Add support for an application_name parameter, which is displayed in

pg_stat_activity and recorded in log entries.

Dave Page, reviewed by Andres Freund

src/backend/utils/adt/pgstatfuncs.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/utils/adt/pgstatfuncs.c,v 1.54 2009/06/11 14:49:04 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/utils/adt/pgstatfuncs.c,v 1.55 2009/11/28 23:38:07 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -416,7 +416,7 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
 
 		oldcontext = MemoryContextSwitchTo(funcctx->multi_call_memory_ctx);
 
-		tupdesc = CreateTemplateTupleDesc(10, false);
+		tupdesc = CreateTemplateTupleDesc(11, false);
 		TupleDescInitEntry(tupdesc, (AttrNumber) 1, "datid", OIDOID, -1, 0);
 		TupleDescInitEntry(tupdesc, (AttrNumber) 2, "procpid", INT4OID, -1, 0);
 		TupleDescInitEntry(tupdesc, (AttrNumber) 3, "usesysid", OIDOID, -1, 0);
@@ -427,6 +427,7 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
 		TupleDescInitEntry(tupdesc, (AttrNumber) 8, "backend_start", TIMESTAMPTZOID, -1, 0);
 		TupleDescInitEntry(tupdesc, (AttrNumber) 9, "client_addr", INETOID, -1, 0);
 		TupleDescInitEntry(tupdesc, (AttrNumber) 10, "client_port", INT4OID, -1, 0);
+		TupleDescInitEntry(tupdesc, (AttrNumber) 11, "application_name", TEXTOID, -1, 0);
 
 		funcctx->tuple_desc = BlessTupleDesc(tupdesc);
 
@@ -478,8 +479,8 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
 	if (funcctx->call_cntr < funcctx->max_calls)
 	{
 		/* for each row */
-		Datum		values[10];
-		bool		nulls[10];
+		Datum		values[11];
+		bool		nulls[11];
 		HeapTuple	tuple;
 		PgBackendStatus *beentry;
 		SockAddr	zero_clientaddr;
@@ -599,6 +600,12 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
 					nulls[9] = true;
 				}
 			}
+
+			/* application name */
+			if (beentry->st_appname)
+			    values[10] = CStringGetTextDatum(beentry->st_appname);
+			else
+				nulls[10] = true;
 		}
 		else
 		{
@@ -610,6 +617,7 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
 			nulls[7] = true;
 			nulls[8] = true;
 			nulls[9] = true;
+			nulls[10] = true;
 		}
 
 		tuple = heap_form_tuple(funcctx->tuple_desc, values, nulls);

src/backend/utils/error/elog.c

@@ -42,7 +42,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/utils/error/elog.c,v 1.218 2009/10/17 00:24:50 mha Exp $
+ *	  $PostgreSQL: pgsql/src/backend/utils/error/elog.c,v 1.219 2009/11/28 23:38:07 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -68,6 +68,7 @@
 #include "storage/ipc.h"
 #include "storage/proc.h"
 #include "tcop/tcopprot.h"
+#include "utils/guc.h"
 #include "utils/memutils.h"
 #include "utils/ps_status.h"
 
@@ -1798,6 +1799,16 @@ log_line_prefix(StringInfo buf, ErrorData *edata)
 		/* process the option */
 		switch (Log_line_prefix[i])
 		{
+			case 'a':
+				if (MyProcPort)
+				{
+					const char *appname = application_name;
+
+					if (appname == NULL || *appname == '\0')
+						appname = _("[unknown]");
+					appendStringInfo(buf, "%s", appname);
+				}
+				break;
 			case 'u':
 				if (MyProcPort)
 				{
@@ -2103,6 +2114,11 @@ write_csvlog(ErrorData *edata)
 		appendCSVLiteral(&buf, msgbuf.data);
 		pfree(msgbuf.data);
 	}
+	appendStringInfoCharMacro(&buf, ',');
+
+	/* application name */
+	if (application_name)
+		appendCSVLiteral(&buf, application_name);
 
 	appendStringInfoChar(&buf, '\n');
 

src/backend/utils/misc/guc.c

@@ -10,7 +10,7 @@
  * Written by Peter Eisentraut <peter_e@gmx.net>.
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/utils/misc/guc.c,v 1.523 2009/10/21 20:38:58 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/utils/misc/guc.c,v 1.524 2009/11/28 23:38:07 tgl Exp $
  *
  *--------------------------------------------------------------------
  */
@@ -168,6 +168,7 @@ static bool assign_maxconnections(int newval, bool doit, GucSource source);
 static bool assign_autovacuum_max_workers(int newval, bool doit, GucSource source);
 static bool assign_effective_io_concurrency(int newval, bool doit, GucSource source);
 static const char *assign_pgstat_temp_directory(const char *newval, bool doit, GucSource source);
+static const char *assign_application_name(const char *newval, bool doit, GucSource source);
 
 static char *config_enum_get_options(struct config_enum * record,
 						const char *prefix, const char *suffix,
@@ -378,6 +379,8 @@ char	   *pgstat_temp_directory;
 
 char	   *default_do_language;
 
+char	   *application_name;
+
 int			tcp_keepalives_idle;
 int			tcp_keepalives_interval;
 int			tcp_keepalives_count;
@@ -2534,6 +2537,16 @@ static struct config_string ConfigureNamesString[] =
 		"plpgsql", NULL, NULL
 	},
 
+	{
+		{"application_name", PGC_USERSET, LOGGING,
+		 gettext_noop("Sets the application name to be reported in statistics and logs."),
+		 NULL,
+		 GUC_IS_NAME | GUC_NOT_IN_SAMPLE
+		},
+		&application_name,
+		"", assign_application_name, NULL
+	},
+
 	/* End-of-list marker */
 	{
 		{NULL, 0, 0, NULL, NULL}, NULL, NULL, NULL, NULL
@@ -7717,4 +7730,28 @@ assign_pgstat_temp_directory(const char *newval, bool doit, GucSource source)
 		return newval;
 }
 
+static const char *
+assign_application_name(const char *newval, bool doit, GucSource source)
+{
+	if (doit)
+	{
+		/* Only allow clean ASCII chars in the application name */
+		char	   *repval = guc_strdup(ERROR, newval);
+		char	   *p;
+
+		for (p = repval; *p; p++)
+		{
+			if (*p < 32 || *p > 126)
+				*p = '?';
+		}
+
+		/* Update the pg_stat_activity view */
+		pgstat_report_appname(repval);
+
+		return repval;
+	}
+	else
+		return newval;
+}
+
 #include "guc-file.c"

src/backend/utils/misc/postgresql.conf.sample

@@ -334,6 +334,7 @@
 #log_duration = off
 #log_hostname = off
 #log_line_prefix = ''			# special values:
+					#   %a = application name
 					#   %u = user name
 					#   %d = database name
 					#   %r = remote host and port