Are you using near-real-time readers? (IndexReader.open(IndexWriter))
Mike McCandless http://blog.mikemccandless.com On Sun, Feb 5, 2012 at 9:03 AM, Cheng <zhoucheng2...@gmail.com> wrote: > Hi Uwe, > > My challenge is that I need to update/modify the indexes frequently while > providing the search capability. I was trying to use FSDirectory, but found > out that the reading and writing from/to FSDirectory is unbearably slow. So > I now am trying the RAMDirectory, which is fast. > > I don't know of MMapDirectory, and wonder if it is as fast as RAMDirectory. > > > On Sun, Feb 5, 2012 at 4:14 PM, Uwe Schindler <u...@thetaphi.de> wrote: > >> Hi Cheng, >> >> It seems that you use a RAMDirectory for *caching*, otherwise it makes no >> sense to write changes back. In recent Lucene versions, this is not a good >> idea, especially for large indexes (RAMDirectory eats your heap space, >> allocates millions of small byte[] arrays,...). If you need something like >> a >> caching Directory and you are working on a 64bit platform, you can use >> MMapDirectory (where the operating system kernel manages the read/write >> between disk an memory). MMapDirectory is returned by default for >> FSDirectory.open() on most 64 bit platforms. The good thing: the "caching" >> space is outside your JVM heap, so does not slowdown the garbage collector. >> So be sure to *not* allocate too much heap space (-Xmx) to your search app, >> only the minimum needed to execute it and leave the rest of your RAM >> available for the OS kernel to manage FS cache. >> >> Uwe >> >> ----- >> Uwe Schindler >> H.-H.-Meier-Allee 63, D-28213 Bremen >> http://www.thetaphi.de >> eMail: u...@thetaphi.de >> >> >> > -----Original Message----- >> > From: Cheng [mailto:zhoucheng2...@gmail.com] >> > Sent: Sunday, February 05, 2012 7:56 AM >> > To: java-user@lucene.apache.org >> > Subject: Configure writer to write to FSDirectory? >> > >> > Hi, >> > >> > I build an RAMDirectory on a FSDirectory, and would like the writer >> associated >> > with the RAMDirectory to periodically write to hard drive. >> > >> > Is this achievable? >> > >> > Thanks. >> >> >> --------------------------------------------------------------------- >> To unsubscribe, e-mail: java-user-unsubscr...@lucene.apache.org >> For additional commands, e-mail: java-user-h...@lucene.apache.org >> >> --------------------------------------------------------------------- To unsubscribe, e-mail: java-user-unsubscr...@lucene.apache.org For additional commands, e-mail: java-user-h...@lucene.apache.org
