Unsupported versions: 7.0
This documentation is for an unsupported version of PostgreSQL.
You may want to view the same page for the current version, or one of the other supported versions listed above instead.

libpq Control Functions

  • PQsetNoticeProcessor Control reporting of notice and warning messages generated by libpq.

    typedef void (*PQnoticeProcessor) (void *arg, const char *message);
    PQsetNoticeProcessor(PGconn *conn,
                         PQnoticeProcessor proc,
                         void *arg);

By default, libpq prints "notice" messages from the backend on stderr, as well as a few error messages that it generates by itself. This behavior can be overridden by supplying a callback function that does something else with the messages. The callback function is passed the text of the error message (which includes a trailing newline), plus a void pointer that is the same one passed to PQsetNoticeProcessor. (This pointer can be used to access application-specific state if needed.) The default notice processor is simply

static void
defaultNoticeProcessor(void * arg, const char * message)
    fprintf(stderr, "%s", message);
To use a special notice processor, call PQsetNoticeProcessor just after creation of a new PGconn object.

The return value is the pointer to the previous notice processor. If you supply a callback function pointer of NULL, no action is taken, but the current pointer is returned.

Once you have set a notice processor, you should expect that that function could be called as long as either the PGconn object or PGresult objects made from it exist. At creation of a PGresult, the PGconn's current notice processor pointer is copied into the PGresult for possible use by routines like PQgetvalue.