[jira] [Created] (SLING-12251) Null Props Cause Incorrect Query Estimation

["Patrique Legault (Jira)" <ji...@apache.org>]

Patrique Legault created SLING-12251:
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             Summary: 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
         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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