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 > >
