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From "Doron Cohen (JIRA)" <j...@apache.org>
Subject [jira] Commented: (LUCENE-584) Decouple Filter from BitSet
Date Mon, 09 Apr 2007 19:35:32 GMT

    [ https://issues.apache.org/jira/browse/LUCENE-584?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12487616
] 

Doron Cohen commented on LUCENE-584:
------------------------------------

> > When you rerun, you may want to use my alg - to compare the two approaches in one
run. 
> This is more dangerous though. 

Agree. I was trying to get rid of this by splitting each round to 3: - gc(), warm(), work()
- when work() and warm() are the same, just that warm()'s stats are disregarded. Still switching
the order of "by match" and "by bits" yield different results. 

Sometimes we would like not to disregard GC - in particular if one approach is creating more
(or more complex) garbage than another approach. 

Perhaps we should look at two measures: best & avg/sum (2nd ignoring first run, for hotspot).



> Decouple Filter from BitSet
> ---------------------------
>
>                 Key: LUCENE-584
>                 URL: https://issues.apache.org/jira/browse/LUCENE-584
>             Project: Lucene - Java
>          Issue Type: Improvement
>          Components: Search
>    Affects Versions: 2.0.1
>            Reporter: Peter Schäfer
>            Priority: Minor
>         Attachments: bench-diff.txt, bench-diff.txt, BitsMatcher.java, Filter-20060628.patch,
HitCollector-20060628.patch, IndexSearcher-20060628.patch, MatchCollector.java, Matcher.java,
Matcher20070226.patch, Scorer-20060628.patch, Searchable-20060628.patch, Searcher-20060628.patch,
Some Matchers.zip, SortedVIntList.java, TestSortedVIntList.java
>
>
> {code}
> package org.apache.lucene.search;
> public abstract class Filter implements java.io.Serializable 
> {
>   public abstract AbstractBitSet bits(IndexReader reader) throws IOException;
> }
> public interface AbstractBitSet 
> {
>   public boolean get(int index);
> }
> {code}
> It would be useful if the method =Filter.bits()= returned an abstract interface, instead
of =java.util.BitSet=.
> Use case: there is a very large index, and, depending on the user's privileges, only
a small portion of the index is actually visible.
> Sparsely populated =java.util.BitSet=s are not efficient and waste lots of memory. It
would be desirable to have an alternative BitSet implementation with smaller memory footprint.
> Though it _is_ possibly to derive classes from =java.util.BitSet=, it was obviously not
designed for that purpose.
> That's why I propose to use an interface instead. The default implementation could still
delegate to =java.util.BitSet=.

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