*: bypass order by clause for fast point get plan (#50204) (#50364)

close #49920

cmd/explaintest/r/explain_easy_stats.result

@@ -179,7 +179,9 @@ id	estRows	task	access object	operator info
 Point_Get	1.00	root	table:index_prune, index:PRIMARY(a, b)	
 explain format = 'brief' select * from index_prune WHERE a = 1010010404050976781 AND b = 26467085526790 GROUP BY b ORDER BY a limit 1;
 id	estRows	task	access object	operator info
-Point_Get	1.00	root	table:index_prune, index:PRIMARY(a, b)	
+TopN	1.00	root		test.index_prune.a, offset:0, count:1
+└─StreamAgg	1.00	root		group by:test.index_prune.b, funcs:firstrow(test.index_prune.a)->test.index_prune.a, funcs:firstrow(test.index_prune.b)->test.index_prune.b, funcs:firstrow(test.index_prune.c)->test.index_prune.c
+  └─Point_Get	1.00	root	table:index_prune, index:PRIMARY(a, b)	
 drop table if exists t1, t2, t3, index_prune;
 set @@session.tidb_opt_insubq_to_join_and_agg=1;
 drop table if exists tbl;

executor/executor_test.go

@@ -4999,6 +4999,14 @@ func TestIsPointGet(t *testing.T) {
 	}
 }
 
+func TestPointGetOrderby(t *testing.T) {
+	store := testkit.CreateMockStore(t)
+	tk := testkit.NewTestKit(t, store)
+	tk.MustExec("use test")
+	tk.MustExec("create table t (i int key)")
+	require.Equal(t, tk.ExecToErr("select * from t where i = 1 order by j limit 10;").Error(), "[planner:1054]Unknown column 'j' in 'order clause'")
+}
+
 func TestClusteredIndexIsPointGet(t *testing.T) {
 	store := testkit.CreateMockStore(t)
 	tk := testkit.NewTestKit(t, store)

planner/core/point_get_plan.go

@@ -1012,7 +1012,7 @@ func tryWhereIn2BatchPointGet(ctx sessionctx.Context, selStmt *ast.SelectStmt) *
 // 3. All the columns must be public and not generated.
 // 4. The condition is an access path that the range is a unique key.
 func tryPointGetPlan(ctx sessionctx.Context, selStmt *ast.SelectStmt, check bool) *PointGetPlan {
-	if selStmt.Having != nil {
+	if selStmt.Having != nil || selStmt.OrderBy != nil {
 		return nil
 	} else if selStmt.Limit != nil {
 		count, offset, err := extractLimitCountOffset(ctx, selStmt.Limit)