2010YOUY01 commented on issue #22723:
URL: https://github.com/apache/datafusion/issues/22723#issuecomment-4632466216

   I don't think the error message is the key issue. The problem is that this 
direction enforces an invariant that does not exist today.
   
   More specifically, the bug reported by this issue — internal accounting 
showing 150 KB vs. actual allocation of 770 KB — is arguably a feature rather 
than a bug under the current convention. See:
   
   * 
https://github.com/apache/datafusion/blob/84bc8761ac3a126e41658b6cd0ec6bd8cc34cda8/datafusion/execution/src/memory_pool/mod.rs#L60-L69
   * https://github.com/apache/datafusion/issues/22723#issuecomment-4618433648
   
   I think it is fair to say that this convention may be a bad design, and I am 
+1 on exploring a direction to fix it. However, I do not think we should write 
tests that assume this convention has already been invalidated.
   
   In particular, enabling this `slt` check would effectively assert that 
`MemoryPool` accounting must closely track actual allocator usage. That is 
inconsistent with both the current implementation and the documented 
convention, where the memory pool intentionally accounts for selected 
operator-managed memory rather than every byte actually allocated. So the test 
would not just catch regressions; it would implicitly change the contract by 
assuming a new accounting convention.
   
   If we can agree on that, I am happy to help provide pointers for exploring 
an alternative memory-accounting convention, and eventually enabling this `slt` 
validation once the new convention is defined.


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