[LUCENE-1690] Morelikethis queries are very slow compared to other search types

• Type: Improvement
• Status: Open
• Priority: Minor
• Resolution: Unresolved
• Affects Version/s: 2.4.1
• Component/s: modules/other
• Lucene Fields: New
• Assignee: Unassigned
• Reporter: Richard Marr
• Created: 13/Jun/09 05:36
• Updated: 28/Aug/22 12:02

Description

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.