IterReverse does not return data when k is nil #1781
Description
When calling IterReverse with nil as parameter k, the returned data is empty.
Is this because TiKV does not support this type of scan or is it a driver bug?
The code to reproduce this is as follows:
package main
import (
"context"
"fmt"
"github.com/tikv/client-go/v2/txnkv"
)
func PrefixNextKey(k []byte) []byte {
buf := make([]byte, len(k))
copy(buf, k)
var i int
for i = len(k) - 1; i >= 0; i-- {
buf[i]++
if buf[i] != 0 {
break
}
}
if i == -1 {
buf = make([]byte, 0)
}
return buf
}
func main() {
var err error
pd, err := txnkv.NewClient([]string{"127.0.0.1:2379"})
if err != nil {
panic(err)
}
defer pd.Close()
func() {
txn, err := pd.Begin()
if err != nil {
panic(err)
}
txn.Set([]byte("b_i100005_00000001_08"), []byte("1"))
txn.Set([]byte("b_i100005_00000002_07"), []byte("2"))
txn.Set([]byte("b_i100005_00000003_06"), []byte("3"))
txn.Set([]byte("b_i100005_00000004_05"), []byte("4"))
txn.Set([]byte("b_i100005_00000005_04"), []byte("5"))
txn.Set([]byte("b_i100005_00000006_03"), []byte("6"))
txn.Set([]byte("b_i100005_00000007_02"), []byte("7"))
txn.Set([]byte("b_i100005_00000008_01"), []byte("8"))
defer func() {
err := txn.Commit(context.TODO())
if err != nil {
panic(err)
}
}()
}()
func() {
timestamp, err := pd.CurrentTimestamp("")
if err != nil {
panic(err)
}
snapshot := pd.GetSnapshot(timestamp)
k := PrefixNextKey([]byte("b_i100005_00000005"))
lowerBound := PrefixNextKey([]byte("b_i100005_00000001"))
func() {
fmt.Printf("================================\n..%v\n", string(k))
iter, err := snapshot.IterReverse(k, nil)
if err != nil {
panic(err)
}
defer iter.Close()
for iter.Valid() {
fmt.Printf("%v=%v\n", string(iter.Key()), string(iter.Value()))
iter.Next()
}
fmt.Println("================================")
}()
func() {
fmt.Printf("================================\n%v..\n", string(lowerBound))
iter, err := snapshot.IterReverse(nil, lowerBound)
if err != nil {
panic(err)
}
defer iter.Close()
for iter.Valid() {
fmt.Printf("%v=%v\n", string(iter.Key()), string(iter.Value()))
iter.Next()
}
fmt.Println("================================")
}()
// output:
// ================================
// ..b_i100005_00000006
// b_i100005_00000005_04=5
// b_i100005_00000004_05=4
// b_i100005_00000003_06=3
// b_i100005_00000002_07=2
// b_i100005_00000001_08=1
// ================================
// ================================
// b_i100005_00000002..
// ================================
}()
}TiKV: v8.5.3
client-go: v2.0.8-0.20251028065425-b7d4dfd8520e