diff --git a/src/interfaces/libpq/fe-connect.c b/src/interfaces/libpq/fe-connect.c
index aa1c0ced8b..79644b3413 100644
--- a/src/interfaces/libpq/fe-connect.c
+++ b/src/interfaces/libpq/fe-connect.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/interfaces/libpq/fe-connect.c,v 1.380 2009/11/29 20:14:53 petere Exp $
+ *	  $PostgreSQL: pgsql/src/interfaces/libpq/fe-connect.c,v 1.381 2009/12/02 04:38:35 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -83,8 +83,18 @@ static int ldapServiceLookup(const char *purl, PQconninfoOption *options,
 #define PGPASSFILE "pgpass.conf"
 #endif
 
-/* fall back options if they are not specified by arguments or defined
-   by environment variables */
+/*
+ * Pre-8.5 servers will return this SQLSTATE if asked to set
+ * application_name in a startup packet.  We hard-wire the value rather
+ * than looking into errcodes.h since it reflects historical behavior
+ * rather than that of the current code.
+ */
+#define ERRCODE_APPNAME_UNKNOWN "42704"
+
+/*
+ * fall back options if they are not specified by arguments or defined
+ * by environment variables
+ */
 #define DefaultHost		"localhost"
 #define DefaultTty		""
 #define DefaultOption	""
@@ -262,7 +272,6 @@ static int parseServiceInfo(PQconninfoOption *options,
 static char *pwdfMatchesString(char *buf, char *token);
 static char *PasswordFromFile(char *hostname, char *port, char *dbname,
 				 char *username);
-static PostgresPollingStatusType pqAppnamePoll(PGconn *conn);
 static void default_threadlock(int acquire);
 
 
@@ -901,6 +910,7 @@ connectDBStart(PGconn *conn)
 	conn->addr_cur = addrs;
 	conn->addrlist_family = hint.ai_family;
 	conn->pversion = PG_PROTOCOL(3, 0);
+	conn->send_appname = true;
 	conn->status = CONNECTION_NEEDED;
 
 	/*
@@ -1075,7 +1085,7 @@ PQconnectPoll(PGconn *conn)
 		case CONNECTION_MADE:
 			break;
 
-			/* pqSetenvPoll/pqAppnamePoll will decide whether to proceed. */
+			/* We allow pqSetenvPoll to decide whether to proceed. */
 		case CONNECTION_SETENV:
 			break;
 
@@ -1880,6 +1890,35 @@ keep_going:						/* We will come back to here until there is
 					if (res->resultStatus != PGRES_FATAL_ERROR)
 						appendPQExpBuffer(&conn->errorMessage,
 										  libpq_gettext("unexpected message from server during startup\n"));
+					else if (conn->send_appname &&
+							 (conn->appname || conn->fbappname))
+					{
+						/*
+						 * If we tried to send application_name, check to see
+						 * if the error is about that --- pre-8.5 servers will
+						 * reject it at this stage of the process.  If so,
+						 * close the connection and retry without sending
+						 * application_name.  We could possibly get a false
+						 * SQLSTATE match here and retry uselessly, but there
+						 * seems no great harm in that; we'll just get the
+						 * same error again if it's unrelated.
+						 */
+						const char *sqlstate;
+
+						sqlstate = PQresultErrorField(res, PG_DIAG_SQLSTATE);
+						if (sqlstate &&
+							strcmp(sqlstate, ERRCODE_APPNAME_UNKNOWN) == 0)
+						{
+							PQclear(res);
+							conn->send_appname = false;
+							/* Must drop the old connection */
+							pqsecure_close(conn);
+							closesocket(conn->sock);
+							conn->sock = -1;
+							conn->status = CONNECTION_NEEDED;
+							goto keep_going;
+						}
+					}
 
 					/*
 					 * if the resultStatus is FATAL, then conn->errorMessage
@@ -1899,12 +1938,6 @@ keep_going:						/* We will come back to here until there is
 				conn->addrlist = NULL;
 				conn->addr_cur = NULL;
 
-				/*
-				 * Note: To avoid changing the set of application-visible
-				 * connection states, v2 environment setup and v3 application
-				 * name setup both happen in the CONNECTION_SETENV state.
-				 */
-
 				/* Fire up post-connection housekeeping if needed */
 				if (PG_PROTOCOL_MAJOR(conn->pversion) < 3)
 				{
@@ -1913,13 +1946,6 @@ keep_going:						/* We will come back to here until there is
 					conn->next_eo = EnvironmentOptions;
 					return PGRES_POLLING_WRITING;
 				}
-				else if (conn->sversion >= 80500 &&
-						 (conn->appname || conn->fbappname))
-				{
-					conn->status = CONNECTION_SETENV;
-					conn->appname_state = APPNAME_STATE_CMD_SEND;
-					return PGRES_POLLING_WRITING;
-				}
 
 				/* Otherwise, we are open for business! */
 				conn->status = CONNECTION_OK;
@@ -1927,45 +1953,36 @@ keep_going:						/* We will come back to here until there is
 			}
 
 		case CONNECTION_SETENV:
+
+			/*
+			 * Do post-connection housekeeping (only needed in protocol 2.0).
+			 *
+			 * We pretend that the connection is OK for the duration of these
+			 * queries.
+			 */
+			conn->status = CONNECTION_OK;
+
+			switch (pqSetenvPoll(conn))
 			{
-				PostgresPollingStatusType ret;
+				case PGRES_POLLING_OK:	/* Success */
+					break;
 
-				/*
-				 * Do post-connection housekeeping (only needed in protocol
-				 * 2.0), or send the application name in PG8.5+.
-				 *
-				 * We pretend that the connection is OK for the duration of
-				 * these queries.
-				 */
-				conn->status = CONNECTION_OK;
+				case PGRES_POLLING_READING:		/* Still going */
+					conn->status = CONNECTION_SETENV;
+					return PGRES_POLLING_READING;
 
-				if (PG_PROTOCOL_MAJOR(conn->pversion) < 3)
-					ret = pqSetenvPoll(conn);
-				else				/* must be here to send app name */
-					ret = pqAppnamePoll(conn);
+				case PGRES_POLLING_WRITING:		/* Still going */
+					conn->status = CONNECTION_SETENV;
+					return PGRES_POLLING_WRITING;
 
-				switch (ret)
-				{
-					case PGRES_POLLING_OK:	/* Success */
-						break;
-
-					case PGRES_POLLING_READING:		/* Still going */
-						conn->status = CONNECTION_SETENV;
-						return PGRES_POLLING_READING;
-
-					case PGRES_POLLING_WRITING:		/* Still going */
-						conn->status = CONNECTION_SETENV;
-						return PGRES_POLLING_WRITING;
-
-					default:
-						goto error_return;
-				}
-
-				/* We are open for business! */
-				conn->status = CONNECTION_OK;
-				return PGRES_POLLING_OK;
+				default:
+					goto error_return;
 			}
 
+			/* We are open for business! */
+			conn->status = CONNECTION_OK;
+			return PGRES_POLLING_OK;
+
 		default:
 			appendPQExpBuffer(&conn->errorMessage,
 							  libpq_gettext("invalid connection state %d, "
@@ -2031,7 +2048,6 @@ makeEmptyPGconn(void)
 	conn->options_valid = false;
 	conn->nonblocking = false;
 	conn->setenv_state = SETENV_STATE_IDLE;
-	conn->appname_state = APPNAME_STATE_IDLE;
 	conn->client_encoding = PG_SQL_ASCII;
 	conn->std_strings = false;	/* unless server says differently */
 	conn->verbosity = PQERRORS_DEFAULT;
@@ -4048,129 +4064,6 @@ pqGetHomeDirectory(char *buf, int bufsize)
 #endif
 }
 
-/*
- *		pqAppnamePoll
- *
- * Polls the process of passing the application name to the backend.
- *
- * Ideally, we'd include the appname in the startup packet, but that would
- * cause old backends to reject the unknown parameter.  So we send it in a
- * separate query after we have determined the backend version.  Once there
- * is no interest in pre-8.5 backends, this should be folded into the startup
- * packet logic.
- */
-static PostgresPollingStatusType
-pqAppnamePoll(PGconn *conn)
-{
-	PGresult   *res;
-
-	if (conn == NULL || conn->status == CONNECTION_BAD)
-		return PGRES_POLLING_FAILED;
-
-	/* Check whether there is any data for us */
-	switch (conn->appname_state)
-	{
-			/* This is a reading state. */
-		case APPNAME_STATE_CMD_WAIT:
-		{
-			/* Load waiting data */
-			int			n = pqReadData(conn);
-
-			if (n < 0)
-				goto error_return;
-			if (n == 0)
-				return PGRES_POLLING_READING;
-
-			break;
-		}
-
-			/* This is a writing state, so we just proceed. */
-		case APPNAME_STATE_CMD_SEND:
-			break;
-
-			/* Should we raise an error if called when not active? */
-		case APPNAME_STATE_IDLE:
-			return PGRES_POLLING_OK;
-
-		default:
-			printfPQExpBuffer(&conn->errorMessage,
-							  libpq_gettext("invalid appname state %d, "
-											"probably indicative of memory corruption\n"),
-							  conn->appname_state);
-			goto error_return;
-	}
-
-	/* We will loop here until there is nothing left to do in this call. */
-	for (;;)
-	{
-		switch (conn->appname_state)
-		{
-			case APPNAME_STATE_CMD_SEND:
-			{
-				const char *val;
-				char	escVal[NAMEDATALEN*2 + 1];
-				char	setQuery[NAMEDATALEN*2 + 26 + 1];
-
-				/* Use appname if present, otherwise use fallback */
-				val = conn->appname ? conn->appname : conn->fbappname;
-
-				/*
-				 * Escape the data as needed.  We can truncate to NAMEDATALEN,
-				 * so there's no need to cope with malloc.
-				 */
-				PQescapeStringConn(conn, escVal, val, NAMEDATALEN, NULL);
-
-				sprintf(setQuery, "SET application_name = '%s'", escVal);
-
-				if (!PQsendQuery(conn, setQuery))
-					goto error_return;
-
-				conn->appname_state = APPNAME_STATE_CMD_WAIT;
-				break;
-			}
-
-			case APPNAME_STATE_CMD_WAIT:
-			{
-				if (PQisBusy(conn))
-					return PGRES_POLLING_READING;
-
-				res = PQgetResult(conn);
-
-				if (res)
-				{
-					if (PQresultStatus(res) != PGRES_COMMAND_OK)
-					{
-						PQclear(res);
-						goto error_return;
-					}
-					PQclear(res);
-					/* Keep reading until PQgetResult returns NULL */
-				}
-				else
-				{
-					/* Query finished, so we're done */
-					conn->appname_state = APPNAME_STATE_IDLE;
-					return PGRES_POLLING_OK;
-				}
-				break;
-			}
-
-			default:
-				printfPQExpBuffer(&conn->errorMessage,
-								  libpq_gettext("invalid appname state %d, "
-												"probably indicative of memory corruption\n"),
-								  conn->appname_state);
-				goto error_return;
-		}
-	}
-
-	/* Unreachable */
-
-error_return:
-	conn->appname_state = APPNAME_STATE_IDLE;
-	return PGRES_POLLING_FAILED;
-}
-
 /*
  * To keep the API consistent, the locking stubs are always provided, even
  * if they are not required.
diff --git a/src/interfaces/libpq/fe-protocol3.c b/src/interfaces/libpq/fe-protocol3.c
index 10e5edd756..bec8c019a8 100644
--- a/src/interfaces/libpq/fe-protocol3.c
+++ b/src/interfaces/libpq/fe-protocol3.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/interfaces/libpq/fe-protocol3.c,v 1.39 2009/06/11 14:49:14 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/interfaces/libpq/fe-protocol3.c,v 1.40 2009/12/02 04:38:35 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -1882,6 +1882,7 @@ build_startup_packet(const PGconn *conn, char *packet,
 {
 	int			packet_len = 0;
 	const PQEnvironmentOption *next_eo;
+	const char *val;
 
 	/* Protocol version comes first. */
 	if (packet)
@@ -1893,50 +1894,38 @@ build_startup_packet(const PGconn *conn, char *packet,
 	packet_len += sizeof(ProtocolVersion);
 
 	/* Add user name, database name, options */
+
+#define ADD_STARTUP_OPTION(optname, optval) \
+	do { \
+		if (packet) \
+			strcpy(packet + packet_len, optname); \
+		packet_len += strlen(optname) + 1; \
+		if (packet) \
+			strcpy(packet + packet_len, optval); \
+		packet_len += strlen(optval) + 1; \
+	} while(0)
+
 	if (conn->pguser && conn->pguser[0])
-	{
-		if (packet)
-			strcpy(packet + packet_len, "user");
-		packet_len += strlen("user") + 1;
-		if (packet)
-			strcpy(packet + packet_len, conn->pguser);
-		packet_len += strlen(conn->pguser) + 1;
-	}
+		ADD_STARTUP_OPTION("user", conn->pguser);
 	if (conn->dbName && conn->dbName[0])
-	{
-		if (packet)
-			strcpy(packet + packet_len, "database");
-		packet_len += strlen("database") + 1;
-		if (packet)
-			strcpy(packet + packet_len, conn->dbName);
-		packet_len += strlen(conn->dbName) + 1;
-	}
+		ADD_STARTUP_OPTION("database", conn->dbName);
 	if (conn->pgoptions && conn->pgoptions[0])
+		ADD_STARTUP_OPTION("options", conn->pgoptions);
+	if (conn->send_appname)
 	{
-		if (packet)
-			strcpy(packet + packet_len, "options");
-		packet_len += strlen("options") + 1;
-		if (packet)
-			strcpy(packet + packet_len, conn->pgoptions);
-		packet_len += strlen(conn->pgoptions) + 1;
+		/* Use appname if present, otherwise use fallback */
+		val = conn->appname ? conn->appname : conn->fbappname;
+		if (val && val[0])
+			ADD_STARTUP_OPTION("application_name", val);
 	}
 
 	/* Add any environment-driven GUC settings needed */
 	for (next_eo = options; next_eo->envName; next_eo++)
 	{
-		const char *val;
-
 		if ((val = getenv(next_eo->envName)) != NULL)
 		{
 			if (pg_strcasecmp(val, "default") != 0)
-			{
-				if (packet)
-					strcpy(packet + packet_len, next_eo->pgName);
-				packet_len += strlen(next_eo->pgName) + 1;
-				if (packet)
-					strcpy(packet + packet_len, val);
-				packet_len += strlen(val) + 1;
-			}
+				ADD_STARTUP_OPTION(next_eo->pgName, val);
 		}
 	}
 
diff --git a/src/interfaces/libpq/libpq-int.h b/src/interfaces/libpq/libpq-int.h
index a496aebbba..36d443970b 100644
--- a/src/interfaces/libpq/libpq-int.h
+++ b/src/interfaces/libpq/libpq-int.h
@@ -12,7 +12,7 @@
  * Portions Copyright (c) 1996-2009, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/interfaces/libpq/libpq-int.h,v 1.145 2009/11/28 23:38:08 tgl Exp $
+ * $PostgreSQL: pgsql/src/interfaces/libpq/libpq-int.h,v 1.146 2009/12/02 04:38:35 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -244,14 +244,6 @@ typedef enum
 	SETENV_STATE_IDLE
 } PGSetenvStatusType;
 
-/* PGAppnameStatusType defines the state of the PQAppname state machine */
-typedef enum
-{
-	APPNAME_STATE_CMD_SEND,		/* About to send the appname */
-	APPNAME_STATE_CMD_WAIT,		/* Waiting for above send to complete */
-	APPNAME_STATE_IDLE
-} PGAppnameStatusType;
-
 /* Typedef for the EnvironmentOptions[] array */
 typedef struct PQEnvironmentOption
 {
@@ -359,8 +351,8 @@ struct pg_conn
 	struct addrinfo *addr_cur;	/* the one currently being tried */
 	int			addrlist_family;	/* needed to know how to free addrlist */
 	PGSetenvStatusType setenv_state;	/* for 2.0 protocol only */
-	PGAppnameStatusType appname_state;
 	const PQEnvironmentOption *next_eo;
+	bool		send_appname;	/* okay to send application_name? */
 
 	/* Miscellaneous stuff */
 	int			be_pid;			/* PID of backend --- needed for cancels */