docs: protected List<String> getPrimaryKeys(String tableName) {
          List<String> pkCols = new ArrayList<String>();
          try {
              // Lower-case table names are required for PostgreSQL; we might need to
              // alter this if we use another comparison database (besides HSQL) someday
              ResultSet rs = dbconn.getMetaData().getPrimaryKeys(null, null, tableName.toLowerCase());
              while (rs.next()) {
                  pkCols.add(rs.getString(4));
              }
          } catch (SQLException e) {
              printCaughtException("In NonVoltDBBackend.getPrimaryKeys, caught SQLException: " + e);
          }
          return pkCols;
      }