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From "Uwe Schindler (JIRA)" <>
Subject [jira] Commented: (LUCENE-1461) Cached filter for a single term field
Date Tue, 30 Jun 2009 08:04:47 GMT


Uwe Schindler commented on LUCENE-1461:

It seems that the latest patch has no problems anymore. Without deletions or if 0 is not inside
the range it seems to be faster than trie range, with the problem of long first-time searches
(cache loading). But if you e.g. search on this field or use the cache for something other,
it may not be a problem.

The biggest advantage of this is, that you do not need to index the values in a special way,
you can simply use your old Number.toString() formatted fields and do range queries on them.
For term/string ranges it works better than RangeFilter, but the memory usage is much higher
(if you have lots of distinct terms) with StringIndex.

Maybe for the future, there would also be a possibility to implement a TrieRangeQuery for
Strings (the precisionStep would there be the number of chars per precision, so e.g. precStep=2
would be to index for "lucene" the tokens "lu", "luce", "lucene"). The same here like with
TrieRange: a TokenStream that does this would be good.

In my opinion, this class is a good approach for range queries, if you have enough RAM and
warm your searchers correctly, but do not want to change you index structure to use the new
TrieRange. This class is not good for indexes where you will hit only few documents per range,
as the cost of the linear scan for all data types then overweight.

I think I will commit this later, if nobody objects. If you think, that only StringIndex and
not numeric values should be handled by this class (throw away the new code), I tend to rename
this class before release according to LUCENE-1713.

> Cached filter for a single term field
> -------------------------------------
>                 Key: LUCENE-1461
>                 URL:
>             Project: Lucene - Java
>          Issue Type: New Feature
>            Reporter: Tim Sturge
>            Assignee: Uwe Schindler
>             Fix For: 2.9
>         Attachments:, FieldCacheRangeFilter.patch, LUCENE-1461.patch,
LUCENE-1461.patch, LUCENE-1461.patch, LUCENE-1461.patch, LUCENE-1461.patch, LUCENE-1461.patch,
LUCENE-1461.patch, LUCENE-1461a.patch, LUCENE-1461b.patch, LUCENE-1461c.patch,,,,, TestFieldCacheRangeFilter.patch
> 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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