code: private function setConstraints()
      {
          $q = new QueryBuilder("SELECT ccu.column_name, tc.constraint_type FROM INFORMATION_SCHEMA.constraint_column_usage ccu JOIN information_schema.table_constraints tc ON ccu.constraint_name = tc.constraint_name WHERE tc.table_name = ccu.table_name AND ccu.table_name = $1", $this->tableName);
          $qResult = $q->execute();
          while ($qRow = pg_fetch_assoc($qResult)) {
              switch($qRow['constraint_type']) {
                  case 'PRIMARY KEY':
                      $this->primaryKeyColumnName = $qRow['column_name'];
                      break;
                  case 'UNIQUE':
                      $this->uniqueColumnNames[] = $qRow['column_name'];
              }
          }
      }
docs: note this will set uniqueColumnNames whether they are set as a constraint or an index