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From Kumaran Ramasubramanian <kums....@gmail.com>
Subject Re: how do lucene read large index files?
Date Thu, 24 Nov 2016 15:29:59 GMT
Erick, Thanks a lot for sharing an excellent post...

Btw, am using NIOFSDirectory, could you please elaborate on below mentioned
lines? or any further pointers?

NIOFSDirectory or SimpleFSDirectory, we have to pay another price: Our code
> has to do a lot of syscalls to the O/S kernel to copy blocks of data
> between the disk or filesystem cache and our buffers residing in Java heap.
> This needs to be done on every search request, over and over again.




--
Kumaran R



On Wed, Nov 23, 2016 at 9:17 PM, Erick Erickson <erickerickson@gmail.com>
wrote:

> see Uwe's blog:
> http://blog.thetaphi.de/2012/07/use-lucenes-mmapdirectory-on-64bit.html
>
> Short form: files are read into the OS's memory as needed. the whole
> file isn't read at once.
>
> Best,
> Erick
>
> On Wed, Nov 23, 2016 at 12:04 AM, Kumaran Ramasubramanian
> <kums.134@gmail.com> wrote:
> > Hi All,
> >
> > how do lucene read large index files?
> > for example, if one file (for eg: .dat file) is 4GB.
> > lucene read only part of file to RAM? or
> > is it different approach for different lucene file formats?
> >
> >
> > Related Link:
> > How do applications (and OS) handle very big files?
> > http://superuser.com/a/361201
> >
> >
> > --
> > Kumaran R
>
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