expression: check NotNullFlag of columns when simplifying binary operations

cmd/explaintest/r/explain_easy.result

@@ -387,7 +387,7 @@ Projection 5.00 root Column#17
  └─Selection 2.40 cop[tikv] eq(3, test.t.a)
  └─IndexRangeScan 3.00 cop[tikv] table:t1, index:idx(b) range:[3,3], keep order:true
 drop table if exists t;
-create table t(a int unsigned);
+create table t(a int unsigned not null);
 explain format = 'brief' select t.a = '123455' from t;
 id estRows task access object operator info
 Projection 10000.00 root eq(test.t.a, 123455)->Column#3

cmd/explaintest/t/explain_easy.test

@@ -71,7 +71,7 @@ explain format = 'brief' select t.c in (select count(*) from t s left join t t1
 explain format = 'brief' select t.c in (select count(*) from t s right join t t1 on s.a = t1.a where 3 = t.a and t1.b = 3) from t;
 
 drop table if exists t;
-create table t(a int unsigned);
+create table t(a int unsigned not null);
 explain format = 'brief' select t.a = '123455' from t;
 explain format = 'brief' select t.a > '123455' from t;
 explain format = 'brief' select t.a != '123455' from t;

expression/builtin_compare.go

@@ -1359,7 +1359,10 @@ func (c *compareFunctionClass) refineArgs(ctx sessionctx.Context, args []Express
  if !isExceptional || (isExceptional && mysql.HasNotNullFlag(arg0Type.Flag)) {
  finalArg1 = arg1
  }
- if isExceptional && arg1.GetType().EvalType() == types.ETInt && mysql.HasNotNullFlag(arg0Type.Flag) {
+ // TODO if the plan doesn't care about whether the result of the function is null or false, we don't need
+ // to check the NotNullFlag, then more optimizations can be enabled.
+ isExceptional = isExceptional && mysql.HasNotNullFlag(arg0Type.Flag)
+ if isExceptional && arg1.GetType().EvalType() == types.ETInt {
  // Judge it is inf or -inf
  // For int:
  // inf: 01111111 & 1 == 1
@@ -1380,7 +1383,10 @@ func (c *compareFunctionClass) refineArgs(ctx sessionctx.Context, args []Express
  if !isExceptional || (isExceptional && mysql.HasNotNullFlag(arg1Type.Flag)) {
  finalArg0 = arg0
  }
- if isExceptional && arg0.GetType().EvalType() == types.ETInt && mysql.HasNotNullFlag(arg1Type.Flag) {
+ // TODO if the plan doesn't care about whether the result of the function is null or false, we don't need
+ // to check the NotNullFlag, then more optimizations can be enabled.
+ isExceptional = isExceptional && mysql.HasNotNullFlag(arg1Type.Flag)
+ if isExceptional && arg0.GetType().EvalType() == types.ETInt {
  if arg0.Value.GetInt64()&1 == 1 {
  isNegativeInfinite = true
  } else {

expression/integration_test.go

@@ -9169,3 +9169,17 @@ func (s *testIntegrationSuite) TestIssue23889(c *C) {
  tk.MustQuery("SELECT ( test_decimal . `col_decimal` , test_decimal . `col_decimal` ) IN ( select * from test_t ) as field1 FROM test_decimal;").Check(
  testkit.Rows("<nil>", "0"))
 }
+
+func (s *testIntegrationSuite) TestRefineArgNullValues(c *C) {
+ defer s.cleanEnv(c)
+ tk := testkit.NewTestKit(c, s.store)
+ tk.MustExec("use test")
+ tk.MustExec("create table t(id int primary key, a int)")
+ tk.MustExec("create table s(a int)")
+ tk.MustExec("insert into s values(1),(2)")
+
+ tk.MustQuery("select t.id = 1.234 from t right join s on t.a = s.a").Check(testkit.Rows(
+ "<nil>",
+ "<nil>",
+ ))
+}

planner/core/integration_test.go

@@ -1073,7 +1073,7 @@ func (s *testIntegrationSuite) TestPartitionPruningForInExpr(c *C) {
 
  tk.MustExec("use test")
  tk.MustExec("drop table if exists t")
- tk.MustExec("create table t(a int(11), b int) partition by range (a) (partition p0 values less than (4), partition p1 values less than(10), partition p2 values less than maxvalue);")
+ tk.MustExec("create table t(a int(11) not null, b int) partition by range (a) (partition p0 values less than (4), partition p1 values less than(10), partition p2 values less than maxvalue);")
  tk.MustExec("insert into t values (1, 1),(10, 10),(11, 11)")
 
  var input []string