On Sun, Sep 23, 2012 at 8:18 PM, Віталій Тимчишин <tiv...@gmail.com> wrote: > If you think about space, use Leveled compaction! This won't only allow you > to fill more space, but also will shrink you data much faster in case of > updates. Size compaction can give you 3x-4x more space used than there are > live data. Consider the following (our simplified) scenario: > 1) The data is updated weekly > 2) Each week a large SSTable is written (say, 300GB) after full update > processing. > 3) In 3 weeks you will have 1.2TB of data in 3 large SSTables. > 4) Only after 4th week they all will be compacted into one 300GB SSTable. > > Leveled compaction've tamed space for us. Note that you should set > sstable_size_in_mb to reasonably high value (it is 512 for us with ~700GB > per node) to prevent creating a lot of small files.
512MB per sstable? Wow, that's freaking huge. From my conversations with various developers 5-10MB seems far more reasonable. I guess it really depends on your usage patterns, but that seems excessive to me- especially as sstables are promoted. -- Aaron Turner http://synfin.net/ Twitter: @synfinatic http://tcpreplay.synfin.net/ - Pcap editing and replay tools for Unix & Windows Those who would give up essential Liberty, to purchase a little temporary Safety, deserve neither Liberty nor Safety. -- Benjamin Franklin "carpe diem quam minimum credula postero"
