Bukkit

http://dev.bukkit.org/bukkit-plugins/logblock/

LogBlock integration to use same block change records saves space by not having data doubled. Of course, a config option to toggle this; when enabled, Statistics doesn't log block destructions/creations and gets everything from LogBlock. I imagine having this setting in the database is necessary, for portal.

However, LogBlock's record format doesn't make sense without checking source code, though. To an extent one can understand something by checking for changes for a specific coordinate and comparing the returned data with what's in the database.