Make the startup_data queries more robust.

The connection shouldn't fail because the usual data is not available.

Author: James William Pye

postgresql/driver/pq3.py

@@ -2050,21 +2050,22 @@ def connect(self):
 		# manual binding
 		self.sys = pg_lib.Binding(self, pg_lib.sys)
 
-		if self.version_info[:2] <= (8,0):
-			meth = self.sys.startup_data_only_version
+		vi = self.version_info[:2]
+		if vi <= (8,1):
+			sd = self.sys.startup_data_only_version()
 		else:
-			meth = self.sys.startup_data
+			sd = self.sys.startup_data()
 		# connection info
 		self.version, self.backend_start, \
-		self.client_address, self.client_port = meth()
+		self.client_address, self.client_port = sd
 
 		# First word from the version string.
 		self.type = self.version.split()[0]
 
 		##
 		# Set standard_conforming_strings
 		scstr = self.settings.get('standard_conforming_strings')
-		if scstr is None or (self.version_info[0] == 8 and self.version_info[1] == 1):
+		if scstr is None or vi == (8,1):
 			# There used to be a warning emitted here.
 			# It was noisy, and had little added value
 			# over a nice WARNING at the top of the driver documentation.

postgresql/lib/libsys.sql

@@ -115,27 +115,37 @@ FROM
 	pg_catalog.generate_series(1, array_upper(($1::text[][]), 1)) g(i)
 
 [startup_data:transient:first]
+-- 8.2 and greater
 SELECT
- pg_catalog.version()::text,
+ pg_catalog.version()::text AS version,
  backend_start::text,
  client_addr::text,
- client_port
-FROM pg_catalog.pg_stat_activity WHERE procpid = pg_catalog.pg_backend_pid();
+ client_port::int
+FROM pg_catalog.pg_stat_activity WHERE procpid = pg_catalog.pg_backend_pid()
+UNION ALL SELECT
+ pg_catalog.version()::text AS version,
+ NULL::text AS backend_start,
+ NULL::text AS client_addr,
+ NULL::int AS client_port
+LIMIT 1;
 
 [startup_data_no_start:transient:first]
+-- 8.1 only, but is unused as often the backend's activity row is not
+-- immediately present.
 SELECT
- pg_catalog.version()::text,
+ pg_catalog.version()::text AS version,
  NULL::text AS backend_start,
  client_addr::text,
- client_port
+ client_port::int
 FROM pg_catalog.pg_stat_activity WHERE procpid = pg_catalog.pg_backend_pid();
 
 [startup_data_only_version:transient:first]
+-- In 8.0, there's nothing there.
 SELECT
- pg_catalog.version()::text,
+ pg_catalog.version()::text AS version,
  NULL::text AS backend_start,
  NULL::text AS client_addr,
- NULL::text AS client_port;
+ NULL::int AS client_port;
 
 [sizeof_db:transient:first]
 SELECT pg_catalog.pg_database_size(current_database())::bigint