A performance evaluation of log-only temporal object database systems

An alternative to in-place updating of data is to eliminate the database completely, and use a log-only approach. The log is written contiguously to the disk, in a no-overwrite way, in large blocks. The log-only approach is particularly interesting for transaction time object database systems (TODB), because keeping previous versions of objects is a feature that comes for free. One of the objections against log-only databases has been that the read cost will be prohibitively high because of loss of clustering. However in our comparison of the performance of log-only and in-place update TODBs, the analysis shows that with the workload we expect to be typical for future TODBs, the log-only approach is highly competitive with the traditional in-place update approach.