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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 10:04:49 GMT


Paul Elschot commented on LUCENE-1461:

{quote}I tried a short[] array and it is about 20% faster than the int[] array (I'm assuming
this is a memory bandwidth issue.) {quote}
20% is more than I expected. Have a look at LUCENE-1410 for optimal bit packing in a frame
of reference. There are also some performance numbers there for different numbers of frame
bits. (A short[] is equivalent to 16 frame bits.)
This 20% means that it could well be wortwhile to always use such a frame for the docContents

I would not expect that TermMultiFilter has an advantage over a TermFilter, since it does
a linear search even for skipTo(). The only advantage it has it that it does the linear search
from memory where TermFilter does its skipping using the skip info in the index.

Would anyone else have an idea where this could be added, in core or contrib, and what (new)
package name could be used?

> 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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