diff --git a/manifest b/manifest
index 45f45fb98f..feef4be417 100644
--- a/manifest
+++ b/manifest
@@ -1,5 +1,5 @@
-C Modify\sthe\sOP_IfNotOpen\sopcode\sso\sthat\sthe\sjump\sis\staken\sif\sthe\scursor\sis\sopen\nbut\swas\spreviously\sset\sto\sa\sNULL\srow\susing\sOP_NullRow.
-D 2022-09-20T19:22:17.805
+C New\stest\scases\sfor\squery\sflattening\swhen\sthere\sare\sON\sclauses\sand\souter\sjoins.
+D 2022-09-20T19:45:04.738
 F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
 F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
 F LICENSE.md df5091916dbb40e6e9686186587125e1b2ff51f022cc334e886c19a0e9982724
@@ -1180,7 +1180,7 @@ F test/ioerr4.test f130fe9e71008577b342b8874d52984bd04ede2c
 F test/ioerr5.test 2edfa4fb0f896f733071303b42224df8bedd9da4
 F test/ioerr6.test a395a6ab144b26a9e3e21059a1ab6a7149cca65b
 F test/istrue.test e7f285bb70282625c258e866ce6337d4c762922f5a300e1b50f958aef6e7d9c9
-F test/join.test 21dbc65ab2476b10ae3ed1dcf64a99fb9a40473caa22f4cec2d6a829933c1442
+F test/join.test 41203c37d22e27b6b7211e3b1b875b6f0fc3c9fb2ea8fe31d3a8683ae3cf1a45
 F test/join2.test 466b07233820f5deee66a6c3bf6e4500c8bbf7b83649e67606f5f649c07928c0
 F test/join3.test 6f0c774ff1ba0489e6c88a3e77b9d3528fb4fda0
 F test/join4.test 1a352e4e267114444c29266ce79e941af5885916
@@ -2000,8 +2000,8 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P 852b385a5de622aa32026824210d4bd23db52a4a8a697b83d22d6000edeba487
-R 58d9f89a36d9e4cf587663a233307943
+P 1292d68caa7086610ddda343f3852e63de8da1eb66536ee4716b6529f5a31bc6
+R eab6511b05ba7254ebaf6e3422ee1bf8
 U drh
-Z 7e40ae1a3e52a669a3942bf4dda137ff
+Z 0a097f1ec50fb2c86025df8ed078e191
 # Remove this line to create a well-formed Fossil manifest.
diff --git a/manifest.uuid b/manifest.uuid
index 97e708724c..e88b85fddc 100644
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-1292d68caa7086610ddda343f3852e63de8da1eb66536ee4716b6529f5a31bc6
\ No newline at end of file
+db55387b1972bc7bc6855bd3497af744a111e7d28d09893cd985fbb01be41bcc
\ No newline at end of file
diff --git a/test/join.test b/test/join.test
index 82dbd447f9..8e7267d410 100644
--- a/test/join.test
+++ b/test/join.test
@@ -1130,5 +1130,63 @@ do_execsql_test join-27.5 {
     ) AS t99 ON b IN (1,2,3);
 } {}
 
+db null NULL
+do_execsql_test join-27.6 {
+  INSERT INTO t1 VALUES(3,4,NULL);
+  INSERT INTO t2 VALUES(1,2);
+  WITH t99(b) AS (
+    SELECT coalesce(b,3) FROM t2 AS x LEFT JOIN t1 ON c IN (SELECT x FROM t3)
+  )
+  SELECT d, e, b FROM t2 JOIN t99 ON b IN (1,2,3) ORDER BY +d;
+} {NULL NULL 3 NULL NULL 3 1 2 3 1 2 3}
+do_execsql_test join-27.7 {
+  SELECT d, e, b2
+    FROM t2 
+         JOIN (SELECT coalesce(b,3) AS b2 FROM t2 AS x LEFT JOIN t1
+                ON c IN (SELECT x FROM t3)) AS t99
+            ON b2 IN (1,2,3) ORDER BY +d;
+} {NULL NULL 3 NULL NULL 3 1 2 3 1 2 3}
+
+do_execsql_test join-27.8 {
+  DELETE FROM t1;
+  DELETE FROM t2 WHERE d IS NOT NULL;
+  DELETE FROM t3;
+  SELECT * FROM t2 JOIN (SELECT b FROM t2 LEFT JOIN t1
+                       ON c IN (SELECT x FROM t3)) AS t99 ON b IN (1,2,3);
+} {}
+
+# 2022-09-19 https://sqlite.org/forum/forumpost/96b9e5709cf47cda
+# Performance regression relative to version 3.38.0 that resulted from
+# a new query flattener restriction that was added to fixes the join-27.*
+# tests above.  The restriction needed to be removed and the join-27.*
+# problem fixed another way.
+#
+reset_db
+do_execsql_test join-28.1 {
+  CREATE TABLE t1(a INTEGER PRIMARY KEY, b INT, c INT);
+  CREATE TABLE t2(d INTEGER PRIMARY KEY, e INT);
+  CREATE VIEW t3(a,b,c,d,e) AS SELECT * FROM t1 LEFT JOIN t2 ON d=c;
+  CREATE TABLE t4(x INT, y INT);
+  INSERT INTO t1 VALUES(1,2,3);
+  INSERT INTO t2 VALUES(1,5);
+  INSERT INTO t4 VALUES(1,4);
+  SELECT a, b, y FROM t4 JOIN t3 ON a=x;
+} {1 2 4}
+do_eqp_test join-28.2 {
+  SELECT a, b, y FROM t4 JOIN t3 ON a=x;
+} {
+  QUERY PLAN
+  |--SCAN t4
+  `--SEARCH t1 USING INTEGER PRIMARY KEY (rowid=?)
+}
+# ^^^^^^^ Without the fix (if the query flattening optimization does not
+# run) the query plan above would look like this:
+#
+#   QUERY PLAN
+#   |--MATERIALIZE t3
+#   |  |--SCAN t1
+#   |  `--SEARCH t2 USING INTEGER PRIMARY KEY (rowid=?) LEFT-JOIN
+#   |--SCAN t4
+#   `--SEARCH t3 USING AUTOMATIC COVERING INDEX (a=?)
 
 finish_test