fix(optimizer)!: simplify connector complements only for non-null operands

sqlglot/optimizer/annotate_types.py

@@ -441,6 +441,10 @@ def _annotate_binary(self, expression: B) -> B:
 
         if isinstance(expression, (exp.Connector, exp.Predicate)):
             self._set_type(expression, exp.DataType.Type.BOOLEAN)
+            if isinstance(expression, exp.Is) or (
+                left.meta.get("nullable") is False and right.meta.get("nullable") is False
+            ):
+                expression.meta["nullable"] = False
         elif (left_type, right_type) in self.binary_coercions:
             self._set_type(expression, self.binary_coercions[(left_type, right_type)](left, right))
         else:
@@ -456,6 +460,9 @@ def _annotate_unary(self, expression: E) -> E:
         else:
             self._set_type(expression, expression.this.type)
 
+        if expression.this.meta.get("nullable") is False:
+            expression.meta["nullable"] = False
+
         return expression
 
     def _annotate_literal(self, expression: exp.Literal) -> exp.Literal:
@@ -466,6 +473,8 @@ def _annotate_literal(self, expression: exp.Literal) -> exp.Literal:
         else:
             self._set_type(expression, exp.DataType.Type.DOUBLE)
 
+        expression.meta["nullable"] = False
+
         return expression
 
     def _annotate_with_type(

sqlglot/optimizer/simplify.py

@@ -395,14 +395,15 @@ def remove_complements(expression, root=True):
     """
     Removing complements.
 
-    A AND NOT A -> FALSE
-    A OR NOT A -> TRUE
+    A AND NOT A -> FALSE (only for non-NULL literals)
+    A OR NOT A -> TRUE (only for non-NULL literals)
     """
     if isinstance(expression, AND_OR) and (root or not expression.same_parent):
         ops = set(expression.flatten())
         for op in ops:
             if isinstance(op, exp.Not) and op.this in ops:
-                return exp.false() if isinstance(expression, exp.And) else exp.true()
+                if expression.meta.get("nullable") is False:
+                    return exp.false() if isinstance(expression, exp.And) else exp.true()
 
     return expression
 

tests/fixtures/optimizer/simplify.sql

@@ -8,10 +8,10 @@ y OR y;
 y;
 
 x AND NOT x;
-FALSE;
+NOT x AND x;
 
 x OR NOT x;
-TRUE;
+NOT x OR x;
 
 1 AND TRUE;
 TRUE;
@@ -299,7 +299,7 @@ A XOR D XOR B XOR E XOR F XOR G XOR C;
 A XOR B XOR C XOR D XOR E XOR F XOR G;
 
 A AND NOT B AND C AND B;
-FALSE;
+A AND B AND C AND NOT B;
 
 (a AND b AND c AND d) AND (d AND c AND b AND a);
 a AND b AND c AND d;
@@ -892,7 +892,7 @@ COALESCE(x, 1) = 1;
 x = 1 OR x IS NULL;
 
 COALESCE(x, 1) IS NULL;
-FALSE;
+NOT x IS NULL AND x IS NULL;
 
 COALESCE(ROW() OVER (), 1) = 1;
 ROW() OVER () = 1 OR ROW() OVER () IS NULL;
@@ -1344,3 +1344,30 @@ WITH t0 AS (SELECT 1 AS a, 'foo' AS p) SELECT NOT NOT CASE WHEN t0.a > 1 THEN t0
 # dialect: sqlite
 WITH t0 AS (SELECT 1 AS a, 'foo' AS p) SELECT NOT (NOT(CASE WHEN t0.a > 1 THEN t0.a ELSE t0.p END)) AS res FROM t0;
 WITH t0 AS (SELECT 1 AS a, 'foo' AS p) SELECT NOT NOT CASE WHEN t0.a > 1 THEN t0.a ELSE t0.p END AS res FROM t0;
+
+--------------------------------------
+-- Simplify complements
+--------------------------------------
+TRUE OR NOT TRUE;
+TRUE;
+
+TRUE AND NOT TRUE;
+FALSE;
+
+'a' OR NOT 'a';
+TRUE;
+
+'a' AND NOT 'a';
+FALSE;
+
+100 OR NOT 100;
+TRUE;
+
+100 AND NOT 100;
+FALSE;
+
+NULL OR NOT NULL;
+NULL;
+
+NULL AND NOT NULL;
+NULL;

tests/test_optimizer.py

@@ -1699,3 +1699,51 @@ def test_annotate_object_construct(self):
         self.assertEqual(
             annotated.selects[0].type.sql("snowflake"), 'OBJECT("foo" VARCHAR, "a b" VARCHAR)'
         )
+
+    def test_nullable_annotation(self):
+        for literal_sql in ("1", "'foo'", "2.5"):
+            with self.subTest(f"Test NULL annotation for literal: {literal_sql}"):
+                sql = f"SELECT {literal_sql}"
+                query = parse_one(sql)
+                annotated = annotate_types(query)
+                assert annotated.selects[0].meta.get("nullable") is False
+
+        schema = {"foo": {"id": "INT"}}
+
+        for predicate in (">", "<", ">=", "<=", "=", "!=", "<>", "LIKE", "NOT LIKE"):
+            for operand, nullable in (("1", False), ("foo.id", None)):
+                sql_predicate = f"{operand} {predicate} {operand}"
+                with self.subTest(f"Test NULL propagation for predicate: {predicate}"):
+                    sql = f"SELECT {sql_predicate} FROM foo"
+                    query = parse_one(sql)
+                    annotated = annotate_types(query, schema=schema)
+                    assert annotated.selects[0].meta.get("nullable") is nullable
+
+        for predicate in ("IS NULL", "IS NOT NULL"):
+            sql_predicate = f"foo.id {predicate}"
+            with self.subTest(f"Test NULL propagation for predicate: {predicate}"):
+                sql = f"SELECT {sql_predicate} FROM foo"
+                query = parse_one(sql)
+                annotated = annotate_types(query, schema=schema)
+                assert annotated.selects[0].meta.get("nullable") is False
+
+        for connector in ("AND", "OR"):
+            for predicate in (">", "<", ">=", "<=", "=", "!=", "<>", "LIKE", "NOT LIKE"):
+                for operand, nullable in (("1", False), ("foo.id", None)):
+                    sql_predicate = f"({operand} {predicate} {operand})"
+                    sql_connector = f"{sql_predicate} {connector} {sql_predicate}"
+                    with self.subTest(
+                        f"Test NULL propagation for connector: {connector} with predicates: {predicate}"
+                    ):
+                        sql = f"SELECT {sql_connector} FROM foo"
+                        query = parse_one(sql)
+                        annotated = annotate_types(query, schema=schema)
+                        assert annotated.selects[0].meta.get("nullable") is nullable
+
+        for unary in ("NOT", "-"):
+            for value, nullable in (("1", False), ("foo.id", None)):
+                with self.subTest(f"Test NULL propagation for unary: {unary} with value: {value}"):
+                    sql = f"SELECT {unary} {value} FROM foo"
+                    query = parse_one(sql)
+                    annotated = annotate_types(query, schema=schema)
+                    assert annotated.selects[0].meta.get("nullable") is nullable