Re: Bug #701: pqReadData() -- backend closed the channel

On Sat, 29 Jun 2002 pgsql-bugs@postgresql.org wrote:

> Short Description
> pqReadData() -- backend closed the channel unexpectedly.
>
> Long Description
> i have to fire a trigger whenever insertion is done on a table users
> that calls the postgres function which inturn calls a c function .
> wheever i am doing the insertion in the table it gives the followng error & terminates the backend:
>
> pqReadData() -- backend closed the channel unexpectedly.
>         This probably means the backend terminated abnormally
>         before or while processing the request.
> The connection to the server was lost. Attempting reset: Failed.
>
> i cannot find the solution to this problem .please help.
>
> Sample Code
> the c file that contains function is as follows:
>
> #include <stdio.h>
> #include "pgsql/postgres.h"
> void users();
>
> int main()
> {
> users();
> }
>
> void users()
> {
>         FILE *fp;
>         fp = fopen("/home/suresh/trigger/test.txt","w");
>         fputs("Hello this is c function",fp);
> }

I don't believe this is a valid trigger function. Looking at
the trigger documentation's simple example, I think the
function should return Datum and take PG_FUNCTION_ARGS (or
technically what that expands to, but...). I also think you
need a PG_FUNCTION_INFO_V1(users); and the function should
return the new row since you're using it as a before trigger.