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https://issues.apache.org/jira/browse/LUCENE-9857?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17314006#comment-17314006
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Julie Tibshirani commented on LUCENE-9857:
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Hello [~gf2121]! I think that when we cache an IndexOrDocValueQuery, we always
make sure to use the 'index' version. This is because we pass a lead cost of
{{Long.MAX_VALUE}} when building the scorer:
https://github.com/apache/lucene/blob/main/lucene/core/src/java/org/apache/lucene/search/LRUQueryCache.java#L769.
Are you seeing a surprising behavior in tests/ benchmarks that led you to file
the issue? It could be that we're still missing some detail.
> Skip cache building if IndexOrDocValuesQuery choose the dvQuery
> ---------------------------------------------------------------
>
> Key: LUCENE-9857
> URL: https://issues.apache.org/jira/browse/LUCENE-9857
> Project: Lucene - Core
> Issue Type: Improvement
> Components: core/search
> Affects Versions: main (9.0)
> Reporter: Feng Guo
> Priority: Major
> Time Spent: 10m
> Remaining Estimate: 0h
>
> IndexOrDocValuesQuery can automatically use dvQueries when the cost > 8 *l
> eadcost, And the LRUQueryCache skips cache building when cost > 250(By
> default) * leadcost. There is a gap between 8 and 250, which means if the
> factor is just between 8 and 250 (e.g. cost = 10 * leadcost), the
> IndexOrDocValueQuery will choose the dvQueries but LRUQueryCache still build
> cache for it.
> IndexOrDocValuesQuery aims to speed up queries when the leadcost is small,
> but building cache by dvScorers can make it meaningless because it needs to
> scan all the docvalues. This can be rather slow for big segments, so maybe we
> should skip the cache building for IndexOrDocValuesQuery when it chooses
> dvQueries.
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