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From Erick Erickson <erickerick...@gmail.com>
Subject Re: Document updates work as delete/add under the hood
Date Fri, 10 Jul 2015 16:31:16 GMT
Well, if it's a docValues field you can do update in place at the Lucene level
for certain types of simple values (numerics, strings, but not text types)
see: https://issues.apache.org/jira/browse/LUCENE-5189

In essence the reason it's a delete/re-add is that the
structure of the postings list and the promise that Lucene segments
are write-once makes it fiendishly complex and error-prone.

So yes, it's extra work. But do you have any evidence that your update
rate is such that it's prohibitive?

Best,
Erick

On Fri, Jul 10, 2015 at 2:45 AM, Gimantha Bandara <gimantha@wso2.com> wrote:
> ah.. I misread the thread,I thought you were using two APIs to acheive the
> same done by updateDocument. Yes it is an overhead and harder for user to
> keep track of the fields that he doesn't need to update. Already there is a
> Jira opened for this[1].
>
> [1] https://issues.apache.org/jira/browse/LUCENE-4258
>
> On Fri, Jul 10, 2015 at 1:58 PM, chalitha udara Perera <
> chalithaudara@gmail.com> wrote:
>
>> Hi Gimatha,
>>
>> Yes. It is possible to use IndexWriter updateDocument() to update document.
>> But with that method what happens under the hood is it deletes matching
>> documents and re-index new document. I need to update only a single field.
>> Re-indexing a new document with updated field + other fields seems to be
>> big overhead. My question is, why lucene does that and currently is there a
>> way we can avoid this ?
>>
>> Thanks,
>> Chalitha
>>
>> On Fri, Jul 10, 2015 at 1:46 PM, Gimantha Bandara <gimantha@wso2.com>
>> wrote:
>>
>> > Hi Chalitha,
>> >
>> > You can simply use indexWriter.updateDocument to update the existing
>> index
>> > documents
>> >
>> > On Fri, Jul 10, 2015 at 11:38 AM, chalitha udara Perera <
>> > chalithaudara@gmail.com> wrote:
>> >
>> > > Hi All,
>> > >
>> > > I have a requirement for updating lucene index (add single field for
>> > > existing docs and modify value of another field). These documents
>> contain
>> > > many other fields that do not need any modifications. But as I
>> understand
>> > > luence provides delete/add mechanism for even single field value
>> > updates. I
>> > > would really  appreciate if someone can explain me why lucene use these
>> > > delete/add for updates as it feels like a real bottleneck.
>> > >
>> > > Is there any way to do single fields updates without using delete/add ?
>> > >
>> > > Thanks,
>> > > Chalitha
>> > >
>> > > --
>> > > J.M Chalitha Udara Perera
>> > >
>> > > *Department of Computer Science and Engineering,*
>> > > *University of Moratuwa,*
>> > > *Sri Lanka*
>> > >
>> >
>> >
>> >
>> > --
>> > Gimantha Bandara
>> > Software Engineer
>> > WSO2. Inc : http://wso2.com
>> > Mobile : +94714961919
>> >
>>
>>
>>
>> --
>> J.M Chalitha Udara Perera
>>
>> *Department of Computer Science and Engineering,*
>> *University of Moratuwa,*
>> *Sri Lanka*
>>
>
>
>
> --
> Gimantha Bandara
> Software Engineer
> WSO2. Inc : http://wso2.com
> Mobile : +94714961919

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