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https://issues.apache.org/jira/browse/LUCENE-10509?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Adrien Grand resolved LUCENE-10509.
-----------------------------------
Resolution: Not A Problem
I suspect that this is due to LUCENE-9663, which improved compression of the
terms dictionary. This affected OpenSearch because the cardinality aggregation
performs value lookups on each document. You should open an issue against
OpenSearch to change the way cardinality aggregations run to collect matching
ordinals into a bitset first, and only look up values once the entire segment
has been collected, this should address the performance problem and will likely
make the cardinality aggregation faster than it was before Lucene 8.9.
> Performance degraded after upgrade from 8.8.2 to 8.9.0
> ------------------------------------------------------
>
> Key: LUCENE-10509
> URL: https://issues.apache.org/jira/browse/LUCENE-10509
> Project: Lucene - Core
> Issue Type: Bug
> Affects Versions: 8.8.2
> Reporter: Rajesh T
> Priority: Minor
>
> We are planning to upgrade from elasticsearch 7.7.1 to opensearch 1.1.0 (with
> lucene version 8.9.0). We have noticed that the performance of opensearch
> 1.1.0 is worse than elasticsearch 7.7.1 due to lucene 8.9.0 version. Whereas
> performance of opensearch 1.0.1 (with lucene version 8.8.2) is almost same as
> elasticsearch 7.7.1 version.
> We have tested following scenarios and observed the slowness is caused by
> lucene 8.9.0 version. The performance is degraded by 50% for cardinality
> aggregations.
> Elasticsearch 7.7.1 version (with lucene-core 8.5.1) : Fast
> OpenSearch 1.0.1 version (with lucene-core 8.8.2) : Fast
> OpenSearch 1.1.0 version (with lucene-core 8.9.0) : Slow
> OpenSearch 1.1.0 version (with lucene-core 8.8.2) : Fast
> This is the snippet of openseach code which is running slow with lucene 8.9.0
> {code:java}
> QueryBuilder qb =
> QueryBuilders.boolQuery().mustNot(QueryBuilders.termQuery("__id.keyword",
> randomValue));
> CardinalityAggregationBuilder agg = AggregationBuilders
> .cardinality("somename")
> .field("__id.keyword");
> return client.prepareSearch(index).setQuery(qb).addAggregation(agg);
> {code}
> Please let us know if this is something that can be fixed.
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