> I think I described the problem wrong :) I don't want to do Java's memory > GC. I want to do cassandra's GC - that is I want to "really" remove deleted > rows from a column family and get my disc space back.
I think that was clear from your post. I don't see a problem with your process. Setting gc grace to 0 and forcing compaction should indeed return you to the smallest possible on-disk size. Did you really not see a *decrease*, or are you just comparing the final size with that of PostgreSQL? Keep in mind that in many cases (especially if not using compression) the Cassandra on-disk format is not as compact as PostgreSQL. For example column names are duplicated in each row, and the row key is duplicated twice (once in index, once in data). -- / Peter Schuller (@scode, http://worldmodscode.wordpress.com)
