func getIndexRowFromRange(idxInfo *tipb.IndexInfo, txn kv.Transaction, ran kv.KeyRange, desc bool, limit int64) ([]*tipb.Row, error) {
var rows []*tipb.Row
var seekKey kv.Key
if desc {
seekKey = ran.EndKey
} else {
seekKey = ran.StartKey
}
for {
if limit == 0 {
break
}
var it kv.Iterator
var err error
if desc {
it, err = txn.SeekReverse(seekKey)
if err != nil {
return nil, errors.Trace(err)
}
seekKey = it.Key()
} else {
it, err = txn.Seek(seekKey)
if err != nil {
return nil, errors.Trace(err)
}
seekKey = it.Key().PrefixNext()
}
if !it.Valid() {
break
}
if desc {
if it.Key().Cmp(ran.StartKey) < 0 {
break
}
} else {
if it.Key().Cmp(ran.EndKey) >= 0 {
break
}
}
datums, err := tablecodec.DecodeIndexKey(it.Key())
if err != nil {
return nil, errors.Trace(err)
}
var handle types.Datum
if len(datums) > len(idxInfo.Columns) {
handle = datums[len(idxInfo.Columns)]
datums = datums[:len(idxInfo.Columns)]
} else {
var intHandle int64
intHandle, err = decodeHandle(it.Value())
if err != nil {
return nil, errors.Trace(err)
}
handle.SetInt64(intHandle)
}
data, err := codec.EncodeValue(nil, datums...)
if err != nil {
return nil, errors.Trace(err)
}
handleData, err := codec.EncodeValue(nil, handle)
if err != nil {
return nil, errors.Trace(err)
}
row := &tipb.Row{Handle: handleData, Data: data}
rows = append(rows, row)
limit--
}
return rows, nil
}