2010YOUY01 commented on code in PR #13377:
URL: https://github.com/apache/datafusion/pull/13377#discussion_r1841758359
##########
datafusion/physical-plan/src/spill.rs:
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@@ -109,10 +111,80 @@ pub fn spill_record_batch_by_size(
Ok(())
}
+/// Calculate total used memory of this batch.
+///
+/// This function is used to estimate the physical memory usage of the
`RecordBatch`. The implementation will add up all unique `Buffer`'s memory
+/// size, due to:
+/// - The data pointer inside `Buffer` are memory regions returned by global
memory
+/// allocator, those regions can't have overlap.
+/// - The actual used range of `ArrayRef`s inside `RecordBatch` can have
overlap
+/// or reuse the same `Buffer`. For example: taking a slice from `Array`.
+///
+/// Example:
+/// For a `RecordBatch` with two columns: `col1` and `col2`, two columns are
pointing
+/// to a sub-region of the same buffer.
+///
+/// {xxxxxxxxxxxxxxxxxxx} <--- buffer
+/// ^ ^ ^ ^
+/// | | | |
+/// col1->{ } | |
+/// col2--------->{ }
+///
+/// In the above case, `get_record_batch_memory_size` will return the size of
+/// the buffer, instead of the sum of `col1` and `col2`'s actual memory size.
+///
+/// Note: Current `RecordBatch`.get_array_memory_size()` will double count the
+/// buffer memory size if multiple arrays within the batch are sharing the same
+/// `Buffer`. This method provides temporary fix until the issue is resolved:
+/// <https://github.com/apache/arrow-rs/issues/6439>
+pub fn get_record_batch_memory_size(batch: &RecordBatch) -> usize {
Review Comment:
I think they should all be changed, however after changing them in `TopK`,
some existing test cases might be tricky to fix, and more end-to-end tests
should be added. So I plan to do it incrementally.
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