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Posted to issues@lucene.apache.org by "Lu Xugang (Jira)" <ji...@apache.org> on 2022/05/24 02:51:00 UTC

[jira] [Updated] (LUCENE-10590) Indexing all zero vectors leads to heat death of the universe

     [ https://issues.apache.org/jira/browse/LUCENE-10590?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Lu Xugang updated LUCENE-10590:
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    Attachment: image.png

> Indexing all zero vectors leads to heat death of the universe
> -------------------------------------------------------------
>
>                 Key: LUCENE-10590
>                 URL: https://issues.apache.org/jira/browse/LUCENE-10590
>             Project: Lucene - Core
>          Issue Type: Bug
>            Reporter: Michael Sokolov
>            Priority: Major
>         Attachments: image.png
>
>
> By accident while testing something else, I ran a luceneutil test indexing 1M 100d vectors where all the vectors were all zeroes. This caused indexing to take a very long time (~40x normal - it did eventually complete) and the search performance was similarly bad.  We should not degrade by orders of magnitude with even the worst data though.
> I'm not entirely sure what the issue is, but perhaps as long as we keep finding hits that are "better" we keep exploring the graph, where better means (score, -docid) >= (lowest score, -docid). If that's right and all docs have the same score, then we probably need to either switch to > (but this could lead to poorer recall in normal cases) or introduce some kind of minimum score threshold?



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