[GitHub] [iceberg] kbendick commented on a diff in pull request #4950: Core: Support metadata table loading in the REST catalog

[GitBox <gi...@apache.org>]

kbendick commented on code in PR #4950:
URL: https://github.com/apache/iceberg/pull/4950#discussion_r888498511


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core/src/main/java/org/apache/iceberg/rest/RESTSessionCatalog.java:
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@@ -209,12 +211,40 @@ private LoadTableResponse loadInternal(SessionContext context, TableIdentifier i
 
   @Override
   public Table loadTable(SessionContext context, TableIdentifier identifier) {
-    LoadTableResponse response = loadInternal(context, identifier);
+    MetadataTableType metadataType;
+    LoadTableResponse response;
+    try {
+      response = loadInternal(context, identifier);
+      metadataType = null;
+
+    } catch (NoSuchTableException original) {
+      metadataType = MetadataTableType.from(identifier.name());
+      if (metadataType != null) {
+        // attempt to load a metadata table using the identifier's namespace as the base table
+        TableIdentifier baseIdent = TableIdentifier.of(identifier.namespace().levels());
+        try {
+          response = loadInternal(context, baseIdent);
+        } catch (NoSuchTableException ignored) {
+          // the base table does not exist
+          throw original;
+        }
+      } else {
+        // name is not a metadata table
+        throw original;
+      }
+    }
+
     Pair<RESTClient, FileIO> clients = tableClients(response.config());
     AuthSession session = tableSession(response.config(), session(context));
     RESTTableOperations ops = new RESTTableOperations(
         clients.first(), paths.table(identifier), session::headers, clients.second(), response.tableMetadata());
-    return new BaseTable(ops, fullTableName(identifier));
+
+    BaseTable table = new BaseTable(ops, fullTableName(identifier));
+    if (metadataType != null) {
+      return MetadataTableUtils.createMetadataTableInstance(table, metadataType);
+    }
+
+    return table;

Review Comment:
   The `table` is being used inside of `createMetadataTableInstance(table, metadataType)` regardless.
   
   But I do somewhat agree with your style point, that it might be more readable to duplicate the line of code.



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