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https://issues.apache.org/jira/browse/LUCENE-10624?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Weiming Wu updated LUCENE-10624:
--------------------------------
    Attachment: candidate_sparseTaxis_searchsparse-sorted.0.log

> Binary Search for Sparse IndexedDISI advanceWithinBlock & 
> advanceExactWithinBlock
> ---------------------------------------------------------------------------------
>
>                 Key: LUCENE-10624
>                 URL: https://issues.apache.org/jira/browse/LUCENE-10624
>             Project: Lucene - Core
>          Issue Type: Improvement
>          Components: core/codecs
>    Affects Versions: 9.0, 9.1, 9.2
>            Reporter: Weiming Wu
>            Priority: Major
>         Attachments: baseline_sparseTaxis_searchsparse-sorted.0.log, 
> candidate_sparseTaxis_searchsparse-sorted.0.log
>
>          Time Spent: 10m
>  Remaining Estimate: 0h
>
> h3. Problem Statement
> We noticed DocValue read performance regression with the iterative API when 
> upgrading from Lucene 5 to Lucene 9. Our latency is increased by 50%. The 
> degradation is similar to what's described in 
> https://issues.apache.org/jira/browse/SOLR-9599 
> By analyzing profiling data, we found method "advanceWithinBlock" and 
> "advanceExactWithinBlock" for Sparse IndexedDISI is slow in Lucene 9 due to 
> their O(N) doc lookup algorithm. 
> h3. Changes
> Used binary search algorithm to replace current O(N) lookup algorithm in 
> Sparse IndexedDISI "advanceWithinBlock" and "advanceExactWithinBlock" because 
> docs are in ascending order.
> h3. Test
> {code:java}
> ./gradlew tidy
> ./gradlew check {code}
>  



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