fix: use deregisterTable for dropTable and dropTable for purgeTable

lance-spark-base_2.12/src/main/java/org/lance/spark/BaseLanceNamespaceSparkCatalog.java

@@ -17,6 +17,7 @@
 import org.lance.WriteParams;
 import org.lance.namespace.LanceNamespace;
 import org.lance.namespace.errors.TableNotFoundException;
+import org.lance.namespace.model.DeregisterTableRequest;
 import org.lance.namespace.model.DescribeTableRequest;
 import org.lance.namespace.model.DescribeTableResponse;
 import org.lance.namespace.model.DropNamespaceRequest;
@@ -479,6 +480,23 @@ public Table alterTable(Identifier ident, TableChange... changes) throws NoSuchT
 
   @Override
   public boolean dropTable(Identifier ident) {
+    try {
+      Identifier tableId = transformIdentifierForApi(ident);
+      DeregisterTableRequest deregisterRequest = new DeregisterTableRequest();
+      for (String part : tableId.namespace()) {
+        deregisterRequest.addIdItem(part);
+      }
+      deregisterRequest.addIdItem(tableId.name());
+      namespace.deregisterTable(deregisterRequest);
+
+      return true;
+    } catch (Exception e) {
+      return false;
+    }
+  }
+
+  @Override
+  public boolean purgeTable(Identifier ident) {
     try {
       Identifier tableId = transformIdentifierForApi(ident);
       DropTableRequest dropRequest = new DropTableRequest();

lance-spark-base_2.12/src/test/java/org/lance/spark/BaseTestSparkDirectoryNamespace.java

@@ -13,6 +13,9 @@
  */
 package org.lance.spark;
 
+import org.junit.jupiter.api.BeforeEach;
+
+import java.io.IOException;
 import java.util.HashMap;
 import java.util.Map;
 
@@ -28,6 +31,18 @@ protected String getNsImpl() {
   protected Map<String, String> getAdditionalNsConfigs() {
     Map<String, String> configs = new HashMap<>();
     configs.put("root", tempDir.toString());
+    // Disable extra_level so "default" is treated as an actual child namespace
+    // This ensures manifest mode is used instead of directory listing mode
+    configs.put("extra_level", "");
     return configs;
   }
+
+  @BeforeEach
+  @Override
+  void setup() throws IOException {
+    super.setup();
+    // Create the "default" namespace explicitly so that DirectoryNamespace uses manifest mode
+    // instead of directory listing mode. This is required for deregisterTable to work correctly.
+    spark.sql("CREATE NAMESPACE " + catalogName + ".default");
+  }
 }