Weiming Wu created LUCENE-10624:
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Summary: 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: 9.2, 9.1, 9.0
Reporter: Weiming Wu
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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