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https://issues.apache.org/jira/browse/SLING-12251?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Patrique Legault resolved SLING-12251.
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Resolution: Invalid
> Null Props Cause Incorrect Query Estimation
> --------------------------------------------
>
> Key: SLING-12251
> URL: https://issues.apache.org/jira/browse/SLING-12251
> Project: Sling
> Issue Type: Bug
> Components: Oak
> Reporter: Patrique Legault
> Priority: Major
> Attachments: Non Union Query Plan.json, Non Union With Null
> Check.json, Screenshot 2024-02-13 at 10.17.31 AM.png, Union Query Plan.json,
> cqTagLucene.json
>
>
> Using null props in a query can cause the query engine to incorrectly
> estimate the cost of query plan which can lead to a traversal and slow
> queries to execute.
>
> If you look at the query plan below the number of null props documents is
> quiet high yet the cost for the query is only 19. When we execute the UNION
> query the cost is 38 which is why it is not selected when in reality the
> original cost should be much higher.
>
> After removing the null check the cost estimation is drastically different
> and correctly reflects the number of documents in the index.
>
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