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From Bernhard Messer <>
Subject Re: auto-generate uid?
Date Mon, 22 Nov 2004 21:59:43 GMT
Just to clarify. I have a Field 'uid' those value is an unique integer. 
I  use it as a key to the document stored externally. I don't mean 
Lucene's  internal document number.

> I was wonder if there is a method to query the highest value of a 
> field,  perhaps something like:
>   IndexReader.maxTerm('uid')
what you could do is to write your own IndexWriter class by extending 
the original one found in org.apache.lucene.index.IndexWriter. Than you 
have direct access to lucene's segment counter which could provide you a 
unique id for each document in the index. Those id's would stay sticky 
even if you modify the index after the intial creation process.

is that the hint you need to start ?


>> What would the purpose of an auto-generated UID be?
>> But no, Lucene does not generate UID's for you.  Documents are 
>> numbered  internally by their insertion order.  This number changes, 
>> however, when  documents are deleted in the middle and the index is 
>> optimized.
>>     Erik
>> On Nov 22, 2004, at 1:50 PM, aurora wrote:
>>> Is there a way to auto-generate uid in Lucene? Even it is just a way 
>>> to  query the highest uid and let the application add one to it will 
>>> do.
>>> Thanks.
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