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From Wei Wang <welshw...@gmail.com>
Subject Re: DocValues questions
Date Thu, 04 Apr 2013 18:53:20 GMT
Hi Adrien,

Thanks for the clarification. It is very helpful. Will try Lucene 4.2 and
AtomicReader API.

Wei

On Thu, Apr 4, 2013 at 11:22 AM, Adrien Grand <jpountz@gmail.com> wrote:

> Hi,
>
> On Thu, Apr 4, 2013 at 10:30 AM, Wei Wang <welshwang@gmail.com> wrote:
> > A few quick questions about DocValues:
> >
> > 1. If only small number of documents have a ShortDocValueField defined,
> > should each document in the index has this field filled with some value?
> > The add() function of Document seems not enforce a DocValues field is
> > always added to each document.
>
> Given the name of the fied you are referring to, I assume that you are
> using Lucene 4.0 or 4.1. I would highly recommend to upgrade to Lucene
> 4.2 since the API has been completely refactored (but the disk format
> is compatible) and should hopefully be a little clearer.
>
> You are right that there is nothing that enforces that every document
> has a value : Lucene will give a default value to documents: 0 for
> numeric doc values and an empty byte array for binary doc values.
>
> > 2. Is there any examples to show how DocValues are stored and retrieved?
> It
> > seems JavaDoc only shows how to add it, and no complete examples are out
> > there.
>
> This should be transparent if you use doc values for eg. sorting.
> Otherwise, just call getNumericDocValues(field), getBinaryDocValues or
> getSortedDocValues on an AtomicReader.
>
> I hope this helps.
>
> --
> Adrien
>
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