Ádám Szita created HIVE-26137:
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             Summary: Optimized transfer of Iceberg residual expressions from 
AM to execution
                 Key: HIVE-26137
                 URL: https://issues.apache.org/jira/browse/HIVE-26137
             Project: Hive
          Issue Type: Improvement
            Reporter: Ádám Szita


HIVE-25967 introduced a hack to prevent Iceberg filter expressions to be 
serialized into splits. This temporary fix was to avoid OOM problems on Tez AM 
side, but at the same time prevented predicate pushdowns to work on the 
execution side too.

This ticket intends to incorporate the long term solution. It turns out that 
the file scan tasks created by Iceberg actually don't contain a "residual" 
expressions, but rather a complete/original one. It becomes residual only when 
it is evaluated against the tasks' partition value, which only happens on the 
execution site. This means that the original filter is the same expression for 
all splits in Tez AM, so we can transfer it via job conf instead.



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