reduce log in merge

                auto curr_offset = fsize;

                // append mode, just increment file size

                fsize += op.size();

                {

                    std::ofstream log("/tmp/trace_daemon.log",

                                      std::ios_base::app);

                    log << "[DAEMON] FullMergeV2: append true. curr: "

                        << curr_offset << " add: " << op.size()

                        << " new: " << fsize << " merge_id: " << op.merge_id()

                        << std::endl;

                }

                std::cerr << "[DAEMON] FullMergeV2: append true. curr: "

                          << curr_offset << " add: " << op.size()

                          << " new: " << fsize << " merge_id: " << op.merge_id()

                          << std::endl;

                // save the offset where this append operation should start

                // it is retrieved later in RocksDBBackend::increase_size_impl()

                GKFS_METADATA_MOD->append_offset_reserve_put(op.merge_id(),

                                                             curr_offset);

            } else {

                GKFS_METADATA_MOD->log()->info(

                GKFS_METADATA_MOD->log()->merge(

                        "{}() IncreaseSize: append false. curr: {}, op: {}",

                        __func__, fsize, op.size());

                fsize = ::max(op.size(), fsize);