(datafusion) 01/01: Fix memory size accounting for grouped `median` and `avg` (#23357)

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github-merge-queue[bot] pushed a commit to branch gh-readonly-queue/main/pr-23357-059be71a50f805a7ed9bc4b08236210ddaa69f43
in repository https://gitbox.apache.org/repos/asf/datafusion.git

commit 73d5d7803ba1bbea757fe6591371655d0d73875b
Author: linfeng <33...@users.noreply.github.com>
AuthorDate: Thu Jul 9 23:01:53 2026 +0800

    Fix memory size accounting for grouped `median` and `avg` (#23357)
    
    ## Which issue does this PR close?
    
    <!--
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    You can link an issue to this PR using the GitHub syntax. For example
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    - Closes #.
    
    ## Rationale for this change
    
    <!--
    Why are you proposing this change? If this is already explained clearly
    in the issue then this section is not needed.
    Explaining clearly why changes are proposed helps reviewers understand
    your changes and offer better suggestions for fixes.
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    `AvgGroupsAccumulator` stores sums in `Vec<T::Native>`, and
    `MedianGroupsAccumulator` stores grouped values in
    `Vec<Vec<T::Native>>`, but their `size()` implementations used
    `size_of::<T>()` when accounting for those allocations.
    
    This underreports memory usage for those grouped aggregate buffers.
    
    ## What changes are included in this PR?
    
    <!--
    There is no need to duplicate the description in the issue here but it
    is sometimes worth providing a summary of the individual changes in this
    PR.
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    - Use `size_of::<T::Native>()` for grouped `avg` sum storage.
    - Use `size_of::<T::Native>()` for grouped `median` value storage.
    
    ## Are these changes tested?
    
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    We typically require tests for all PRs in order to:
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    Existing aggregate tests pass.
    
    ## Are there any user-facing changes?
    
    No. This only affects internal memory accounting.
    
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    ---------
    
    Co-authored-by: Oleks V <co...@users.noreply.github.com>
---
 datafusion/functions-aggregate/src/average.rs | 9 ++++++++-
 datafusion/functions-aggregate/src/median.rs  | 7 ++++---
 2 files changed, 12 insertions(+), 4 deletions(-)

diff --git a/datafusion/functions-aggregate/src/average.rs b/datafusion/functions-aggregate/src/average.rs
index 06c7694634..278a861de2 100644
--- a/datafusion/functions-aggregate/src/average.rs
+++ b/datafusion/functions-aggregate/src/average.rs
@@ -970,6 +970,13 @@ where
     }
 
     fn size(&self) -> usize {
-        self.counts.capacity() * size_of::<u64>() + self.sums.capacity() * size_of::<T>()
+        // Heap buffers
+        self.counts.capacity() * size_of::<u64>()
+        + self.sums.capacity() * size_of::<T::Native>()
+        // Vec struct overhead (ptr, len, cap) for each field
+        + size_of::<Vec<u64>>()
+        + size_of::<Vec<T::Native>>()
+        // Null tracking buffers
+        + self.null_state.size()
     }
 }
diff --git a/datafusion/functions-aggregate/src/median.rs b/datafusion/functions-aggregate/src/median.rs
index 4a0da10f51..9a6ef3e7e5 100644
--- a/datafusion/functions-aggregate/src/median.rs
+++ b/datafusion/functions-aggregate/src/median.rs
@@ -543,10 +543,11 @@ impl<T: ArrowNumericType + Send> GroupsAccumulator for MedianGroupsAccumulator<T
     fn size(&self) -> usize {
         self.group_values
             .iter()
-            .map(|values| values.capacity() * size_of::<T>())
+            .map(|values| values.capacity() * size_of::<T::Native>())
             .sum::<usize>()
-            // account for size of self.grou_values too
-            + self.group_values.capacity() * size_of::<Vec<T>>()
+            // account for size of self.group_values too
+            + self.group_values.capacity() * size_of::<Vec<T::Native>>()
+            + size_of::<Vec<Vec<T::Native>>>()
     }
 }
 


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