Re: FDW oddity

On 04/11/2015 05:10 PM, Tom Lane wrote:
> Andrew Dunstan <andrew(at)dunslane(dot)net> writes:
>> I have just noticed something slightly odd. The traces (obtained by
>> setting client_min_messages to debug1) from the blackhole FDW show that
>> the handler function is called each time an INSERT is performed. This is
>> not the case for SELECT, UPDATE or DELETE. It looks at first glance like
>> a buglet. Can anyone suggest why this should be so?
> What do you mean by "the handler function", and for that matter what do
> you define as "each time"? The ExecForeignInsert method certainly ought
> to be called once per row inserted, but the same is true of
> ExecForeignUpdate and ExecForeignDelete. The setup methods such as
> BeginForeignModify should only be called once per query though.

I mean this function:

Datum
blackhole_fdw_handler(PG_FUNCTION_ARGS)
{
FdwRoutine *fdwroutine = makeNode(FdwRoutine);

elog(DEBUG1,"entering function %s",__func__);

/* assign the handlers for the FDW */

...
}

And it is called at the beginning of every INSERT statement, before
blackholePlanForeignModify() is called

cheers

andrew