Thread: send Describe Portal message in PQsendPrepare

send Describe Portal message in PQsendPrepare

From
Manlio Perillo
Date:
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Hi.

What is the reason why PQsendPrepare function does not send a
Describe Portal message?

Just as a proof of concept, I wrote a very simple patch, attached, and
it *seems* to work.

Sending a Describe Portal message, make it possible for PQsendPrepare
function to *return* a PGresult with more useful informations, instead
of just the result status.



Thanks   Manlio Perillo
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Attachment

Re: send Describe Portal message in PQsendPrepare

From
Tom Lane
Date:
Manlio Perillo <manlio.perillo@gmail.com> writes:
> What is the reason why PQsendPrepare function does not send a
> Describe Portal message?

That would add a round trip, no?

> Sending a Describe Portal message, make it possible for PQsendPrepare
> function to *return* a PGresult with more useful informations, instead
> of just the result status.

That's *definitely* wrong, because the entire point of the PQsend
functions is they don't wait for a server response.
        regards, tom lane



Re: send Describe Portal message in PQsendPrepare

From
Manlio Perillo
Date:
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Il 11/02/2013 22:39, Tom Lane ha scritto:
> Manlio Perillo <manlio.perillo@gmail.com> writes:
>> What is the reason why PQsendPrepare function does not send a
>> Describe Portal message?
> 
> That would add a round trip, no?
> 

Well, no.

An extra round trip is required with current implementation, since I
need to call PQsendPrepare, wait for server response, call
PQsendDescribePrepared, wait for server response.

>> Sending a Describe Portal message, make it possible for PQsendPrepare
>> function to *return* a PGresult with more useful informations, instead
>> of just the result status.
> 
> That's *definitely* wrong, because the entire point of the PQsend
> functions is they don't wait for a server response.
> 

The PQsendQueryParams sends the following protocol messages:

* Parse
* Bind
* Describe Portal
* Execute
* Sync

and of course does not wait for each response, since this is done in the
state machine.

I noted that PQsendQueryParams sends a Describe Portal message, and I
found it strange that the same is not done by PQsendPrepare.

I wrote the patch to check if this was done due to some technical
reason, but this seems to not be the case.


>             regards, tom lane


Regards   Manlio Perillo
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