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From "wolfgang hoschek (JIRA)" <j...@apache.org>
Subject [jira] Commented: (LUCENE-550) InstanciatedIndex - faster but memory consuming index
Date Tue, 21 Nov 2006 23:32:04 GMT
    [ http://issues.apache.org/jira/browse/LUCENE-550?page=comments#action_12451817 ] 
            
wolfgang hoschek commented on LUCENE-550:
-----------------------------------------

> All Lucene unit tests have been adapted to work with my alternate index. Everything but
proximity queries pass. 

Sounds like you're almost there :-)

Regarding indexing performance with MemoryIndex: Performance is more than good enough. I've
observed and measured that often the bottleneck is not the MemoryIndex itself, but rather
the Analyzer type (e.g. StandardAnalayzer) or the I/O for the input files or term lower casing
(http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=6265809) or something else entirely.

Regarding query performance with MemoryIndex: Some queries are more efficient than others.
For example, fuzzy queries are much less efficient than wild card queries, which in turn are
much less efficient than simple term queries. Such effects seem partly inherent due too the
nature of the query type, partly a function of the chosen data structure (RAMDirectory, MemoryIndex,
II, ...), and partly a consequence of the overall Lucene API design.

The query mix found in testqueries.txt is more intended for correctness testing than benchmarking.
Therein, certain query types dominate over others, and thus, conclusions about the performance
of individual aspects cannot easily be drawn.

Wolfgang.


> InstanciatedIndex - faster but memory consuming index
> -----------------------------------------------------
>
>                 Key: LUCENE-550
>                 URL: http://issues.apache.org/jira/browse/LUCENE-550
>             Project: Lucene - Java
>          Issue Type: New Feature
>          Components: Store
>    Affects Versions: 1.9
>            Reporter: Karl Wettin
>         Attachments: class_diagram.png, class_diagram.png, instanciated_20060527.tar,
InstanciatedIndexTermEnum.java, lucene.1.9-karl1.jpg, lucene2-karl_20060722.tar.gz, lucene2-karl_20060723.tar.gz
>
>
> After fixing the bugs, it's now 4.5 -> 5 times the speed. This is true for both at
index and query time. Sorry if I got your hopes up too much. There are still things to be
done though. Might not have time to do anything with this until next month, so here is the
code if anyone wants a peek.
> Not good enough for Jira yet, but if someone wants to fool around with it, here it is.
The implementation passes a TermEnum -> TermDocs -> Fields -> TermVector comparation
against the same data in a Directory.
> When it comes to features, offsets don't exists and positions are stored ugly and has
bugs.
> You might notice that norms are float[] and not byte[]. That is me who refactored it
to see if it would do any good. Bit shifting don't take many ticks, so I might just revert
that.
> I belive the code is quite self explaining.
> InstanciatedIndex ii = ..
> ii.new InstanciatedIndexReader();
> ii.addDocument(s).. replace IndexWriter for now.

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