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From "Bruce Ritchie" <br...@jivesoftware.com>
Subject RE: MultiSegmentQueryFilter enhancement for interactive indexes?
Date Tue, 11 Jul 2006 03:31:55 GMT
Robert,

Can you quantify 'through the roof' a bit? Are the filters that you are
creating that expensive to create or is it the usage of BitSets that are
the real cause of the performance improvement you've seen?


Regards,

Bruce Ritchie
 
-----Original Message-----
From: robert engels [mailto:rengels@ix.netcom.com] 
Sent: Friday, July 07, 2006 9:35 PM
To: java-dev@lucene.apache.org
Subject: Re: MultiSegmentQueryFilter enhancement for interactive
indexes?

I implemented it and it works great. I didn't worry about the deletions
since by the time a filter is used the deleted documents are already
removed by the query. The only problem that arose out of this was for
things like the ConstantScoreQuery (which uses a filter)
- I needed to modify this query to ignore deleted documents.

Now I have incremental cached filters - the query performance is going
through the roof.



On Jul 7, 2006, at 2:47 PM, Chris Hostetter wrote:

>
> I'm no segments/MultiReader expert, but your idea sounds good to me 
> ... it seems like it would certainly work in the "new segments" 
> situation.
>
> One thing i don't see you mention is dealing with deletions ... i'm 
> not sure if deleting documents cause the version number of an 
> IndexReader to change or not (if it does your job is easy) but even if

> it doesn't I'm guessing you could say that if hasDeletions() returns 
> true, you have to assume you need to invalidate your cached bits 
> (worst case scenerio you are invalidating the cache as often as it is 
> now)
>
>
> : Date: Fri, 7 Jul 2006 00:32:54 -0500
> : From: robert engels <rengels@ix.netcom.com>
> : Reply-To: java-dev@lucene.apache.org
> : To: Lucene-Dev <java-dev@lucene.apache.org>
> : Subject: MultiSegmentQueryFilter enhancement for interactive 
> indexes?
> :
> : I thought of a possible enhancement - before I go down the road, I 
> am
> : looking for some input form the community?
> :
> : Currently, the QueryFilter caches the bits base upon the 
> IndexReader.
> :
> : The problem with this is small incremental changes to the index
> : invalidate the cache.
> :
> : What if instead the filter determined that the underlying 
> IndexReader
> : was a MultiReader and then maintained a bitset for each reader,
> : combining them in bits() when requested. The filter could check if
> : any of the underlying readers were the different (removed or added)
> : and then just create a new bitset for that reader. With the new non-
> : bit set filter implementations this could be even more memory
> : efficient since the bitsets would not need to be combined into a
> : single bitset.
> :
> : With the previous work on "reopen" so that segments are reused, this
> : would allow filters to be far more useful in a highly interactive
> : environment.
> :
> : What do you think?
> :
> :
> :
> :
> :
> :
> :  
> ---------------------------------------------------------------------
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> : For additional commands, e-mail: java-dev-help@lucene.apache.org
> :
>
>
>
> -Hoss
>
>
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>


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