The appended patch addresses the outstanding issues of the recent guc patch.

It makes PGCLIENTENCODING work again and uses bsearch() instead of
iterating over the array of guc variables in guc_get_index().

Joachim Wieland

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 1.390 2007/05/04 01:13:44 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/utils/misc/guc.c,v 1.391 2007/05/08 16:33:51 petere Exp $
  *
  *--------------------------------------------------------------------
  */
@@ -2692,18 +2692,6 @@ add_guc_variable(struct config_generic * var, int elevel)
 	return true;
 }
 
-static int
-guc_get_index(const char *name)
-{
-	int i;
-
-	for (i = 0; i < num_guc_variables; i++)
-		if (guc_name_compare(name, guc_variables[i]->name) == 0)
-			return i;
-
-	return -1;
-}
-
 /*
  * Create and add a placeholder variable. It's presumed to belong
  * to a valid custom variable class at this point.
@@ -2843,6 +2831,30 @@ guc_name_compare(const char *namea, const char *nameb)
 }
 
 
+static int
+guc_get_index(const char *name)
+{
+	const char **key = &name;
+	struct config_generic **res;
+
+	Assert(name);
+
+	/*
+	 * By equating const char ** with struct config_generic *, we are assuming
+	 * the name field is first in config_generic.
+	 */
+	res = (struct config_generic **) bsearch((void *) &key,
+											 (void *) guc_variables,
+											 num_guc_variables,
+											 sizeof(struct config_generic *),
+											 guc_var_compare);
+	if (!res)
+		return -1;
+
+	return res - guc_variables;
+}
+
+
 /*
  * Initialize GUC options during program startup.
  *
@@ -4095,9 +4107,10 @@ set_config_option(const char *name, const char *value,
 	 * we can't set the variable itself.  There's one exception to
 	 * this rule: if we want to apply the default value to variables
 	 * that were removed from the configuration file.  This is
-	 * indicated by source == PGC_S_DEFAULT.
+	 * indicated by source == PGC_S_DEFAULT and context == PGC_SIGHUP.
 	 */
-	if (record->source > source && source != PGC_S_DEFAULT)
+	if (record->source > source
+		&& !(source == PGC_S_DEFAULT && context == PGC_SIGHUP))
 	{
 		if (changeVal && !makeDefault)
 		{