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Posted to github@arrow.apache.org by "mingmwang (via GitHub)" <gi...@apache.org> on 2023/04/18 15:08:31 UTC

[GitHub] [arrow-datafusion] mingmwang commented on pull request #5907: optimize non-correlated where exists subquery rewrite to scalar subquery

mingmwang commented on PR #5907:
URL: https://github.com/apache/arrow-datafusion/pull/5907#issuecomment-1513313446

   I will take a look. Usually, for un-correlated scalar subqueries, it will be kept as the subquery but need to do count check.
   
   WHERE  EXISTS (SELECT b FROM t2 where a>1 )
   
   rewrite to 
   
   WHERE  EXISTS (SELECT b FROM t2 where a>1 limit 2)
   
   We need to add a physical SubQueryExec.


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