On Fri, Feb 21, 2014 at 4:56 PM, Ronan Dunklau <ronan.dunk...@dalibo.com>wrote:
> Le vendredi 21 février 2014 16:45:20 Atri Sharma a écrit : > > On Fri, Feb 21, 2014 at 4:39 PM, Ronan Dunklau > <ronan.dunk...@dalibo.com>wrote: > > > > I havent had a look at the patch yet since I dont have a nice editor > > > > > > right > > > > > > > now, but how do you handle inter operability between datatypes? > > > > Specifically, how do you handle those datatypes which have a > different > > > > > > name > > > > > > > from the PostgreSQL name for them and/or are stored in a different > > > > > > manner? > > > > > > Do you mean in general, or for the postgres_fdw specifically ? > > > > > > In general, only valid column types should be accepted in the > > > CreateForeignTableStmt. The CreateForeignTableStmt is passed through > > > DefineRelation, which takes care of looking up the actual data types. > > > > > > For the postgres_fdw POC implementation, this is done by parsing the > > > attributes type from the query result with the regtype input functions. > > > The > > > attribute typmod is injected too. > > > > I actually meant in general. Thanks for the reply. > > > > So please help me understand here. How exactly does > CreateForeignTableStmt > > help in type compatibility? > > I'm not sure I understand your concern. It doesn't help in type > compatibility, > it is still the responsibility of the FDW to convert local types to remote > ones. > Yeah, thats what I wondered. Ok, now I get it. The responsibility of FDW shall suffice for us. > > The CreateForeignTableStmt defines the column, with their types. It is > executed locally to create a new foreign table according to a remote > description of the table. The only difference with a user-written > CreateForeignTable statement is that the structure is crafted by the FDW > instead of the parser. > Got that. > > > A statement may be valid on a foreign server but may not be compatible. > > Do you mean the CreateForeignTableStmt ? It has to be valid locally, or it > won't be executed. It is the FDW responsibility to build this statement in > such a way that it is valid locally. > Yes, I understand it now. My concerns are not valid anymore. Thanks for the detailed description. Regards, Atri -- Regards, Atri *l'apprenant*
