Index: doc/src/sgml/config.sgml
===================================================================
--- doc/src/sgml/config.sgml	(revision 30152)
+++ doc/src/sgml/config.sgml	(working copy)
@@ -2281,6 +2281,20 @@
       </listitem>
      </varlistentry>
 
+     <varlistentry id="guc-cursor-tuple-fraction" xreflabel="cursor_tuple_fraction">
+      <term><varname>cursor_tuple_fraction</varname> (<type>floating point</type>)</term>
+      <indexterm>
+       <primary><varname>cursor_tuple_fraction</> configuration parameter</primary>
+      </indexterm>
+      <listitem>
+       <para>
+        Sets the planner's estimate of how many rows of a cursor will
+        be retrieved by fetches. This affects the planner's favor to 
+        use fast-start plans for cursor. The default is 0.1.
+       </para>
+      </listitem>
+     </varlistentry>
+
      </variablelist>
     </sect2>
    </sect1>
Index: src/backend/optimizer/plan/planner.c
===================================================================
--- src/backend/optimizer/plan/planner.c	(revision 30152)
+++ src/backend/optimizer/plan/planner.c	(working copy)
@@ -42,6 +42,9 @@
 #include "utils/syscache.h"
 
 
+/* GUC parameter cursor_tuple_fraction */
+double cursor_tuple_fraction = DEFAULT_CURSOR_TUPLE_FRACTION;
+
 /* Hook for plugins to get control in planner() */
 planner_hook_type planner_hook = NULL;
 
@@ -143,10 +146,9 @@
 		/*
 		 * We have no real idea how many tuples the user will ultimately FETCH
 		 * from a cursor, but it seems a good bet that he doesn't want 'em
-		 * all.  Optimize for 10% retrieval (you gotta better number?  Should
-		 * this be a SETtable parameter?)
+		 * all. Optimize for 10% retrieval per default. Is a GUC parameter.
 		 */
-		tuple_fraction = 0.10;
+		tuple_fraction = cursor_tuple_fraction;
 	}
 	else
 	{
Index: src/backend/utils/misc/guc.c
===================================================================
--- src/backend/utils/misc/guc.c	(revision 30152)
+++ src/backend/utils/misc/guc.c	(working copy)
@@ -1884,6 +1884,15 @@
 		0.5, 0.0, 1.0, NULL, NULL
 	},
 
+	{
+		{"cursor_tuple_fraction", PGC_USERSET, QUERY_TUNING_OTHER,
+			gettext_noop("Sets the tuple fraction for cursors."),
+			NULL
+		},
+		&cursor_tuple_fraction,
+		DEFAULT_CURSOR_TUPLE_FRACTION, 0.0, 1.0, NULL, NULL
+	},
+
 	/* End-of-list marker */
 	{
 		{NULL, 0, 0, NULL, NULL}, NULL, 0.0, 0.0, 0.0, NULL, NULL
Index: src/backend/utils/misc/postgresql.conf.sample
===================================================================
--- src/backend/utils/misc/postgresql.conf.sample	(revision 30152)
+++ src/backend/utils/misc/postgresql.conf.sample	(working copy)
@@ -223,6 +223,7 @@
 #from_collapse_limit = 8
 #join_collapse_limit = 8		# 1 disables collapsing of explicit 
 					# JOIN clauses
+#cursor_tuple_fraction = 0.1		# range 0.0-1.0
 
 
 #------------------------------------------------------------------------------
Index: src/include/optimizer/planmain.h
===================================================================
--- src/include/optimizer/planmain.h	(revision 30152)
+++ src/include/optimizer/planmain.h	(working copy)
@@ -18,6 +18,12 @@
 #include "nodes/relation.h"
 
 /*
+ * GUC parameter cursor_tuple_fraction
+ */
+#define DEFAULT_CURSOR_TUPLE_FRACTION 0.1
+extern double cursor_tuple_fraction;
+
+/*
  * prototypes for plan/planmain.c
  */
 extern void query_planner(PlannerInfo *root, List *tlist,