github-actions[bot] commented on code in PR #68258:
URL: https://github.com/apache/doris/pull/68258#discussion_r4056555714
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be/src/exprs/function/math.cpp:
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@@ -643,6 +643,15 @@ class FunctionMathBinary : public IFunction {
auto& a = column_left_ptr->get_data();
auto& c = column_result->get_data();
size_t size = a.size();
+ if constexpr (std::is_same_v<Impl, PowImpl>) {
+ // Dispatch once per block, keeping libm calls out of the
squaring loop.
+ if (column_right_ptr->template get_value<Impl::type>() == 2.0)
{
Review Comment:
[P1] Keep `pow` results independent of column shape and BE version. This
branch is the only shape that uses multiplication; `vector_vector`,
`constant_vector`, and all-constant evaluation still call libm. For `x =
1.1500729535343723e-17`, libm returns `0x1.5fa01b171cd7ap-113` while `x * x`
returns `0x1.5fa01b171cd7bp-113`, so the same argument values become unequal
DOUBLE keys depending on whether the exponent is physically constant. The same
split occurs across old/new BEs during a rolling upgrade and can produce
separate `GROUP BY`/join keys for identical source values. Please preserve one
value semantics across shapes and mixed versions (or avoid the specialization
until that is possible), and add an exact-bit counterexample across the
const-mask matrix; the current values plus `EXPECT_DOUBLE_EQ` do not detect
this.
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