On 17 September 2011 00:58, mcasandra <mohitanch...@gmail.com> wrote:
> > > >> and updates could be scattered all over > >> before compaction? > > > > No, updates to a given row will be still be in a single sstable. > > Can you please explain little more? You mean that if Level 1 file contains > range from 1-100 all the updates would still go in that file? > No, sstables are never written to. All updates go to a memtable, which is then flushed to a Level0 sstable. Compaction then causes promotion of updates to gradually higher levels. > The link on leveldb says: > > > The compaction picks a file from level L and all overlapping files from > > the next level L+1 > > If all updates go in the same sstables then how do overlapping files get > generated. By overlapping I am assuming it means new or updated value for a > given key exists in multiple files? > Overlapping refers to the range of keys. The key ranges contained within the files in any given level represent a set of disjoint intervals (when level >=1). For Level0, the files may contain overlapping ranges. > Thanks for the explanation > Disclaimer: I haven't read the code, this is just my understanding from reading the docs. Sam Overton Acunu | http://www.acunu.com | @acunu
