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From Erik Hatcher <>
Subject Re: partial reindex
Date Wed, 05 Oct 2005 12:38:21 GMT
On Oct 5, 2005, at 7:38 AM, Eugeny N Dzhurinsky wrote:
> On Wed, Oct 05, 2005 at 07:03:45AM -0400, Erik Hatcher wrote:
>> On Oct 5, 2005, at 4:01 AM, Eugeny N Dzhurinsky wrote:
>>> Is it possible somehow to change some partial fields in indexed
>>> documents without reindexing all documents?
>> No, not with Lucene 1.4.3.  But the Subversion trunk has a feature
>> that can facilitate this sort of thing by building two indexes, one
>> with the data and one with the security information.  Look at
>> ParallelReader and it's javadocs.
> Ok, thanks, I will review things you mentioned. But could Lucene  
> mix up 2
> indexes in single query?

Using ParallelReader - yes.  Read the javadocs to learn more.

>> However, for data like permissions, ACL's, groups, etc, it may be
>> better to keep the information where it originally resides and have a
>> Filter that accesses the external data.  It would likely be easier
>> and quicker to re-instantiate Filter's than to rebuild a security
>> index and less duplication.
> But what about the case if only 1 result is allowed to be displayed by
> application, but there are thousands of hits, which needs to be  
> filtered for
> ACLs?

Filters may be expensive to create, but once created and cached they  
are rapid.  Each user, for example, may have their own associated  
filter.  Or each group, or something like that.  You'd only need to  
rebuild the filters when permissions changed, but that may be better  
than rebuilding an index.

> As far as I understand, this can be the pain, because Lucene keeps  
> the results
> in memory, correct?

Results?!  As in Hits?  No.   Filters, yes, perhaps.  Architecturally  
that is your decision though.

> So it is better to find solution for pre-filtering rather
> than post-filtering, since last one could be resource-expensive.

I recommend trying it out and seeing if it works for you.

> May be you
> could suggest some another index/search engines?

I'm a little too biased for that :)


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