Message-ID: <3E79E21E.6020400@ghaering.de>
Date: Thu, 20 Mar 2003 16:45:34 +0100
User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.0; en-US;
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To: Bruce Momjian <pgman@candle.pha.pa.us>
Cc: pgsql-interfaces@postgresql.org
Subject: Re: I want to send comments to the backend!
References: <200303201522.h2KFMpp24991@candle.pha.pa.us>
In-Reply-To: <200303201522.h2KFMpp24991@candle.pha.pa.us>
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From: =?ISO-8859-1?Q?Gerhard_H=E4ring?=
	<lists+dated+1048607365.9fec41@ghaering.de>

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Bruce Momjian wrote:
> Gerhard Häring wrote:
> 
>>Why can't I send comments like
>>
>>    -- a comment
>>
>>to the backend using libpq? Are these only handled in psql? Please allow to
>>send comments to the backend, as I really need them.
> 
> The backend should handle them fine.  Can you give us pgsql version and
> an example.

I experience it on 7.2.1 on Debian Woody here. Same on 7.3.1 AFAIK.

I attached a minimal libpq example in C (to rule out any interference 
from my Python modules) that shows the problem.

-- Gerhard


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/*
 * testlibpq.c
 *
 * Test the C version of libpq, the PostgreSQL frontend
 * library.
 */
#include <stdio.h>
#include <libpq-fe.h>

void
exit_nicely(PGconn *conn)
{
    PQfinish(conn);
    exit(1);
}

main()
{
    char       *pghost,
               *pgport,
               *pgoptions,
               *pgtty;
    char       *dbName;
    int         nFields;
    int         i,
                j;

    /* FILE *debug; */

    PGconn     *conn;
    PGresult   *res;

    /*
     * begin, by setting the parameters for a backend connection if the
     * parameters are null, then the system will try to use reasonable
     * defaults by looking up environment variables or, failing that,
     * using hardwired constants
     */
    pghost = NULL;              /* host name of the backend server */
    pgport = NULL;              /* port of the backend server */
    pgoptions = NULL;           /* special options to start up the backend
                                 * server */
    pgtty = NULL;               /* debugging tty for the backend server */
    dbName = "template1";

    /* make a connection to the database */
    conn = PQsetdb(pghost, pgport, pgoptions, pgtty, dbName);

    /*
     * check to see that the backend connection was successfully made
     */
    if (PQstatus(conn) == CONNECTION_BAD)
    {
        fprintf(stderr, "Connection to database '%s' failed.\n", dbName);
        fprintf(stderr, "%s", PQerrorMessage(conn));
        exit_nicely(conn);
    }

    /* debug = fopen("/tmp/trace.out","w"); */
    /* PQtrace(conn, debug);  */

    /* start a transaction block */
    res = PQexec(conn, "-- foobar");
    if (!res || PQresultStatus(res) != PGRES_COMMAND_OK)
    {
        fprintf(stderr, "couldn't process comment\n");
        PQclear(res);
        exit_nicely(conn);
    }

    /*
     * should PQclear PGresult whenever it is no longer needed to avoid
     * memory leaks
     */
    PQclear(res);

    /* close the connection to the database and cleanup */
    PQfinish(conn);

    /* fclose(debug); */
    return 0;
}

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