following is a little fix for libpq.

    PQexec  handles  the possibility of multiple results from one
    query by simply submitting an empty  query  after  the  first
    result and waiting for an 'I' message.

    Rules  can  generate  errors with transaction abort after the
    first 'C' message was recieved (e.g. if a C-language function
    used  in  a rule calls elog(WARN, ...)). Thus we have to look
    for.

Jan(wieck@sapserv.debis.de)

src/interfaces/libpq/fe-exec.c

@@ -7,7 +7,7 @@
  *
  *
  * IDENTIFICATION
- *    $Header: /cvsroot/pgsql/src/interfaces/libpq/fe-exec.c,v 1.18 1996/09/16 05:50:46 scrappy Exp $
+ *    $Header: /cvsroot/pgsql/src/interfaces/libpq/fe-exec.c,v 1.19 1996/11/20 22:35:19 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -363,7 +363,7 @@ PGresult*
 PQexec(PGconn* conn, const char* query)
 {
   PGresult *result;
-  int id, clear;
+  int id, clear, error;
   char buffer[MAX_MESSAGE_LEN];
   char cmdStatus[MAX_MESSAGE_LEN];
   char pname[MAX_MESSAGE_LEN]; /* portal name */
@@ -459,6 +459,7 @@ PQexec(PGconn* conn, const char* query)
 	// until an 'I' is received.
 	*/
 	clear = 0;
+	error = 0;
 
 	pqPuts("Q ",pfout,pfdebug); /* send an empty query */
 #ifdef PQ_NOTIFY_PATCH
@@ -472,8 +473,19 @@ PQexec(PGconn* conn, const char* query)
 	  {
 	    if (pqGets(buffer,ERROR_MSG_LENGTH,pfin,pfdebug) == 1)
 	      clear = 1;
+	    /*
+	    // Rules can create error messages while we are waiting
+	    // for the 'I'.
+	    */
+	    if (buffer[0] == 'E') {
+	        strcpy(conn->errorMessage, &buffer[1]);
+		error++;
+	    }
 	    clear = (buffer[0] == 'I');
 	  }
+	if (error) {
+	    return (PGresult*)NULL;
+	}
 	result = makeEmptyPGresult(conn,PGRES_COMMAND_OK);
 	strncpy(result->cmdStatus,cmdStatus, CMDSTATUS_LEN-1);
 	return result;