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Posted to issues@lucene.apache.org by "Ignacio Vera (Jira)" <ji...@apache.org> on 2019/09/26 16:01:00 UTC
[jira] [Comment Edited] (LUCENE-8990) IndexOrDocValuesQuery can
take a bad decision for range queries if field has many values per document
[ https://issues.apache.org/jira/browse/LUCENE-8990?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16938748#comment-16938748 ]
Ignacio Vera edited comment on LUCENE-8990 at 9/26/19 4:00 PM:
---------------------------------------------------------------
I was thinking more something like:
{code:java}
double pointsPerDoc = values.size() / values.getDocCount();
values.estimatePointCount(visitor) / pointsPerDoc;{code}
Maybe that can be abstracted out as a new method in PointValues like {{estimateDocCount()}}.
was (Author: ivera):
I was thinking more something like:
{code:java}
double pointsPerDoc = values.size() / values.getDocCount();
values.estimatePointCount(visitor) / pointsPerDoc;{code}
Maybe that can be abstracted out as a new method in the IntersectVisitor like {{estimateDocCount()}}.
> IndexOrDocValuesQuery can take a bad decision for range queries if field has many values per document
> -----------------------------------------------------------------------------------------------------
>
> Key: LUCENE-8990
> URL: https://issues.apache.org/jira/browse/LUCENE-8990
> Project: Lucene - Core
> Issue Type: Bug
> Reporter: Ignacio Vera
> Priority: Major
>
> Heuristics of IndexOrDocValuesQuery are somewhat inconsistent for range queries . The leadCost that is provided is based on number of documents, meanwhile the cost() of a range query is based on the number of points that potentially match the query.
> Therefore it might happen that a BKD tree has millions of points but this points correspond to just a few documents. Therefore we can take the decision of executing the query using docValues and in fact we are almost scanning all the points.
> Maybe the cost() function for range queries need to take into account the average number of points per document in the tree and adjust the value accordingly.
>
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