Re: [HACKERS] libpq and SPI - Mailing list pgsql-hackers

From Tom Lane
Subject Re: [HACKERS] libpq and SPI
Date
Msg-id 29785.921435659@sss.pgh.pa.us
Whole thread Raw
In response to Re: [HACKERS] libpq and SPI  (Clark Evans <clark.evans@manhattanproject.com>)
Responses RE: [HACKERS] libpq and SPI
Re: [HACKERS] libpq and SPI
Re: [HACKERS] libpq and SPI
List pgsql-hackers
> What is the problem? I'll research a SPI patch.

Check the hackers thread (last month I think) titled "libpq and SPI";
the problem occurs when one submits a utility statement rather than
a plannable query via SPI.  Apparently what is happening is that the
backend emits a 'T' message before it invokes the called statement
and then emits a 'D' message afterwards --- so if the called statement
causes a 'C' message to come out, libpq gets unhappy.  This seems
to be clearly a violation of the FE/BE protocol to me, so I don't think
it's libpq's fault.

Reasonable fixes might be to postpone the sending of 'T' till after
the invoked statement is executed, or to modify the traffic cop so
that a utility statement invoked from SPI doesn't send 'C'.

I know a little bit about the parts of the backend that communicate with
the frontend, but nothing about SPI, so I'm not well prepared to solve
the problem by myself.
        regards, tom lane


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