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From "Shah, Vineel" <>
Subject RE: Directory implementation using NIO (moved from Lucene User Li st)
Date Thu, 10 Jul 2003 18:17:41 GMT
On my system, I saw a speedup of 10x when I went from an FSDirectory to a RAMDirectory (loaded
the whole index into RAM.) This was also true in terms of scalability -- .1 searches/sec went
to 8 searches/sec under load (10 threads, no delay between requests.) The index was ~250,000
records in about
200mb on disk.

The search was conducted by a JSP through a Lucene 1.3 dev release (I forget which one) running
under Tomcat. RedHat Linux 6.3 on an Intel machine (I didn't know the mhz, sorry.)


-----Original Message-----
From: Incze Lajos []
Sent: Wednesday, July 09, 2003 9:07 PM
To: Lucene Developers List
Subject: Re: Directory implementation using NIO (moved from Lucene User

> Roughly, a 20% speedup
> > In my case and with my hardware configuration, the index
> > is too big to be loaded in memory with RAMDirectory.
> > On a smaller index or with less RAM available FSDirectory should be
> > faster?

On a very heavily buffering system (like e.g linux) I would not expect
more difference than this 20%. The main difference is not that either is
in memory the other is not in, but the access is throuh inode or page
mapped IO (booth from memory, mostly). That takes the difference.
(At least I think so.)


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