Recommit patch to allow commented GUC variables to return to their

default values.

src/backend/utils/misc/guc-file.l

@@ -4,7 +4,7 @@
  *
  * Copyright (c) 2000-2006, PostgreSQL Global Development Group
  *
- * $PostgreSQL: pgsql/src/backend/utils/misc/guc-file.l,v 1.43 2006/08/13 01:30:17 momjian Exp $
+ * $PostgreSQL: pgsql/src/backend/utils/misc/guc-file.l,v 1.44 2006/08/13 02:22:24 momjian Exp $
  */
 
 %{
@@ -117,6 +117,7 @@ ProcessConfigFile(GucContext context)
 {
 	int			elevel, i;
 	struct name_value_pair *item, *head, *tail;
+	char	   *env;
 	bool	   *apply_list = NULL;
 	int			varcount = 0;
 
@@ -183,6 +184,59 @@ ProcessConfigFile(GucContext context)
 			set_config_option(item->name, item->value, context,
 							  PGC_S_FILE, false, true);
 
+	if (context == PGC_SIGHUP)
+	{
+	/*
+	 * Revert all "untouched" options with reset source PGC_S_FILE to
+	 * default/boot value.
+	 */
+		for (i = 0; i < num_guc_variables; i++)
+		{
+			struct config_generic *gconf = guc_variables[i];
+
+			if (gconf->reset_source == PGC_S_FILE &&
+				 !(gconf->status & GUC_IN_CONFFILE))
+			{
+				if (gconf->context == PGC_BACKEND && IsUnderPostmaster)
+					; /* Be silent. Does any body want message from each session? */
+				else if (gconf->context == PGC_POSTMASTER)
+					ereport(elevel,
+						(errcode(ERRCODE_CANT_CHANGE_RUNTIME_PARAM),
+						errmsg("parameter \"%s\" cannot be changed (commented) after server start; configuration file change ignored",
+						gconf->name)));
+				else if (set_config_option(gconf->name, NULL, context,
+										   PGC_S_FILE, false, true))
+				{
+					GucStack   *stack;
+
+					gconf->reset_source = PGC_S_DEFAULT;
+
+					for (stack = gconf->stack; stack; stack = stack->prev)
+						if (stack->source == PGC_S_FILE)
+							stack->source = PGC_S_DEFAULT;
+
+					ereport(elevel,
+							(errcode(ERRCODE_SUCCESSFUL_COMPLETION),
+							errmsg("configuration option %s returned to default value", gconf->name)));
+				}
+			}
+			gconf->status &= ~GUC_IN_CONFFILE;
+		}
+
+		/*
+		 * Revert to environment variable. PGPORT is ignored, because it cannot be
+		 * set in running state.
+		 */
+		env = getenv("PGDATESTYLE");
+		if (env != NULL)
+			set_config_option("datestyle", env, context,
+							  PGC_S_ENV_VAR, false, true);
+
+		env = getenv("PGCLIENTENCODING");
+		if (env != NULL)
+			set_config_option("client_encoding", env, context,
+							PGC_S_ENV_VAR, false, true);
+	}
 
 cleanup_list:
 	if (apply_list)

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 1.338 2006/08/13 01:30:17 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/utils/misc/guc.c,v 1.339 2006/08/13 02:22:24 momjian Exp $
  *
  *--------------------------------------------------------------------
  */
@@ -2692,40 +2692,40 @@ InitializeGUCOptions(void)
 				{
 					struct config_bool *conf = (struct config_bool *) gconf;
 
-					if (conf->assign_hook)
+					if (conf->assign_hook &&
-						if (!(*conf->assign_hook) (conf->reset_val, true,
+						!(*conf->assign_hook) (conf->boot_val, true,
-												   PGC_S_DEFAULT))
+												PGC_S_DEFAULT))
-							elog(FATAL, "failed to initialize %s to %d",
+						elog(FATAL, "failed to initialize %s to %d",
-								 conf->gen.name, (int) conf->reset_val);
+							 conf->gen.name, (int) conf->boot_val);
-					*conf->variable = conf->reset_val;
+					*conf->variable = conf->reset_val = conf->boot_val;
 					break;
 				}
 			case PGC_INT:
 				{
 					struct config_int *conf = (struct config_int *) gconf;
 
-					Assert(conf->reset_val >= conf->min);
+					Assert(conf->boot_val >= conf->min);
-					Assert(conf->reset_val <= conf->max);
+					Assert(conf->boot_val <= conf->max);
-					if (conf->assign_hook)
+					if (conf->assign_hook &&
-						if (!(*conf->assign_hook) (conf->reset_val, true,
+						!(*conf->assign_hook) (conf->boot_val, true,
-												   PGC_S_DEFAULT))
+												PGC_S_DEFAULT))
-							elog(FATAL, "failed to initialize %s to %d",
+						elog(FATAL, "failed to initialize %s to %d",
-								 conf->gen.name, conf->reset_val);
+							 conf->gen.name, conf->boot_val);
-					*conf->variable = conf->reset_val;
+					*conf->variable = conf->reset_val = conf->boot_val; 
 					break;
 				}
 			case PGC_REAL:
 				{
 					struct config_real *conf = (struct config_real *) gconf;
 
-					Assert(conf->reset_val >= conf->min);
+					Assert(conf->boot_val >= conf->min);
-					Assert(conf->reset_val <= conf->max);
+					Assert(conf->boot_val <= conf->max);
-					if (conf->assign_hook)
+					if (conf->assign_hook &&
-						if (!(*conf->assign_hook) (conf->reset_val, true,
+						!(*conf->assign_hook) (conf->boot_val, true,
-												   PGC_S_DEFAULT))
+											   PGC_S_DEFAULT))
-							elog(FATAL, "failed to initialize %s to %g",
+						elog(FATAL, "failed to initialize %s to %g",
-								 conf->gen.name, conf->reset_val);
+							 conf->gen.name, conf->boot_val);
-					*conf->variable = conf->reset_val;
+					*conf->variable = conf->reset_val = conf->boot_val; 
 					break;
 				}
 			case PGC_STRING:
@@ -2738,10 +2738,8 @@ InitializeGUCOptions(void)
 					conf->tentative_val = NULL;
 
 					if (conf->boot_val == NULL)
-					{
 						/* Cannot set value yet */
 						break;
-					}
 
 					str = guc_strdup(FATAL, conf->boot_val);
 					conf->reset_val = str;
@@ -2753,10 +2751,8 @@ InitializeGUCOptions(void)
 						newstr = (*conf->assign_hook) (str, true,
 													   PGC_S_DEFAULT);
 						if (newstr == NULL)
-						{
 							elog(FATAL, "failed to initialize %s to \"%s\"",
 								 conf->gen.name, str);
-						}
 						else if (newstr != str)
 						{
 							free(str);
@@ -2796,12 +2792,10 @@ InitializeGUCOptions(void)
 	if (env != NULL)
 		SetConfigOption("port", env, PGC_POSTMASTER, PGC_S_ENV_VAR);
 
-	env = getenv("PGDATESTYLE");
+	if ((env = getenv("PGDATESTYLE")) != NULL)
-	if (env != NULL)
 		SetConfigOption("datestyle", env, PGC_POSTMASTER, PGC_S_ENV_VAR);
 
-	env = getenv("PGCLIENTENCODING");
+	if ((env = getenv("PGCLIENTENCODING")) != NULL)
-	if (env != NULL)
 		SetConfigOption("client_encoding", env, PGC_POSTMASTER, PGC_S_ENV_VAR);
 }
 
@@ -3178,7 +3172,7 @@ AtEOXact_GUC(bool isCommit, bool isSubXact)
 	for (i = 0; i < num_guc_variables; i++)
 	{
 		struct config_generic *gconf = guc_variables[i];
-		int			my_status = gconf->status;
+		int			my_status = gconf->status & (~GUC_IN_CONFFILE);
 		GucStack   *stack = gconf->stack;
 		bool		useTentative;
 		bool		changed;
@@ -3723,12 +3717,22 @@ parse_value(int elevel, const struct config_generic *record,
 				}
 				else
 				{
-					newval = conf->reset_val;
+					/*
-					*source = conf->gen.reset_source;
+					 * Revert value to default if source is configuration file. It is used when
+					 * configuration parameter is removed/commented out in the config file. Else
+					 * RESET or SET TO DEFAULT command is called and reset_val is used.
+					 */
+					if (*source == PGC_S_FILE)
+						newval =  conf->boot_val;
+					else
+					{
+						newval = conf->reset_val;
+						*source = conf->gen.reset_source;
+					}
 				}
 
-				if (conf->assign_hook)
+				if (conf->assign_hook &&
-					if (!(*conf->assign_hook) (newval, changeVal, *source))
+					!(*conf->assign_hook) (newval, changeVal, *source))
 					{
 						ereport(elevel,
 								(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
@@ -3767,8 +3771,18 @@ parse_value(int elevel, const struct config_generic *record,
 				}
 				else
 				{
-					newval = conf->reset_val;
+					/*
-					*source = conf->gen.reset_source;
+					 * Revert value to default if source is configuration file. It is used when
+					 * configuration parameter is removed/commented out in the config file. Else
+					 * RESET or SET TO DEFAULT command is called and reset_val is used.
+					 */
+					if (*source == PGC_S_FILE)
+						newval =  conf->boot_val;
+					else
+					{
+						newval = conf->reset_val;
+						*source = conf->gen.reset_source;
+					}
 				}
 
 				if (conf->assign_hook)
@@ -3811,12 +3825,22 @@ parse_value(int elevel, const struct config_generic *record,
 				}
 				else
 				{
-					newval = conf->reset_val;
+					/*
-					*source = conf->gen.reset_source;
+					 * Revert value to default if source is configuration file. It is used when
+					 * configuration parameter is removed/commented out in the config file. Else
+					 * RESET or SET TO DEFAULT command is called and reset_val is used.
+					 */
+					if (*source == PGC_S_FILE)
+						newval =  conf->boot_val;
+					else
+					{
+						newval = conf->reset_val;
+						*source = conf->gen.reset_source;
+					}
 				}
 
-				if (conf->assign_hook)
+				if (conf->assign_hook &&
-					if (!(*conf->assign_hook) (newval, changeVal, *source))
+					!(*conf->assign_hook) (newval, changeVal, *source))
 					{
 						ereport(elevel,
 								(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
@@ -3845,6 +3869,18 @@ parse_value(int elevel, const struct config_generic *record,
 					if (conf->gen.flags & GUC_IS_NAME)
 						truncate_identifier(newval, strlen(newval), true);
 				}
+				else if (*source == PGC_S_FILE)
+				{
+					/* Revert value to default when item is removed from config file. */
+					if (conf->boot_val != NULL)
+					{
+						newval = guc_strdup(elevel, conf->boot_val);
+						if (newval == NULL)
+							return false;
+					}
+					else
+						return false;
+				} 
 				else if (conf->reset_val)
 				{
 					/*
@@ -3856,10 +3892,8 @@ parse_value(int elevel, const struct config_generic *record,
 					*source = conf->gen.reset_source;
 				}
 				else
-				{
 					/* Nothing to reset to, as yet; so do nothing */
 					break;
-				}
 
 				if (conf->assign_hook)
 				{
@@ -4047,6 +4081,13 @@ verify_config_option(const char *name, const char *value,
 
 	if (parse_value(elevel, record, value, &source, false, NULL))
 	{
+		/*
+		 * Mark record like presented in the config file. Be carefull if
+		 * you use this function for another purpose than config file 
+		 * verification. It causes confusion configfile parser.
+		 */
+		record->status |= GUC_IN_CONFFILE;
+
 		if (isNewEqual != NULL)
 			*isNewEqual = is_newvalue_equal(record, value);
 		if (isContextOK != NULL)
@@ -4109,7 +4150,8 @@ set_config_option(const char *name, const char *value,
 	 * Should we set reset/stacked values?	(If so, the behavior is not
 	 * transactional.)
 	 */
-	makeDefault = changeVal && (source <= PGC_S_OVERRIDE) && (value != NULL);
+	makeDefault = changeVal && (source <= PGC_S_OVERRIDE) &&
+					(value != NULL || source == PGC_S_FILE);
 
 	/*
 	 * Ignore attempted set if overridden by previously processed setting.

src/include/utils/guc_tables.h

@@ -7,7 +7,7 @@
  *
  * Portions Copyright (c) 1996-2006, PostgreSQL Global Development Group
  *
- *	  $PostgreSQL: pgsql/src/include/utils/guc_tables.h,v 1.26 2006/08/12 04:11:50 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/include/utils/guc_tables.h,v 1.27 2006/08/13 02:22:24 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -143,7 +143,8 @@ struct config_generic
 #define GUC_HAVE_TENTATIVE	0x0001		/* tentative value is defined */
 #define GUC_HAVE_LOCAL		0x0002		/* a SET LOCAL has been executed */
 #define GUC_HAVE_STACK		0x0004		/* we have stacked prior value(s) */
-
+#define GUC_IN_CONFFILE		0x0008		/* value shows up in the configuration
+										   file (is not commented) */
 
 /* GUC records for specific variable types */
 
@@ -153,11 +154,12 @@ struct config_bool
 	/* these fields must be set correctly in initial value: */
 	/* (all but reset_val are constants) */
 	bool	   *variable;
-	bool		reset_val;
+	bool		boot_val;
 	GucBoolAssignHook assign_hook;
 	GucShowHook show_hook;
 	/* variable fields, initialized at runtime: */
 	bool		tentative_val;
+	bool		reset_val;
 };
 
 struct config_int
@@ -166,13 +168,14 @@ struct config_int
 	/* these fields must be set correctly in initial value: */
 	/* (all but reset_val are constants) */
 	int		   *variable;
-	int			reset_val;
+	int			boot_val;
 	int			min;
 	int			max;
 	GucIntAssignHook assign_hook;
 	GucShowHook show_hook;
 	/* variable fields, initialized at runtime: */
 	int			tentative_val;
+	int			reset_val;
 };
 
 struct config_real
@@ -181,13 +184,14 @@ struct config_real
 	/* these fields must be set correctly in initial value: */
 	/* (all but reset_val are constants) */
 	double	   *variable;
-	double		reset_val;
+	double		boot_val;
 	double		min;
 	double		max;
 	GucRealAssignHook assign_hook;
 	GucShowHook show_hook;
 	/* variable fields, initialized at runtime: */
 	double		tentative_val;
+	double		reset_val;
 };
 
 struct config_string