fix vector print (#20356)

fix vector print

Approved by: @triump2020

pkg/vm/engine/tae/common/print.go

@@ -259,7 +259,18 @@ func MoVectorToString(v *vector.Vector, printN int, opts ...TypePrintOpt) string
 		return vec2Str(vector.MustFixedColWithTypeCheck[types.Blockid](v)[:printN], v)
 	}
 	if v.GetType().IsVarlen() {
-		return vec2Str(vector.InefficientMustBytesCol(v)[:printN], v, opts...)
+		if !v.HasNull() {
+			return vec2Str(vector.InefficientMustBytesCol(v)[:printN], v, opts...)
+		}
+		vs := make([][]byte, 0, printN)
+		for i := 0; i < printN; i++ {
+			if v.GetNulls().Contains(uint64(i)) {
+				vs = append(vs, nil)
+			} else {
+				vs = append(vs, v.GetBytesAt(i))
+			}
+		}
+		return vec2Str(vs, v, opts...)
 	}
 	return fmt.Sprintf("unkown type vec... %v", *v.GetType())
 }

pkg/vm/engine/tae/db/test/db_test.go

@@ -19,6 +19,7 @@ import (
 	"context"
 	"errors"
 	"fmt"
+	"math"
 	"math/rand"
 	"reflect"
 	"sort"
@@ -81,6 +82,26 @@ const (
 	defaultGlobalCheckpointTimeout = 10 * time.Second
 )
 
+func TestPrintVector(t *testing.T) {
+	defer testutils.AfterTest(t)()
+	testutils.EnsureNoLeak(t)
+
+	mp, err := mpool.NewMPool("test", 0, mpool.NoFixed)
+	assert.NoError(t, err)
+	vec1 := vector.NewVec(types.T_uint32.ToType())
+	defer vec1.Free(mp)
+	for i := 0; i < 10; i++ {
+		err = vector.AppendFixed[uint32](vec1, math.MaxUint32, false, mp)
+		assert.NoError(t, err)
+	}
+
+	vec1.Reset(types.T_varchar.ToType())
+	err = vector.AppendBytes(vec1, nil, true, mp)
+	require.NoError(t, err)
+	s := common.MoVectorToString(vec1, 10)
+	t.Log(s)
+}
+
 func TestAppend1(t *testing.T) {
 	defer testutils.AfterTest(t)()
 	testutils.EnsureNoLeak(t)