var filledEntries []fileservice.IOEntry
putFillHolder := func(i int, seqnum uint16) {
	if filledEntries == nil {
		filledEntries = make([]fileservice.IOEntry, len(seqnums))
	}
	filledEntries[i] = fileservice.IOEntry{
		Size: int64(seqnum), // a marker, it can not be zero
	}
}
blkmeta := meta.GetBlockMeta(uint32(blk))
maxSeqnum := blkmeta.GetMaxSeqnum()
for i, seqnum := range seqnums {
	// special columns
	if seqnum >= SEQNUM_UPPER {
		metaColCnt := blkmeta.GetMetaColumnCount()
		switch seqnum {
		case SEQNUM_COMMITTS:
			seqnum = metaColCnt - 1
		case SEQNUM_ABORT:
			panic("not support")
		default:
			panic(fmt.Sprintf("bad path to read special column %d", seqnum))
		}
		// if the last column is not commits, do not read it
		// 1. created by cn
		// 2. old version tn nonappendable block
		col := blkmeta.ColumnMeta(seqnum)
		if col.DataType() != uint8(types.T_TS) {
			putFillHolder(i, seqnum)
		} else {
			ext := col.Location()
			ioVec.Entries = append(ioVec.Entries, fileservice.IOEntry{
				Offset: int64(ext.Offset()),
				Size: int64(ext.Length()),
				ToCacheData: factory(int64(ext.OriginSize()), ext.Alg()),
			})
		}
		continue
	}
	// need fill vector
	if seqnum > maxSeqnum || blkmeta.ColumnMeta(seqnum).DataType() == 0 {
		putFillHolder(i, seqnum)
		continue

if col.DataType() == uint8(types.T_TS) && i == len(c.cols)-1 {
	idxs = append(idxs, objectio.SEQNUM_COMMITTS)
} else {
	idxs = append(idxs, idx)
}
typs = append(typs, tp)

logutil.Info("committs replace",
	zap.Bool("createdByCN", stats.GetCNCreated()),
	zap.Bool("appendable", stats.GetAppendable()),
	zap.String("createdTS", createTS.String()),
	zap.Int("length", length),
)