On the pro*C program, Why is the CLOSE CURSOR not performed in the child-process?

Question

In summary...

int main() {       
                   
    pid_t childPid;
        
    EXEC SQL CONNECT :username IDENTIFIED BY :password;     
    for (;;)
    {
        childPid = fork();
        
        if(childPid > 0)
        {   // parent process
            ...
            ...
            ...                        
        }
        else if(childPid == 0)
        {  // chiled process
            EXEC SQL DECLARE c1 CURSOR FOR
             SELECT empno, ename, sal FROM emp;
     
            for (;;)
            {
               EXEC SQL OPEN c1;
               EXEC SQL FETCH c1 INTO :emp_rec;
      
               if(sqlca.sqlcode == 1403)
               {
                   EXEC SQL CLOSE c1;
                   EXEC SQL COMMIT WORK RELEASE;
                   break;
               }
               ...
               ...
               //A function that sends results to the Client program.
               SendPacketTOClient(fd,size);
            }
            EXEC SQL COMMIT WORK;
            exit(0);
        }
        else {  // fork Fail
            perror("fork Fail! \n");
            return -1;
        }
        
        sleep(60);            
    }
    retun 0;
}

As above, DB CONNECT is performed in the parent process and forks is performed every minute, and the child process ends with exit (0) after inquiry (DECLARE->OPEN->FETCH->CLOSE). There was no problem because it was processed until FETCH. But if CLOSE is not working properly, there was an ORA-01000: maximum open response error later. When I actually checked, the child process was created and it didn't close when it was terminated after finishing work.

After Serch, I found out that it was a problem because the Servie Process was one, so I solved it by branching the parent process and the child process DB connection.

I solved it, but I want to know the principle, so I leave a question. May I know why DECLARE, OPEN, and FETCH are executed, but COLSE is not executed?

Thanks.

Answer 1

Add "EXEC SQL FREE :c1;" Statement. This will free the open cursors. Also add "EXEC SQL ALLOCATE :c1;" Statement after declaring the cursor.