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Posted to dev@lucene.apache.org by "Carl Austin (JIRA)" <ji...@apache.org> on 2009/07/20 16:45:14 UTC
[jira] Commented: (LUCENE-1690) Morelikethis queries are very slow
compared to other search types
[ https://issues.apache.org/jira/browse/LUCENE-1690?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12733234#action_12733234 ]
Carl Austin commented on LUCENE-1690:
-------------------------------------
The cache used for this is a HashMap and this is unbounded. Perhaps this should be an LRU cache with a settable maximum number of entries to stop it growing forever if you do a lot of like this queries on large indexes with many unique terms.
Otherwise nice addition, has sped up my more like this queries a bit.
> Morelikethis queries are very slow compared to other search types
> -----------------------------------------------------------------
>
> Key: LUCENE-1690
> URL: https://issues.apache.org/jira/browse/LUCENE-1690
> Project: Lucene - Java
> Issue Type: Improvement
> Components: contrib/*
> Affects Versions: 2.4.1
> Reporter: Richard Marr
> Priority: Minor
> Attachments: LUCENE-1690.patch
>
> Original Estimate: 2h
> Remaining Estimate: 2h
>
> The MoreLikeThis object performs term frequency lookups for every query. From my testing that's what seems to take up the majority of time for MoreLikeThis searches.
> For some (I'd venture many) applications it's not necessary for term statistics to be looked up every time. A fairly naive opt-in caching mechanism tied to the life of the MoreLikeThis object would allow applications to cache term statistics for the duration that suits them.
> I've got this working in my test code. I'll put together a patch file when I get a minute. From my testing this can improve performance by a factor of around 10.
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