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From robert engels <>
Subject Re: [jira] Commented: (LUCENE-565) Supporting deleteDocuments in IndexWriter (Code and Performance Results Provided)
Date Mon, 10 Jul 2006 13:30:23 GMT
You keep stating that you never need to close the IndexWriter. I  
don't believe this is the case, and you are possibly misleading  
people as to the extent of your patch.

Don't you need to close (or flush) to get the documents on disk, so  
a  new IndexReader can find them? If not any documents added using  
your IndexWriter are not visible. If I open another IndexReader while  
the IndexWriter is open, I don't not have any deterministic way of  
knowing what should be available.

On Jul 9, 2006, at 11:25 PM, Ning Li wrote:

>> To clarify, higher level (application level) adds and deletes can be
>> managed at a lower level such that index readers and writers aren't
>> continually opened and closed.
> ...
>> The big question is, what kind of efficiencies do you get by putting
>> this functionallity in IndexWriter vs a higher level class that uses
>> IndexWriters and IndexReaders?  Unless there is a clear performance
>> win, I'd prefer leaving IndexWriter simpler.
> I think Lucene wants to excel not only in performance and
> functionality, but also in operability. Almost all the Lucene newbies
> that I know went through this learning curve of realizing you have to
> batch inserts and deletes to achieve good performance. For some of
> them, this cannot be easily done in the application level. This patch
> improves operability for all of them, and it provides performance
> improvement for the later group of people.
> Conceptually, it's a clean modification. IndexWriter (or
> IndexModifier) uses IndexReader to delete, just as IndexWriter already
> uses IndexReader to merge. IndexWriter uses the same write lock it
> acquired in its constructor to add AND delete documents, so ideally,
> you never need to close IndexWriter! I really think it's worth it. :-)
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