Make drop column unsupported in CosmosAdmin and DynamoAdmin

Author: KodaiD

core/src/main/java/com/scalar/db/common/CoreError.java

@@ -684,6 +684,12 @@ public enum CoreError implements ScalarDbError {
       "The column %s is specified as a primary key or an index key",
       "",
       ""),
+  COSMOS_DROP_COLUMN_NOT_SUPPORTED(
+      Category.USER_ERROR,
+      "0217",
+      "Drop column functionality is not supported in Cosmos DB",
+      "",
+      ""),
 
   //
   // Errors for the concurrency error category

core/src/main/java/com/scalar/db/storage/cosmos/CosmosAdmin.java

@@ -647,18 +647,8 @@ columnName, getFullTableName(namespace, table)),
   @Override
   public void dropColumnFromTable(String namespace, String table, String columnName)
       throws ExecutionException {
-    try {
-      TableMetadata currentTableMetadata = getTableMetadata(namespace, table);
-      TableMetadata updatedTableMetadata =
-          TableMetadata.newBuilder(currentTableMetadata).removeColumn(columnName).build();
-      upsertTableMetadata(namespace, table, updatedTableMetadata);
-    } catch (ExecutionException e) {
-      throw new ExecutionException(
-          String.format(
-              "Adding the new %s column to the %s container failed",
-              columnName, getFullTableName(namespace, table)),
-          e);
-    }
+    throw new UnsupportedOperationException(
+        CoreError.COSMOS_DROP_COLUMN_NOT_SUPPORTED.buildMessage());
   }
 
   @Override

core/src/main/java/com/scalar/db/storage/dynamo/DynamoAdmin.java

@@ -1443,20 +1443,8 @@ columnName, getFullTableName(namespace, table)),
   @Override
   public void dropColumnFromTable(String nonPrefixedNamespace, String table, String columnName)
       throws ExecutionException {
-    Namespace namespace = Namespace.of(namespacePrefix, nonPrefixedNamespace);
-    try {
-      TableMetadata currentTableMetadata = getTableMetadata(nonPrefixedNamespace, table);
-      TableMetadata updatedTableMetadata =
-          TableMetadata.newBuilder(currentTableMetadata).removeColumn(columnName).build();
-
-      upsertTableMetadata(namespace, table, updatedTableMetadata);
-    } catch (ExecutionException e) {
-      throw new ExecutionException(
-          String.format(
-              "Dropping the %s column from the %s table failed",
-              columnName, getFullTableName(namespace, table)),
-          e);
-    }
+    throw new UnsupportedOperationException(
+        "Drop column functionality is not supported in DynamoDB");
   }
 
   @Override