On Thu, May 19, 2011 at 12:35 PM, Jason Rutherglen <jason.rutherg...@gmail.com> wrote: >> And I do agree there are times when mmap is appropriate, eg if query >> latency is unimportant to you, but it's not a panacea and it comes >> with serious downsides > > Do we have a benchmark of ByteBuffer vs. byte[]'s in RAM?
I don't know of a straight up comparison... > There's also RAM based SSDs whose performance could be comparable with > well, RAM. True, though it's through layers of abstraction designed originally for serving files off of spinning magnets :) > Also, with our heap based field caches, the first sorted > search requires that they be loaded into RAM. Then we don't unload > them until the reader is closed? With MMap the unloading would happen > automatically? True, but really if the app knows it won't need that FC entry for a long time (ie, long enough to make it worth unloading/reloading) then it should really unload it. MMap would still have to write all those pages to disk... DocValues actually makes this a lot cheaper because loading DocValues is much (like ~100 X from Simon's testing) faster than populating FieldCache since FieldCache must do all the uninverting. Mike --------------------------------------------------------------------- To unsubscribe, e-mail: dev-unsubscr...@lucene.apache.org For additional commands, e-mail: dev-h...@lucene.apache.org
