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From Otis Gospodnetic <>
Subject Re: Best Practices for indexing in Web application
Date Mon, 01 Mar 2004 12:07:03 GMT

--- Michael Steiger <> wrote:
> Hello Lucene Users,
> I have a web application using Oracle as the database and I want to
> add 
> fulltext query capablities. My idea was to extend the existing
> insert, 
> update and delete methods of my backend classes to add, delete/add
> and 
> delete respectively.
> I'm new to Lucene and after a bit of googling and reading I found a
> few 
> issues which I do not know how to resolve in the moment.
> 1. Concurrency of IndexWriter and IndexReader
> It seems that it is not allowed to open an IndexWriter and an 
> IndexReader at the same time. But if one user is changing records in
> the 
> database (and therefore changing documents in the Lucene index) and 
> another user is querying the index, I would need to open them both.

This problem should be easily solvable through synchronizing on an
object that is used as a shared lock.

> 2. Optimizing the index
> This is maybe related to my first issue.
> I assume that while optimizing the index no queries are allowed. How 
> often should the index be optimized?

Queries are allowed while an index is being optimized.
You can optimize as often as you'd like, but the recommended approach
is to optimize only when you know your index won't change for a while,
or if you are running out of file descriptors.

This is covered in at least one of the Lucene articles (links on the


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