Thanks Justin for the helpful response :-) * Can you define what you would consider "huge" regarding # keys?
<http://www.loomlearning.com/> Jonathan Langevin Systems Administrator Loom Inc. Wilmington, NC: (910) 241-0433 - [email protected] - www.loomlearning.com - Skype: intel352 * On Mon, Jul 4, 2011 at 10:14 AM, Justin Sheehy <[email protected]> wrote: > Hi, Jonathan. > > On Mon, Jul 4, 2011 at 9:42 AM, Jonathan Langevin > <[email protected]> wrote: > > > I've seen users show concern of Bitcask's space usage overhead. How does > that > > compare against LevelDB? > > Bitcask doesn't have much in the way of disk space "overhead" unless > you mean that the space used by deleted or overwritten values is not > reclaimed until after a merge. In that way LevelDB is similar since > space used by deleted and overwritten items is reclaimed as they are > moved into older "levels" of the DB. The behavior here is not > identical, but similar in concept. > > By way of comparison, InnoDB imposes about a 2x space overhead cost on > many common datasets but the overhead is usually fairly static. > > > If using a Level backend, what advantages do we lose of Bitcask? ls > replication & > > availability an issue at all? > > The functionality provided by Riak above the storage engines (such as > replication and system-wide availability) are generally not impacted > by your choice of storage engine. > > There are two main things you would lose today: > > 1 - latency > 2 - stability > > The first of these is fundamental: for many usage patterns Bitcask > will have a latency advantage over LevelDB due to being able to > guarantee that it will never perform more than a single disk seek per > operation. > > The second is just about the relative immaturity of LevelDB: we have > not yet seen LevelDB in production environments for an extended amount > of time as we have with Bitcask. Anyone using it now as a Bitcask > replacement should realize that they are on the leading edge and > taking the usual risks that come with adopting new software. That > said, we expect LevelDB to do well over time as one of the alternative > Riak storage engines. > > The main reason to use LevelDB under Riak would be if your number of > keys is huge and thus the RAM consumption of Bitcask would make it > unsuitable. That is, we expect people to use LevelDB in the same > situations that they might previously have chosen Innostore as their > storage engine. > > -Justin >
_______________________________________________ riak-users mailing list [email protected] http://lists.basho.com/mailman/listinfo/riak-users_lists.basho.com
