DbProfilerBase.py 文件源码

def _query_column_profile(self, column_names, query):
        """Common code shared by PostgreSQL/MySQL/Oracle/MSSQL profilers
        to collect column profiles of the table.

        Args:
          column_names(list): column names.
          query(str): a query string to be executed on each database.

        Returns:
          tuple: (num_rows, minmax, nulls)
                 minmax and nulls are dictionaries having column names as
                 the keys.
        """
        _minmax = {}
        _nulls = {}
        num_rows = None
        try:
            rs = self.dbdriver.q2rs(query)
            assert len(rs.resultset) == 1

            a = copy.copy(list(rs.resultset[0]))
            num_rows = a.pop(0)
            log.trace("_query_column_profile: rows %d" % num_rows)
            i = 0
            while len(a) > 0:
                nulls = a.pop(0)
                colmin = a.pop(0)
                colmax = a.pop(0)
                log.trace(("_query_column_profile: col %s %d %s %s" %
                          (column_names[i], nulls, colmin, colmax)))
                _minmax[column_names[i]] = [colmin, colmax]
                _nulls[column_names[i]] = nulls
                i += 1
        except QueryError as e:
            log.error(_("Could not get row count/num of "
                        "nulls/min/max values."),
                      detail=e.value, query=query)
            raise e

        log.trace("_query_column_profile: %s" % str(_minmax))
        return (num_rows, _minmax, _nulls)