diff --git a/src/backend/optimizer/plan/initsplan.c b/src/backend/optimizer/plan/initsplan.c
index 9999eea4991..1a1c26adce8 100644
--- a/src/backend/optimizer/plan/initsplan.c
+++ b/src/backend/optimizer/plan/initsplan.c
@@ -1176,9 +1176,32 @@ make_outerjoininfo(PlannerInfo *root,
 	{
 		SpecialJoinInfo *otherinfo = (SpecialJoinInfo *) lfirst(l);
 
-		/* ignore full joins --- other mechanisms preserve their ordering */
+		/*
+		 * A full join is an optimization barrier: we can't associate into or
+		 * out of it.  Hence, if it overlaps either LHS or RHS of the current
+		 * rel, expand that side's min relset to cover the whole full join.
+		 */
 		if (otherinfo->jointype == JOIN_FULL)
+		{
+			if (bms_overlap(left_rels, otherinfo->syn_lefthand) ||
+				bms_overlap(left_rels, otherinfo->syn_righthand))
+			{
+				min_lefthand = bms_add_members(min_lefthand,
+											   otherinfo->syn_lefthand);
+				min_lefthand = bms_add_members(min_lefthand,
+											   otherinfo->syn_righthand);
+			}
+			if (bms_overlap(right_rels, otherinfo->syn_lefthand) ||
+				bms_overlap(right_rels, otherinfo->syn_righthand))
+			{
+				min_righthand = bms_add_members(min_righthand,
+												otherinfo->syn_lefthand);
+				min_righthand = bms_add_members(min_righthand,
+												otherinfo->syn_righthand);
+			}
+			/* Needn't do anything else with the full join */
 			continue;
+		}
 
 		/*
 		 * For a lower OJ in our LHS, if our join condition uses the lower
diff --git a/src/test/regress/expected/join.out b/src/test/regress/expected/join.out
index cafbc5e54d2..c8f864bfab2 100644
--- a/src/test/regress/expected/join.out
+++ b/src/test/regress/expected/join.out
@@ -3801,6 +3801,37 @@ where ss1.c2 = 0;
 ----+----+----+----+----+----
 (0 rows)
 
+--
+-- test successful handling of full join underneath left join (bug #14105)
+--
+explain (costs off)
+select * from
+  (select 1 as id) as xx
+  left join
+    (tenk1 as a1 full join (select 1 as id) as yy on (a1.unique1 = yy.id))
+  on (xx.id = coalesce(yy.id));
+              QUERY PLAN               
+---------------------------------------
+ Nested Loop Left Join
+   Join Filter: ((1) = COALESCE((1)))
+   ->  Result
+   ->  Hash Full Join
+         Hash Cond: (a1.unique1 = (1))
+         ->  Seq Scan on tenk1 a1
+         ->  Hash
+               ->  Result
+(8 rows)
+
+select * from
+  (select 1 as id) as xx
+  left join
+    (tenk1 as a1 full join (select 1 as id) as yy on (a1.unique1 = yy.id))
+  on (xx.id = coalesce(yy.id));
+ id | unique1 | unique2 | two | four | ten | twenty | hundred | thousand | twothousand | fivethous | tenthous | odd | even | stringu1 | stringu2 | string4 | id 
+----+---------+---------+-----+------+-----+--------+---------+----------+-------------+-----------+----------+-----+------+----------+----------+---------+----
+  1 |       1 |    2838 |   1 |    1 |   1 |      1 |       1 |        1 |           1 |         1 |        1 |   2 |    3 | BAAAAA   | EFEAAA   | OOOOxx  |  1
+(1 row)
+
 --
 -- test ability to push constants through outer join clauses
 --
diff --git a/src/test/regress/sql/join.sql b/src/test/regress/sql/join.sql
index 3430f918124..17293faa127 100644
--- a/src/test/regress/sql/join.sql
+++ b/src/test/regress/sql/join.sql
@@ -1209,6 +1209,23 @@ select ss2.* from
   lateral (select i41.*, i8.*, ss1.* from text_tbl limit 1) ss2
 where ss1.c2 = 0;
 
+--
+-- test successful handling of full join underneath left join (bug #14105)
+--
+
+explain (costs off)
+select * from
+  (select 1 as id) as xx
+  left join
+    (tenk1 as a1 full join (select 1 as id) as yy on (a1.unique1 = yy.id))
+  on (xx.id = coalesce(yy.id));
+
+select * from
+  (select 1 as id) as xx
+  left join
+    (tenk1 as a1 full join (select 1 as id) as yy on (a1.unique1 = yy.id))
+  on (xx.id = coalesce(yy.id));
+
 --
 -- test ability to push constants through outer join clauses
 --