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From mukkamalla rama kumar <mukkamall...@yahoo.co.in>
Subject Re: reg : document number
Date Mon, 06 Nov 2006 03:10:20 GMT
Thanks for your reply,
   
      Actually what my concern was that,
  I have a file repository, when files are added to this repository i would be updating the
index by the corresponding document.
   
  But during deletion of the file in the file repository i have to delete the document from
the index that i have built. The IndexModifer provides the option
   
  public void deleteDocument(int docNum)

  but this docNum will be varying for the documents, so how can i delete the document when
the files they represent are deleted in my file repository
   
  Thanks in advance for your reply
   
  

Erick Erickson <erickerickson@gmail.com> wrote:
  Do NOT rely on the Lucene document number. It changes periodically. As I
understand it the general algorithm is that each doc gets an ID one greater
than the current max doc ID at INDEX time. However, when you delete
documents and optimize your index, the document IDs change. Simplistically,
say you have docs indexed with IDs 1, 2, 3, 4, 5, remove 2 and reoptimize.
You then have IDs 1, 2, 3, 4 where 2, 3, 4 were 3, 4, 5 respectively.

WARNING: I have no idea whether that's exactly how it works. The point is
that the doc IDs change. I wouldn't count on trying to match any algorithm
that Lucene uses....

But you don't need to anyway. Just assign your own document ID that *you*
can guarantee doesn't change (no relation to the Lucene ID) and store that
wherever you want, then search on that. I believe you'll find that you can
search fast enough on such an ID that you won't notice the time. At any
rate, that's how I'd start out and only get fancier if performance proves
unacceptable.

Best
Erick

On 11/5/06, mukkamalla rama kumar wrote:
>
> Hi,
>
> How is this document number assigned to documents. Can i give my own
> document number.
>
> I would like to get the document number for a particular file that i
> added to an index.
>
>
> ---------------------------------
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