Add doc entry for the new GUC paramenter enable_group_by_reordering

0452b461bc4 adds alternative orderings of group-by keys during the query
optimization. This new feature is controlled by the new GUC parameter
enable_group_by_reordering, which accidentally came without the documentation.
This commit adds the missing documentation for that GUC.

Reported-by: Bruce Momjian
Discussion: https://postgr.es/m/ZnDx2FYlba_OafQd%40momjian.us
Author: Andrei Lepikhov
Reviewed-by: Pavel Borisov, Alexander Korotkov

diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 698169afdb6aa7fee168de64d44deea8bcb24aa0..0c7a9082c549d1374ee222eb7a4a0fee07f10836 100644 (file)
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -5341,6 +5341,25 @@ ANY num_sync ( 
       
      
 
+     
+      enable_group_by_reordering (boolean)
+      
+       enable_group_by_reordering configuration parameter
+      
+      
+      
+       
+        Controls if the query planner will produce a plan which will provide
+        GROUP BY keys sorted in the order of keys of
+        a child node of the plan, such as an index scan.  When disabled, the
+        query planner will produce a plan with GROUP BY
+        keys only sorted to match the ORDER BY clause,
+        if any. When enabled, the planner will try to produce a more
+        efficient plan. The default value is on.
+       
+      
+     
+
      
       enable_hashagg (boolean)