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From "Paul Elschot (JIRA)" <>
Subject [jira] Commented: (LUCENE-1461) Cached filter for a single term field
Date Fri, 21 Nov 2008 21:07:44 GMT


Paul Elschot commented on LUCENE-1461:

{quote}I didn't realize people spent so much time on integer packing.{quote}
Well, it appears that the memory-CPU bus really is getting to be a bottleneck, and you're
not the first one to discover that, see the papers on which LUCENE-1410 is based.
Nevertheless I was surprised by a 20% performance increase when moving from int[] to short[].

{quote}I'll port RangeMultiFilter to run on top of FieldCache.{quote}
That means that bit packing could be confined to the FieldCache lateron, which is good.
At the moment I'm factoring out the exceptions in the 1410 code. The FieldCache may need to
wait for that because it will probably not be using exceptions.
Just think of the extreme case of a field that has only two indexed values, it would be effectively
cached as a bit set.

> Cached filter for a single term field
> -------------------------------------
>                 Key: LUCENE-1461
>                 URL:
>             Project: Lucene - Java
>          Issue Type: New Feature
>            Reporter: Tim Sturge
>         Attachments:,,
> These classes implement inexpensive range filtering over a field containing a single
term. They do this by building an integer array of term numbers (storing the term->number
mapping in a TreeMap) and then implementing a fast integer comparison based DocSetIdIterator.
> This code is currently being used to do age range filtering, but could also be used to
do other date filtering or in any application where there need to be multiple filters based
on the same single term field. I have an untested implementation of single term filtering
and have considered but not yet implemented term set filtering (useful for location based
searches) as well. 
> The code here is fairly rough; it works but lacks javadocs and toString() and hashCode()
methods etc. I'm posting it here to discover if there is other interest in this feature; I
don't mind fixing it up but would hate to go to the effort if it's not going to make it into

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