Document decimal AVG wrapping arithmetic - #23685
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alamb merged 2 commits intoAug 15, 2026
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## main #23685 +/- ##
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@sakshichitnis27 thank you for your contribution! sorry for taking so long, I lost track of this PR. |
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Thanks @AdamGS and @sakshichitnis27 |
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## Which issue does this PR close? - Closes apache#23665 ## Rationale for this change Decimal AVG intentionally uses wrapping arithmetic with a widened intermediate sum type. The existing direct `add_wrapping` and `sub_wrapping` calls made that invariant difficult to audit. ## What changes are included in this PR? - Added small private helpers documenting the widened/headroom contract. - Updated scalar, grouped, merge, retract, and `AVG(DISTINCT)` decimal paths to use the helpers. - Kept the existing state types, return types, and arithmetic behavior unchanged. ## Are these changes tested? - `cargo fmt --all -- --check` - `cargo test -p datafusion-functions-aggregate avg --lib` - `cargo test -p datafusion-functions-aggregate-common avg_distinct --lib` - `cargo clippy -p datafusion-functions-aggregate-common --all-targets -- -D warnings` ## Are there any user-facing changes? No. Co-authored-by: Adam Gutglick <adamgsal@gmail.com>
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Which issue does this PR close?
Rationale for this change
Decimal AVG intentionally uses wrapping arithmetic with a widened intermediate sum type. The existing direct
add_wrappingandsub_wrappingcalls made that invariant difficult to audit.What changes are included in this PR?
AVG(DISTINCT)decimal paths to use the helpers.Are these changes tested?
cargo fmt --all -- --checkcargo test -p datafusion-functions-aggregate avg --libcargo test -p datafusion-functions-aggregate-common avg_distinct --libcargo clippy -p datafusion-functions-aggregate-common --all-targets -- -D warningsAre there any user-facing changes?
No.