Hi Adrien,
Thanks for the help, actually we are trying to compress the
actual posting lists. Our main aim here is to save the disk space as much
as possible occupied by the index created. Is only compressing the posting
lists will suffice the problem or we have to explore more options?
Yours,
Vishwas Jain
13CS10053
Computer Science and Engineering
IIT Kharagpur
Contact - +91 9800168231
On Tue, Mar 29, 2016 at 1:41 PM, Adrien Grand <jpou...@gmail.com> wrote:
> BlockTreeTermsWriter.TermsWriter.finish writes a FST that serves as an
> index of the terms dictionary. It will be used at search time when seeking
> terms in the terms dictionary.
>
> Le lun. 28 mars 2016 à 14:02, Vishwas Jain <vjvis...@gmail.com> a écrit :
>
> > Thanks for the reply and information.
> > I have some doubts regarding the implemenation of lucene54
> > codec when writing the posting lists using the lucene50 postinglistwriter
> > while going through the code. What exactly does the finish() method in
> the
> > TermsWriter class of the BlockTreeTermsWriter.java file do? I have come
> to
> > undertstand that the posting lists(document ID, frequency, etc) is mainly
> > is mainly written using WriteBlock method in the ForUtil.java file...
> >
> > Thanks..
> >
> > On Mon, Mar 28, 2016 at 5:31 PM, Vishwas Jain <vjvis...@gmail.com>
> wrote:
> >
> > > Thanks for the reply and information.
> > > I have some doubts regarding the implemenation of
> lucene54
> > > codec when writing the posting lists using the lucene50
> postinglistwriter
> > > while going through the code. What exactly does the finish() method in
> > the
> > > TermsWriter class of the BlockTreeTermsWriter.java file do? I have come
> > to
> > > undertstand that the posting lists(document ID, frequency, etc) is
> mainly
> > > is mainly written using WriteBlock method in the ForUtil.java file...
> > >
> > > Thanks..
> > >
> > >
> > >
> > >
> > > On Mon, Mar 28, 2016 at 4:21 PM, Greg Bowyer <gbow...@fastmail.co.uk>
> > > wrote:
> > >
> > >> The posting list is compressed using a specialised technique aimed at
> > >> pure numbers. Currently the codec uses a variant of Patched Frame of
> > >> Reference coding to perform this compression.
> > >>
> > >> A good survey of such techniques can be found in the good IR books
> > >> (https://mitpress.mit.edu/books/information-retrieval,
> > >>
> > >>
> >
> http://www.amazon.com/Managing-Gigabytes-Compressing-Multimedia-Information/dp/1558605703
> > >> ,
> > >> http://nlp.stanford.edu/IR-book/) as well as this paper
> > >> http://eprints.gla.ac.uk/93572/1/93572.pdf.
> > >>
> > >> Interestingly, there are potentially some wins in finding better
> integer
> > >> codings (and one of my personal projects is aimed at doing exactly
> > >> this), but I doubt LZ4 compressing the posting list would help all
> that
> > >> much.
> > >>
> > >> Hope this helps
> > >>
> > >> On Mon, Mar 28, 2016, at 10:51 AM, Vishwas Jain wrote:
> > >> > Hello ,
> > >> >
> > >> > We are trying to implement better compression techniques
> in
> > >> > lucene54 codec of Apache Lucene. Currently there is no such
> > compression
> > >> > for
> > >> > posting lists in lucene54 codec but LZ4 compression technique is
> used
> > >> for
> > >> > stored fields. Does anyone know why there is no compression
> technique
> > >> for
> > >> > postings lists? and what are the possible compression that would
> > benefit
> > >> > if
> > >> > implemented?
> > >> >
> > >> > Thanks
> > >>
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> > >>
> > >>
> > >
> >
>
