Re: SQL/MED estimated time of arrival?

On Thu, Nov 4, 2010 at 6:04 PM, Shigeru HANADA
<hanada(at)metrosystems(dot)co(dot)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