Add CHANGES and release notes for #4411

It is worthwile mentioning the switch to qp-tries.

CHANGES

@@ -1,3 +1,25 @@
+6354.	[func]		The red-black tree data structure underlying the
+			RBTDB has been replaced with QP-tries.  This is
+			expected to improve scalability and reduce
+			CPU consumption under load. It is currently known to
+			have higher memory consumption than RBTDB; this
+			will be addressed in future releases.
+
+			Nodes in a QP-trie contain the full domain name,
+			while nodes in a red-black tree only contain names
+			relative to a parent.  Because of this difference,
+			zone files dumped with masterfile-style "relative"
+			will no longer have multiple different $ORIGIN
+			statements throughout the file.
+
+			This version is a minimal adaptation, keeping RBTDB
+			code largely unchanged, except as needed to replace
+			the underlying data structure. It uses the
+			single-thread "dns_qp" interface with locks for
+			synchronization. A future version will use the
+			multithreaded "dns_qpmulti" interface instead,
+			and will be renamed to QPDB. [GL #4411]
+
 6353.	[bug]		Improve the TTL-based cleaning by removing the expired
 			headers from the heap, so they don't block the next
 			cleaning round and clean more than a single item for
@@ -29,7 +51,8 @@
 6345.	[bug]		Added missing dns_rdataset_disassociate calls in
 			validator.c:findnsec3proofs. [GL #4571]
 
-6344.	[placeholder]
+6344.	[bug]		Fix case insensitive setting for isc_ht hashtable.
+			[GL #4568]
 
 6343.	[bug]		Fix case insensitive setting for isc_ht hashtable.
 			[GL #4568]

doc/notes/notes-current.rst

@@ -53,6 +53,18 @@ Feature Changes
   operationally required, then please consider using ``dnssec-validation auto``
   instead. :gl:`#4373`
 
+- The red-black tree data structure used in the RBTDB (the default
+  database implementation for cache and zone databases),
+  has been replaced with QP-tries.  This is expected to improve
+  performance and scalability, though in the current implementation
+  it is known to have larger memory consumption.
+
+  A side effect of this change is that zone files that are created with
+  :any:`masterfile-style` ``relative`` - for example, the output of
+  :any:`dnssec-signzone` - will no longer have multiple different
+  `$ORIGIN` statements. There should be no other behavior changes to
+  server behavior. :gl:`#4411`.
+
 Bug Fixes
 ~~~~~~~~~