feat: add MergingSnapshotUpdate

.github/workflows/sanitizer_test.yml

@@ -58,14 +58,18 @@ jobs:
       - name: Run Tests
         working-directory: build
         env:
-          ASAN_OPTIONS: log_path=out.log:detect_leaks=1:symbolize=1:strict_string_checks=1:halt_on_error=1:detect_container_overflow=0
+          ASAN_OPTIONS: log_path=${{ github.workspace }}/asan.log:detect_leaks=1:symbolize=1:strict_string_checks=1:halt_on_error=1:detect_container_overflow=0
           LSAN_OPTIONS: suppressions=${{ github.workspace }}/.github/lsan-suppressions.txt
-          UBSAN_OPTIONS: log_path=out.log:halt_on_error=1:print_stacktrace=1:suppressions=${{ github.workspace }}/.github/ubsan-suppressions.txt
+          UBSAN_OPTIONS: log_path=${{ github.workspace }}/ubsan.log:halt_on_error=1:print_stacktrace=1:suppressions=${{ github.workspace }}/.github/ubsan-suppressions.txt
         run: |
           ctest --output-on-failure
       - name: Save the test output
         if: always()
         uses: actions/upload-artifact@043fb46d1a93c77aae656e7c1c64a875d1fc6a0a # v7.0.1
         with:
           name: test-output
-          path: build/test/out.log*
+          path: |
+            asan.log*
+            ubsan.log*
+            build/Testing/Temporary/LastTest.log
+            build/Testing/Temporary/LastTestsFailed.log

src/iceberg/CMakeLists.txt

@@ -89,6 +89,7 @@ set(ICEBERG_SOURCES
     type.cc
     update/expire_snapshots.cc
     update/fast_append.cc
+    update/merging_snapshot_update.cc
     update/pending_update.cc
     update/set_snapshot.cc
     update/snapshot_manager.cc

src/iceberg/manifest/manifest_entry.h

@@ -374,7 +374,7 @@ struct ICEBERG_EXPORT ManifestEntry {
   ManifestEntry AsAdded() const {
     ManifestEntry copy = *this;
     copy.status = ManifestStatus::kAdded;
-    if (copy.data_file->first_row_id.has_value()) {
+    if (copy.data_file != nullptr && copy.data_file->first_row_id.has_value()) {
       copy.data_file = std::make_unique<DataFile>(*copy.data_file);
       copy.data_file->first_row_id = std::nullopt;
     }