> Reading in the documentation (specially on the tuning section) is clear the > the number of Column Families affects the performance, in particular the > amount of memory assigned to the heap. > My question is: What's the hard limit on the number of CFs? > Does anybody implemented an application with large number of CFs? if so, > whats that number?
There's no meaningful hard limit as such that I am aware of, but the idea is that you have few of them (meaning usually below 10 or so, maybe more sometimes, but not hundreds or thousands). The overhead associated is indirect in the sense that for a fixed heap size, you'd need lower memtable flush thresholds per cf, leading to smaller sstablers being flushed and thus leading to more compaction. If you have so many memtables that you are worried about a hard limit, you probably have too many of them already for reasons other than any hard limits :) -- / Peter Schuller
