Apply suggestions

Author: KodaiD

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

@@ -706,7 +706,7 @@ public enum CoreError implements ScalarDbError {
       "Cassandra does not support renaming non-primary key columns",
       "",
       ""),
-  DB2_RENAME_PRIMARY_OR_INDEX_KEY_COLUMN_NOT_SUPPORTED(
+  JDBC_DB2_RENAME_PRIMARY_OR_INDEX_KEY_COLUMN_NOT_SUPPORTED(
       Category.USER_ERROR,
       "0222",
       "Db2 does not support renaming primary key or index key columns",

core/src/main/java/com/scalar/db/storage/jdbc/JdbcAdmin.java

@@ -890,28 +890,17 @@ public void renameColumn(
       throws ExecutionException {
     try {
       TableMetadata currentTableMetadata = getTableMetadata(namespace, table);
+      rdbEngine.throwIfRenameColumnNotSupported(oldColumnName, currentTableMetadata);
       assert currentTableMetadata != null;
       TableMetadata.Builder tableMetadataBuilder =
           TableMetadata.newBuilder(currentTableMetadata).renameColumn(oldColumnName, newColumnName);
       if (currentTableMetadata.getPartitionKeyNames().contains(oldColumnName)) {
-        if (rdbEngine instanceof RdbEngineDb2) {
-          throw new UnsupportedOperationException(
-              CoreError.DB2_RENAME_PRIMARY_OR_INDEX_KEY_COLUMN_NOT_SUPPORTED.buildMessage());
-        }
         tableMetadataBuilder.renamePartitionKey(oldColumnName, newColumnName);
       }
       if (currentTableMetadata.getClusteringKeyNames().contains(oldColumnName)) {
-        if (rdbEngine instanceof RdbEngineDb2) {
-          throw new UnsupportedOperationException(
-              CoreError.DB2_RENAME_PRIMARY_OR_INDEX_KEY_COLUMN_NOT_SUPPORTED.buildMessage());
-        }
         tableMetadataBuilder.renameClusteringKey(oldColumnName, newColumnName);
       }
       if (currentTableMetadata.getSecondaryIndexNames().contains(oldColumnName)) {
-        if (rdbEngine instanceof RdbEngineDb2) {
-          throw new UnsupportedOperationException(
-              CoreError.DB2_RENAME_PRIMARY_OR_INDEX_KEY_COLUMN_NOT_SUPPORTED.buildMessage());
-        }
         tableMetadataBuilder.renameSecondaryIndex(oldColumnName, newColumnName);
       }
       TableMetadata updatedTableMetadata = tableMetadataBuilder.build();

core/src/main/java/com/scalar/db/storage/jdbc/RdbEngineDb2.java

@@ -527,6 +527,16 @@ public String getProjectionsSqlForSelectQuery(
         .collect(Collectors.joining(","));
   }
 
+  @Override
+  public void throwIfRenameColumnNotSupported(String columnName, TableMetadata tableMetadata) {
+    if (tableMetadata.getPartitionKeyNames().contains(columnName)
+        || tableMetadata.getClusteringKeyNames().contains(columnName)
+        || tableMetadata.getSecondaryIndexNames().contains(columnName)) {
+      throw new UnsupportedOperationException(
+          CoreError.JDBC_DB2_RENAME_PRIMARY_OR_INDEX_KEY_COLUMN_NOT_SUPPORTED.buildMessage());
+    }
+  }
+
   private String getProjection(String columnName, DataType dataType) {
     if (dataType == DataType.DATE) {
       // Selecting a DATE column requires special handling. We need to cast the DATE column values

core/src/main/java/com/scalar/db/storage/jdbc/RdbEngineStrategy.java

@@ -272,6 +272,15 @@ default void throwIfDuplicatedIndexWarning(SQLWarning warning) throws SQLExcepti
     // Do nothing
   }
 
+  /**
+   * Throws an exception if renaming columns is not supported in the underlying database.
+   *
+   * @param columnName the current name of the column to rename
+   * @param tableMetadata the current table metadata
+   * @throws UnsupportedOperationException if renaming the column is not supported
+   */
+  default void throwIfRenameColumnNotSupported(String columnName, TableMetadata tableMetadata) {}
+
   default void setConnectionToReadOnly(Connection connection, boolean readOnly)
       throws SQLException {
     connection.setReadOnly(readOnly);