On Thu, Nov 4, 2010 at 6:04 PM, Shigeru HANADA <han...@metrosystems.co.jp> wrote: > For example: > * PRIMARY ACCESS_METHOD -> HANDLER of FOREIGN DATA WRAPPER > * am_scancost() -> FdwRoutine.EstimateCosts() > * am_open() -> FdwRoutine.Open() > * am_beginscan() -> first call of FdwRoutine.Iterate()?
It might be good to have a separated "beginscan" method if we use asynchronous scans in multiple foreign servers in one query because multiple foreign servers can run their queries in parallel. (Imagine that pushing-down aggregate function into each foreign server.) I think it is different from "open" because it is called before query execution, for example by EXPLAIN. > * am_getnext() -> FdwRoutine.Iterate() > * am_rescan() -> FdwRoutine.ReOpen() > * am_close() -> FdwRoutine.Close() > * Table descriptor -> Relation, Form_pg_class > * Qual descriptor -> PlanState.qual Do you think you have all counterpart methods for VTI AMs? If so, it's a good news ;-) We could support foreign table features as same level as Informix. -- Itagaki Takahiro -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
