[refactor](read-uncommitted) Move uncommitted rowset registration out of set_txn_related_delete_bitmap

Registration is not related to delete bitmaps and should run for all
table types, not just MoW. Extract to a separate register_uncommitted_rowset
method and call it as step 7 in cloud_tablets_channel close flow.

Also fixes a bug where MoW tablets with skip_writing_rowset_metadata
would return early and skip registration.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: dataroaring

be/src/cloud/cloud_delta_writer.cpp

@@ -146,4 +146,8 @@ Status CloudDeltaWriter::set_txn_related_delete_bitmap() {
     return rowset_builder()->set_txn_related_delete_bitmap();
 }
 
+void CloudDeltaWriter::register_uncommitted_rowset() {
+    rowset_builder()->register_uncommitted_rowset();
+}
+
 } // namespace doris

be/src/cloud/cloud_delta_writer.h

@@ -52,6 +52,9 @@ class CloudDeltaWriter final : public BaseDeltaWriter {
     Status commit_rowset();
 
     Status set_txn_related_delete_bitmap();
+
+    void register_uncommitted_rowset();
+
     std::shared_ptr<ResourceContext> resource_context() { return _resource_ctx; }
 
 private:

be/src/cloud/cloud_rowset_builder.cpp

@@ -159,22 +159,24 @@ Status CloudRowsetBuilder::set_txn_related_delete_bitmap() {
                 _req.txn_expiration, _partial_update_info);
     }
 
-    // Register uncommitted rowset for READ UNCOMMITTED visibility.
-    // For MoW tablets, capture the already-computed delete bitmap.
-    if (auto* registry = _engine.uncommitted_rowset_registry()) {
-        auto entry = std::make_shared<UncommittedRowsetEntry>();
-        entry->rowset = _rowset;
-        entry->transaction_id = _req.txn_id;
-        entry->partition_id = _req.partition_id;
-        entry->tablet_id = _tablet->tablet_id();
-        entry->unique_key_merge_on_write = _tablet->enable_unique_key_merge_on_write();
-        if (entry->unique_key_merge_on_write && _delete_bitmap) {
-            entry->committed_delete_bitmap = std::make_shared<DeleteBitmap>(*_delete_bitmap);
-        }
-        registry->register_rowset(std::move(entry));
-    }
-
     return Status::OK();
 }
+
+void CloudRowsetBuilder::register_uncommitted_rowset() {
+    auto* registry = _engine.uncommitted_rowset_registry();
+    if (!registry || !_rowset) {
+        return;
+    }
+    auto entry = std::make_shared<UncommittedRowsetEntry>();
+    entry->rowset = _rowset;
+    entry->transaction_id = _req.txn_id;
+    entry->partition_id = _req.partition_id;
+    entry->tablet_id = _tablet->tablet_id();
+    entry->unique_key_merge_on_write = _tablet->enable_unique_key_merge_on_write();
+    if (entry->unique_key_merge_on_write && _delete_bitmap) {
+        entry->committed_delete_bitmap = std::make_shared<DeleteBitmap>(*_delete_bitmap);
+    }
+    registry->register_rowset(std::move(entry));
+}
 #include "common/compile_check_end.h"
 } // namespace doris

be/src/cloud/cloud_rowset_builder.h

@@ -39,6 +39,9 @@ class CloudRowsetBuilder final : public BaseRowsetBuilder {
 
     Status set_txn_related_delete_bitmap();
 
+    // Register uncommitted rowset for READ UNCOMMITTED visibility.
+    void register_uncommitted_rowset();
+
     void set_skip_writing_rowset_metadata(bool skip) { _skip_writing_rowset_metadata = skip; }
 
 private:

be/src/cloud/cloud_tablets_channel.cpp

@@ -261,6 +261,11 @@ Status CloudTabletsChannel::close(LoadChannel* parent, const PTabletWriterAddBlo
         it++;
     }
 
+    // 7. Register uncommitted rowsets for READ UNCOMMITTED visibility
+    for (auto* writer : writers_to_commit) {
+        writer->register_uncommitted_rowset();
+    }
+
     tablet_vec->Reserve(static_cast<int>(writers_to_commit.size()));
     for (auto* writer : writers_to_commit) {
         PTabletInfo* tablet_info = tablet_vec->Add();