Re: [PATCH 4/4] Add tests to dblink covering use of COPY TO FUNCTION

On Tue, Nov 24, 2009 at 9:35 PM, Pavel Stehule <pavel.stehule@gmail.com> wrote:
> 2009/11/25 Daniel Farina <drfarina@gmail.com>:
>> On Tue, Nov 24, 2009 at 8:45 PM, Pavel Stehule <pavel.stehule@gmail.com> wrote:
>>> It depends on design. I don't thing so internal is necessary. It is
>>> just wrong design.
>>
>> Depends on how lean you want to be when doing large COPY...right now
>> the cost is restricted to having to call a function pointer and a few
>> branches.  If you want to take SQL values, then the semantics of
>> function calling over a large number of rows is probably notably more
>> expensive, although I make no argument against the fact that the
>> non-INTERNAL version would give a lot more people more utility.
>
> I believe so using an "internal" minimalize necessary changes in COPY
> implementation. Using a funcapi needs more work inside COPY -  you
> have to take some functionality from COPY to stream functions.
> Probably the most slow operations is parsing - calling a input
> functions. This is called once every where. Second slow operation is
> reading from network - it is same. So I don't see too much reasons,
> why non internal implementation have to be significant slower than
> your actual implementation. I am sure, so it needs more work.

You are probably right.  We could try coercing to bytea and back out
to bytes, although it seems like a superfluous cost to force
*everyone* to pay just to get the same bytes to a network buffer.

fdr