Add upgrade note about change in default result order. refs #18943

Arvados-DCO-1.1-Signed-off-by: Peter Amstutz <peter.amstutz@curii.com>

diff --git a/doc/admin/upgrading.html.textile.liquid b/doc/admin/upgrading.html.textile.liquid
index 97f6ce2f89756dc6decb4f8863655af4b2982cb4..7e36088c636bad036dae7a05b139dcfd91535181 100644 (file)
--- a/doc/admin/upgrading.html.textile.liquid
+++ b/doc/admin/upgrading.html.textile.liquid
@@ -30,10 +30,14 @@ TODO: extract this information based on git commit messages and generate changel
 
 h2(#main). development main (as of 2022-03-??)
 
-h2(#v2_4_0). v2.4.0 (2022-03-??)
+h2(#v2_4_0). v2.4.0 (2022-04-??)
 
 "previous: Upgrading to 2.3.1":#v2_3_1
 
+h3. Default result order changed
+
+When requesting a list of objects without an explicit @order@ parameter, the default order has changed from @modified_at desc, uuid asc@ to @modified_at desc, uuid desc@.  This means that if two objects have identical @modified_at@ timestamps, the tiebreaker will now be based on @uuid@ in decending order where previously it would be ascending order. The practical effect of this should be minor; with microsecond precision it is unusual to have two records with exactly the same timestamp, and order-sensitive queries should already provide an explicit @order@ parameter.
+
 h3. Ubuntu 18.04 Arvados Python packages now depend on python-3.8
 
 Ubuntu 18.04 ships with Python 3.6 as the default version of Python 3. Ubuntu also ships a version of Python 3.8, and the Arvados Python packages (@python3-arvados-cwl-runner@, @python3-arvados-fuse@, @python3-arvados-python-client@, @python3-arvados-user-activity@ and @python3-crunchstat-summary@) now depend on the @python-3.8@ system package.