ctsk commented on PR #15476: URL: https://github.com/apache/datafusion/pull/15476#issuecomment-2762302514
Before this PR, if someone hand-wired a CollectLeft HashJoin where the left child has more than one output partition, the HashJoin would automatically add a CoalescePartitions exec. This behaviour never triggers for plans that are constructed by datafusion, because the EnforceDistribution pass makes sure that that CoalescePartitions exist. After this PR, if someone hand-wires a CollectLeft HashJoin and does not use the EnforceDistribution pass and provides a left child that has more than 1 output partition, the resulting plan, when executed will return a wrong result (because the hash table will only built on partition 0). Now that I've written it out. I believe it is strictly better to return a plan_err! if one constructs such a plan rather than return a wrong result. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: github-unsubscr...@datafusion.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org --------------------------------------------------------------------- To unsubscribe, e-mail: github-unsubscr...@datafusion.apache.org For additional commands, e-mail: github-h...@datafusion.apache.org
