fix(inspect): address metadata table review feedback

Author: WZhuo

src/iceberg/inspect/metadata_table.cc

@@ -35,20 +35,10 @@ MetadataTable::MetadataTable(std::shared_ptr<Table> source_table,
 
 MetadataTable::~MetadataTable() = default;
 
-bool MetadataTable::supports_time_travel() const noexcept {
-  // Time travel is supported for tables that read from a single snapshot's
-  // manifests. Tables that scan all snapshots or return in-memory history do
-  // not.
-  switch (kind()) {
-    case Kind::kSnapshots:
-    case Kind::kHistory:
-      return false;
-  }
-  return false;
-}
+bool MetadataTable::supports_time_travel() const noexcept { return false; }
 
 Result<ArrowArray> MetadataTable::Scan(
-    std::optional<SnapshotSelection> /*snapshot_selection*/) {
+    const std::optional<SnapshotSelection>& /*snapshot_selection*/) {
   return NotSupported("Scan is not supported for this metadata table type");
 }
 

src/iceberg/inspect/metadata_table.h

@@ -62,10 +62,8 @@ class ICEBERG_EXPORT MetadataTable {
 
   /// \brief Whether this metadata table supports time-travel queries.
   ///
-  /// Time travel is supported for tables that read from a single snapshot's
-  /// manifests (e.g., Entries, Files, Manifests, Partitions). Tables that
-  /// scan all snapshots (All*) or return in-memory history (Snapshots,
-  /// History, Refs) do not support time travel.
+  /// The currently supported snapshots and history metadata tables do not
+  /// support time travel.
   bool supports_time_travel() const noexcept;
 
   /// \brief Scan the metadata table using the current snapshot.
@@ -80,7 +78,8 @@ class ICEBERG_EXPORT MetadataTable {
   ///
   /// The default implementation returns NotSupported. Subclasses override this
   /// to materialize their data.
-  virtual Result<ArrowArray> Scan(std::optional<SnapshotSelection> snapshot_selection);
+  virtual Result<ArrowArray> Scan(
+      const std::optional<SnapshotSelection>& snapshot_selection);
 
   const TableIdentifier& name() const { return identifier_; }
 

src/iceberg/inspect/snapshots_table.cc

@@ -69,7 +69,7 @@ Result<std::unique_ptr<SnapshotsTable>> SnapshotsTable::Make(
 }
 
 Result<ArrowArray> SnapshotsTable::Scan(
-    std::optional<SnapshotSelection> /*snapshot_selection*/) {
+    const std::optional<SnapshotSelection>& /*snapshot_selection*/) {
   ICEBERG_ASSIGN_OR_RAISE(auto builder, ArrowRowBuilder::Make(*schema()));
 
   for (const auto& snapshot : source_table()->snapshots()) {

src/iceberg/inspect/snapshots_table.h

@@ -45,7 +45,7 @@ class ICEBERG_EXPORT SnapshotsTable : public MetadataTable {
   /// The snapshots table always returns every known snapshot, so the
   /// snapshot_selection parameter is ignored.
   Result<ArrowArray> Scan(
-      std::optional<SnapshotSelection> /*snapshot_selection*/) override;
+      const std::optional<SnapshotSelection>& /*snapshot_selection*/) override;
 
  private:
   explicit SnapshotsTable(std::shared_ptr<Table> table);

src/iceberg/test/metadata_table_test_base.h

@@ -78,7 +78,7 @@ class MetadataTableTestBase : public ::testing::Test {
   /// \brief Import a Scan()-produced ArrowArray into an Arrow RecordBatch.
   static std::shared_ptr<::arrow::RecordBatch> FinishAndImport(ArrowArray array,
                                                                const Schema& schema) {
-    ArrowSchema c_schema;
+    ArrowSchema c_schema{};
     EXPECT_THAT(ToArrowSchema(schema, &c_schema), IsOk());
     auto arrow_schema = ::arrow::ImportSchema(&c_schema).ValueOrDie();