release-21.2: opt: do not cross-join input of semi-join

pkg/sql/logictest/testdata/logic_test/lookup_join

@@ -575,6 +575,36 @@ SELECT * FROM (VALUES (1), (2)) AS u(y) WHERE NOT EXISTS (
 1
 2
 
+# Regression test for #78681. Ensure that invalid lookup joins are not created
+# for semi joins.
+statement ok
+CREATE TABLE t78681 (
+  x INT NOT NULL CHECK (x in (1, 3)),
+  y INT NOT NULL,
+  PRIMARY KEY (x, y)
+)
+
+# Insert stats so that a lookup semi-join is selected.
+statement ok
+ALTER TABLE t78681 INJECT STATISTICS '[
+  {
+    "columns": ["x"],
+    "created_at": "2018-05-01 1:00:00.00000+00:00",
+    "row_count": 10000000,
+    "distinct_count": 2
+  }
+]'
+
+statement ok
+INSERT INTO t78681 VALUES (1, 1), (3, 1)
+
+query I rowsort
+SELECT * FROM (VALUES (1), (2)) AS u(y) WHERE EXISTS (
+  SELECT * FROM t78681 t WHERE u.y = t.y
+)
+----
+1
+
 statement ok
 CREATE TABLE lookup_expr (
   r STRING NOT NULL CHECK (r IN ('east', 'west')),

pkg/sql/logictest/testdata/logic_test/unique

@@ -274,7 +274,7 @@ INSERT INTO uniq_enum VALUES ('us-west', 'foo', 1, 1), ('eu-west', 'bar', 2, 2)
 # index, and the prefix of the index is an enum. This case uses the default
 # value for columns r and j.
 statement error pgcode 23505 pq: duplicate key value violates unique constraint "unique_i"\nDETAIL: Key \(i\)=\(1\) already exists\.
-INSERT INTO uniq_enum (s, i) VALUES ('foo', 1), ('bar', 2)
+INSERT INTO uniq_enum (s, i) VALUES ('foo', 1), ('bar', 3)
 
 query TTII colnames,rowsort
 SELECT * FROM uniq_enum