def _from_catalog(self):
        if self.dbconn.version < 90100:
            self.query = QUERY_PRE91
        for col in self.fetch():
            sch, tbl = col.key()
            if (sch, tbl) not in self:
                self[(sch, tbl)] = []
            self[(sch, tbl)].append(col)
Initialize the dictionary of columns by querying the catalogs
dataset/ETHPy150Open perseas/Pyrseas/pyrseas/dbobject/column.py/ColumnDict._from_catalog