# Interface for the data source used in queries. # Currently only includes query capabilities. class Source: def __init__(self): None def isQueryable(self): return False # Check if the source will support the execution of an expression, # given that clauses have already been pushed into it. def supports(self,clauses,expr,visible_vars): return False # Database source for all relational database sources. Currently there is # no common functionality across different RDBMS sources class RDBMSTable(Source): def isQueryable(self): return True