On Thu, Feb 14, 2019 at 4:39 PM Jeff Jirsa <jji...@gmail.com> wrote: > > Wait, doesn't cleanup just rewrite every SSTable one by one? Why would compaction strategy matter? Do you mean that after cleanup STCS may pick some resulting tables to re-compact them due to the min/max size difference, which would not be the case with LCS? > > > LCS has smaller, non-overlapping files. The upleveling process and non-overlapping part makes it very likely (but not guaranteed) that within a level, only 2 sstables will overlap a losing range. > > Since cleanup only rewrites files if they’re out of range, LCS probably only has 5 (levels) * 2 (lower and upper) * number of ranges sstables that are going to get rewritten, where TWCS / stcs is probably going to rewrite all of them.
Thanks for the explanation! Still with the default number of vnodes, there is probably not much of a difference as even a single additional node will touch a lot of ranges? -- Alex
