executor: set priority for IndexLookupExecutor when reading table (pi…

…ngcap#5288)

executor/distsql.go

@@ -617,6 +617,7 @@ func (e *IndexLookUpExecutor) buildTableReader(goCtx goctx.Context, handles []in
 		table:        e.table,
 		tableID:      e.tableID,
 		dagPB:        e.tableRequest,
+		priority:     e.priority,
 	}, handles)
 	if err != nil {
 		log.Error(err)

executor/executor_test.go

@@ -2039,15 +2039,23 @@ func (s *testContextOptionSuite) TestCoprocessorPriority(c *C) {
 	tk := testkit.NewTestKit(c, s.store)
 	tk.MustExec("use test")
 	tk.MustExec("create table t (id int primary key)")
+	tk.MustExec("create table t1 (id int, v int, unique index i_id (id))")
 	defer tk.MustExec("drop table t")
+	defer tk.MustExec("drop table t1")
 	tk.MustExec("insert into t values (1)")
 
+	// Insert some data to make sure plan build IndexLookup for t1.
+	for i := 0; i < 10; i++ {
+		tk.MustExec(fmt.Sprintf("insert into t1 values (%d, %d)", i, i))
+	}
+
 	cli := s.cli
 	cli.mu.Lock()
 	cli.mu.checkFlags = checkRequestPriority
 	cli.mu.Unlock()
 	cli.priority = pb.CommandPri_High
 	tk.MustQuery("select id from t where id = 1")
+	tk.MustQuery("select * from t1 where id = 1")
 
 	cli.priority = pb.CommandPri_Low
 	tk.MustQuery("select count(*) from t")