReference& UpdateSnapshotReference::ReplaceBranch(const std::string& from,
+                                                                const std::string& to) {
+  return ReplaceBranchInternal(from, to, false);
+}
+
+UpdateSnapshotReference& UpdateSnapshotReference::FastForward(const std::string& from,
+                                                              const std::string& to) {
+  return ReplaceBranchInternal(from, to, true);
+}
+
+UpdateSnapshotReference& UpdateSnapshotReference::ReplaceBranchInternal(
+    const std::string& from, const std::string& to, bool fast_forward) {
+  ICEBERG_BUILDER_CHECK(!from.empty(), "Branch to update cannot be empty");
+  ICEBERG_BUILDER_CHECK(!to.empty(), "Destination ref cannot be empty");
+  auto to_it = updated_refs_.find(to);
+  ICEBERG_BUILDER_CHECK(to_it != updated_refs_.end(), "Ref does not exist: {}", to);
+
+  auto from_it = updated_refs_.find(from);
+  if (from_it == updated_refs_.end()) {
+    return CreateBranch(from, to_it->second->snapshot_id);
+  }
+
+  ICEBERG_BUILDER_CHECK(from_it->second->type() == SnapshotRefType::kBranch,
+                        "Ref '{}' is a tag not a branch", from);
+
+  // Nothing to replace if snapshot IDs are the same
+  if (to_it->second->snapshot_id == from_it->second->snapshot_id) {
+    return *this;
+  }
+
+  if (fast_forward) {
+    const auto& base_metadata = transaction_->current();
+    ICEBERG_BUILDER_ASSIGN_OR_RETURN(
+        auto target_is_ancestor,
+        SnapshotUtil::IsAncestorOf(
+            from_it->second->snapshot_id, to_it->second->snapshot_id,
+            [&base_metadata](int64_t id) { return base_metadata.SnapshotById(id); }));
+
+    ICEBERG_BUILDER_CHECK(target_is_ancestor,
+                          "Cannot fast-forward: {} is not an ancestor of {}", from, to);
+  }
+
+  from_it->second->snapshot_id = to_it->second->snapshot_id;
+  return *this;
+}
+
+UpdateSnapshotReference& UpdateSnapshotReference::ReplaceTag(const std::string& name,
+                                                             int64_t snapshot_id) {
+  ICEBERG_BUILDER_CHECK(!name.empty(), "Tag name cannot be empty");
+  auto it = updated_refs_.find(name);
+  ICEBERG_BUILDER_CHECK(it != updated_refs_.end(), "Tag does not exist: {}", name);
+  ICEBERG_BUILDER_CHECK(it->second->type() == SnapshotRefType::kTag,
+                        "Ref '{}' is a branch not a tag", name);
+  it->second->snapshot_id = snapshot_id;
+  return *this;
+}
+
+UpdateSnapshotReference& UpdateSnapshotReference::SetMinSnapshotsToKeep(
+    const std::string& name, int32_t min_snapshots_to_keep) {
+  ICEBERG_BUILDER_CHECK(!name.empty(), "Branch name cannot be empty");
+  auto it = updated_refs_.find(name);
+  ICEBERG_BUILDER_CHECK(it != updated_refs_.end(), "Branch does not exist: {}", name);
+  ICEBERG_BUILDER_CHECK(it->second->type() == SnapshotRefType::kBranch,
+                        "Ref '{}' is a tag not a branch", name);
+  std::get<SnapshotRef::Branch>(it->second->retention).min_snapshots_to_keep =
+      min_snapshots_to_keep;
+  ICEBERG_BUILDER_CHECK(it->second->Validate(),
+                        "Invalid min_snapshots_to_keep {} for branch '{}'",
+                        min_snapshots_to_keep, name);
+  return *this;
+}
+
+UpdateSnapshotReference& UpdateSnapshotReference::SetMaxSnapshotAgeMs(
+    const std::string& name, int64_t max_snapshot_age_ms) {
+  ICEBERG_BUILDER_CHECK(!name.empty(), "Branch name cannot be empty");
+  auto it = updated_refs_.find(name);
+  ICEBERG_BUILDER_CHECK(it != updated_refs_.end(), "Branch does not exist: {}", name);
+  ICEBERG_BUILDER_CHECK(it->second->type() == SnapshotRefType::kBranch,
+                        "Ref '{}' is a tag not a branch", name);
+  std::get<SnapshotRef::Branch>(it->second->retention).max_snapshot_age_ms =
+      max_snapshot_age_ms;
+  ICEBERG_BUILDER_CHECK(it->second->Validate(),
+                        "Invalid max_snapshot_age_ms {} for branch '{}'",
+                        max_snapshot_age_ms, name);
+  return *this;
+}
+
+UpdateSnapshotReference& UpdateSnapshotReference::SetMaxRefAgeMs(const std::string& name,
+                                                                 int64_t max_ref_age_ms) {
+  ICEBERG_BUILDER_CHECK(!name.empty(), "Reference name cannot be empty");
+  auto it = updated_refs_.find(name);
+  ICEBERG_BUILDER_CHECK(it != updated_refs_.end(), "Ref does not exist: {}", name);
+  if (it->second->type() == SnapshotRefType::kBranch) {
+    std::get<SnapshotRef::Branch>(it->second->retention).max_ref_age_ms = max_ref_age_ms;
+  } else {
+    std::get<SnapshotRef::Tag>(it->second->retention).max_ref_age_ms = max_ref_age_ms;
+  }
+  ICEBERG_BUILDER_CHECK(it->second->Validate(), "Invalid max_ref_age_ms {} for ref '{}'",
+                        max_ref_age_ms, name);
+  return *this;
+}
+
+Result<std::unordered_map<std::string, std::shared_ptr<SnapshotRef>>>
+UpdateSnapshotReference::Apply() {
+  ICEBERG_RETURN_UNEXPECTED(CheckErrors());
+  return updated_refs_;
+}
+
+}  // namespace iceberg